Internal wiring of BJ40/BJ42/HJ42 glow relay (Manual glow)

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Internal wiring of BJ40/BJ42/HJ47 glow relay (Manual glow)

Hey. Let's have a "free-for-all" on the subject of the glow/start wiring that was fitted to diesel cruisers produced from around 1977 to 1983 that are "manual glow" (as opposed to "superglow") and are "with EDIC". The most common models affected here are the BJ40, BJ41, BJ42, and the HJ47. (Perhaps the HJ45 too - but I never hear much about those cruisers on the 2 forums I frequent.)

By "free-for- all", I mean a "no-holds-barred" discussion where anyone can say how they think the glow/start system on these cruisers was REALLY wired by the factory and no-one will get offended. - In other words - I'm after what you think the "as-built" wiring really was.

I'm starting this separate thread because I note the discussion occuring in GregFrench's current thread. But I'm reluctant to enter that one because I don't want to divert its course. And the last time Greg sort help, we ended up discussing too many sidetrack issues (totally my fault - I know) that were unrelated to his vehicle or to his particular problem. And my "staying out" allows a fresh approach to be taken there which may well be successful. (I'm thinking of the previous thread's failure to solve Greg's "glow system issues".)

But at the same time, I see "the as-built status of our glow/start wiring" (including the internal wiring of the glow relay) as an important issue to thrash out (and if possible to gain consensus on).

Anyway here is my glow plug relay (lefthand one):

relayglow_start.jpg

And here is the latest diagram (based on a 12V 4-cylinder diesel) that I've modified to what I believe best represents the "as built status" of our glow/start systems. As you can see, it includes the internal wiring of components so you can actually "read" what happens:

WiringStart&Glow.jpg

I can easily "read" how my glow/start system works from this diagram and there are no contradictions (that I'm aware of) between what I read here and how my truck behaves in reality! Now this is something I've found I can't say for any FSM diagram that I've yet come across. (But I won't take offence at anyone's efforts to support an alternative wiring diagram, to suggest changes to mine, or even to trash mine completely.)
relayglow_start.jpg
WiringStart&Glow.jpg
 
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Now I doubt these images will come up well but they show what the FSM diagrams are like:

BJ40BJ43HJ471981.jpg

There's is no "internal information" shown for the "glow plug relay" above which means that you can't "read" how the glow/start system works from this diagram.

Aug1980ChassisFSM.jpg

Oops bit small to read. But if you could, the above diagram shows some internal wiring for the "glow plug relay". However when I try "reading" this diagram I find it has "errors" that suggest whenever I glow my plugs:
  • my starter will start cranking simultaneously, and
  • my glow controller (labelled as "glow plug indicator light" here) gets shorted-out/bypassed (to prevent it from glowing) by the set of contacts that are connected to the "S" terminal.
(Note: - There has been considerable discussion in this forum in recent times over whether or not the "S" terminal on OUR relays is REALLY connected to anything inside the relay enclosure.)

I have yet another wiring diagram similar to this one but showing a separate operating coil for the contacts connected to "S" terminal. However attempts to "read it" show the same operating faults. (I tried copying it here but it comes up far too small to read and I can't seem to find a way to overcome that problem at present.)

BengineFSM.jpg

This one above comes from the "1977 B & 2B Engine Repair Manual" and shows a different internal wiring set-up for my glow relay. And this time, putting my key in "start" is apparently meant to bypass my "glow controller" and in doing so, applies an extra "boost voltage" to my plugs.

PS. This last FSM diagram shows an "overinjection magnet" so perhaps "without EDIC" cruisers got this particular wiring? Then again, perhaps it was just a design-engineer's dream that NEVER came to fruition but somehow ended up in the FSM.





So post away (and let's start a discussion) if.............
  • you think something in my diagram in Post #1 is not correct (based on your experience, findings, or whatever)
  • perhaps you just want me to explain why I may have drawn certain conclusions that you think are "dubious".
  • you have ANY another wiring diagrams at all that show the start/glow wiring in these cruisers for us to look at
  • you have your own views on whether you think the "S" terminal is or isn't connected to anything internally
  • you have anything else to say that is in any way connected with this
BJ40BJ43HJ471981.jpg
BengineFSM.jpg
Aug1980ChassisFSM.jpg
 
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I have an FSM dated 1977 with a wiring diagram labelled LAND CRUISER (BJ40,43) ELECTRICAL WIRING DIAGRAM (Except U.S.A. & CANADA) which shows 5 terminals on the glow plug relay - B from the (24V) battery, ST from the sart position of the ignition switch, G from the glow position of the ignition switch, S which is connected to the B contacter in the relay, another labelled G which is contacted by another contacter in the relay, probably energized by the first G terminal. This one is connected to the to the S terminal outside the relay box. This diagram also shows the affected vehicles to have both an overinjection magnet AND an EDIC system. It also shows 6 glow plugs.

I should point out that my '79 BJ40 came stock from the factory with the manual switch mounted in the dash as well as the glow position on the ignition switch.

My other FSM is from Aug 1980, it looks like the same one you have (diagram 2, post 2)
 
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Thanks for taking this out of my thread. I have a question about your diagram compared to your picture. The picture of the relay shows "G-B-S" connections in that order. Your first diagram (the only one I can read) doesn't have that labeled anywhere. It has "g- ST-B" on one side, and "G-E-S" on the other. Sorry if this is a dumb observation...I am just trying to figure out how it works so I can possibly solve my problem.
 
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Thanks for taking this out of my thread. .....

Well. Our glow systems seem to cause a few headaches from time to time and it seems sensible to me treat this topic on its own and try to thrash it out Greg. (But I risk treading-on-toes no matter what I do really. Even if I were to do nothing!)

.....I have a question about your diagram compared to your picture. The picture of the relay shows "G-B-S" connections in that order. Your first diagram (the only one I can read) doesn't have that labeled anywhere. It has "g- ST-B" on one side, and "G-E-S" on the other. Sorry if this is a dumb observation...I am just trying to figure out how it works so I can possibly solve my problem.

Not dumb at all.

That wiring diagram is drawn up with the aim of being easy to read. So the placement of the terminals there can be (and IS in this case) "different from reality". (Toyota do the same thing with their wiring schematics.)

Here is the diagram with those G, B and S terminals highlighted in red:

Aresp2.jpg

And here is a photo I took just now of the bottom of my glow plug relay with those same terminals labelled in red.

Aresp1.jpg

Incidentally, the other 3 wires connected to the glow plug relay travel there via that connector (where I have labelled the colour-codes on two of the wires).

BW: Black with a white line
WG: White with a green line
And the third wire (unlabelled) is WB (white with black line). And I suspect this last wire is the one being used as the earth (shown in the wiring diagram)

Note that these colour codes are on my "vehicle wiring harness" and those on the other side of the connector (on the "actual relay pigtail" don't fully agree.

:cheers:
Aresp1.jpg
Aresp2.jpg
 
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I have an FSM dated 1977 with a wiring diagram labelled LAND CRUISER (BJ40,43) ELECTRICAL WIRING DIAGRAM (Except U.S.A. & CANADA) which shows 5 terminals on the glow plug relay - B from the (24V) battery, ST from the sart position of the ignition switch, G from the glow position of the ignition switch, S which is connected to the B contacter in the relay, another labelled G which is contacted by another contacter in the relay, probably energized by the first G terminal. This one is connected to the to the S terminal outside the relay box. This diagram also shows the affected vehicles to have both an overinjection magnet AND an EDIC system. It also shows 6 glow plugs.

......

My other FSM is from Aug 1980, it looks like the same one you have (diagram 2, post 2)

Thanks.

Any chance of posting that 1977 diagram? (But I can understand if you can't because I still can't size one of mine well enough for it to come up on the screen in readable form.)

From your description (5 terminals instead of 6) it sounds like the coil's earth connection is missing (compared to my diagrams).

I should point out that my '79 BJ40 came stock from the factory with the manual switch mounted in the dash as well as the glow position on the ignition switch.

Yeah. I've heard this said before. Do you know what market it was sold to? Was it "Japanese domestic market" perhaps?

Australian (& NZ) market never got that.
 
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Thanks Tom this is a good idea.. and you're a good mediator for hotheads like me :D. Sorry for polluting your thread other Greg. Anyway, regarding the mystery relay. No matter what you believe about this creature, I think we can all agree that Toyota has left us a real mess - I can't determine which of the many extant wiring diagrams is authoritative, if any.

The EPC says for BJ4* cruisers:

28610 RELAY ASSY, GLOW PLUG
28610‑46030 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑46031 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑46040 B, 3B..BJ40, 42, 43, 45, 46..GEN, EUR; 24V 1
28610‑46041 B, 3B..BJ40, 42, 43, 45, 46..GEN, EUR; 24V 1
28610‑57070 B, 3B..BJ4*..GEN, ARL; 12V, SUB 1
28610‑57070 B, 3B..BJ4*..GEN; 12V, SUB 1
28610‑57080 B, 3B..BJ40, 42, 43, 45, 46..GEN; 24V, SUB 1
28610‑57080 B, 3B..BJ40, 42, 43..GEN; 24V 1

This is for GEN country vehicles, which means Canadian trucks are another bag of chips entirely, but lets ignore that for now. I checked multiple years (1977 BJ40s and 1982 BJ42s, for example) and all BJ4*'s show the same glow relay listings as above.

For HJ47s (using 1982 as an example) the listing is:

28610 RELAY ASSY, GLOW PLUG
28610‑46030 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑46031 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑68010 2H..HJ47; 12V, SUB 1
28610‑68010 2H..HJ47..GEN; 12V, SUB 1

Frankly, I don't know what to make of the "Substitution" part numbers so in order to keep my head from exploding, lets ignore them and focus on the primary part numbers. It appears then, that all GEN and Aus. cruisers with B, 3B and 2H engines use the 28610-46030 or 28610-46031 relays. The differences between the two part numbers may be crucial to our efforts.

As photographed above, Tom's BJ40 uses a 28610-46030 while my BJ42 uses a 28610-46031 relay. Here are some photos inside the 46031 relay:

attachment.php


Note in this photo that the S terminal is the leftmost connection. Although I don't have a picture that shows it well, note that the S terminal is riveted to the fiber board without any electric connections. There are also no hidden wires or multi-layer board features, the S terminal is truly unconnected.

attachment.php

attachment.php


I have visually and electrically traced the connections of my relay shown above and internally the schematic is (apologies for my poor drawing):

attachment.php


Note that the diodes present are often drawn in FSMs drawings as differentiating the relay function depending on whether "glow" or "start" is selected on the ignition switch. However as I've draw above, and as connected in the 46031 relay, the diodes act only as clamping diodes, protecting the rest of the system from the high voltage pulse all relays produced as the magnetic field inside them decays. There are, in fact, two separate windings on the same magnet core.

Now, the $64,000 question has always been - does this agree with any of the FSM drawings? I'll exclude drawings that don't show internal relay connections, as I believe the external wiring is shown identically in all the drawings. Here are the diagrams that I know of, and my thoughts:

This one is from an HJ47 FSM, and is probably intended to be applicable to all HJ's:
attachment.php


The problem shown above is that the lower contact is shown normally-closed which would have the glow system engaged all the time. This is surely just a typo, so evaluating the rest of the diagram we can see its electrically identical to that which I found inside my own relay, except for the mysterious S terminal. The diodes are shown in clamping configuration, like mine, and two electrical coils on the same core, again just like mine. However the S terminal, as drawn, is a high current connection to the glowplugs and would need a large contact-type connection in the relay - there is no way for something like that to "hide": indeed it is absent in the relay I opened.

Most curiously, however, is that even if we correct the typo for ourselves, you can see that contacts are connection both the S and G terminals to the battery voltage. If you look just beyond the relay, however, you'll notice that this will result in 12V being present on both sides of the glow controller - since current only flows when a voltage differential is present, we can conclude that the glow controller (or glow lamp) would never light up is wired as shown. This relay is physically impossible.

This diagram is for a 1979 North-American BJ4* which uses a DIFFERENT RELAY:
28610 RELAY ASSY, GLOW PLUG
28610‑46040 B..BJ40 1
[EDIT: in fact, this part number is the same as listed above for all 24V GEN countries cruisers. I haven't verified the inside of a 24V relay]
attachment.php


You can see this is more or less identical to the HJ47 diagram, however the typo with the normally closed contact has been corrected while the electrical logic error remains. However you can also see that this system is fitted with a momentary glow switch, outside of the ignition switch (right side), as North american trucks were. If we assume, for a moment, that this 46040 relay had, in fact, two electrically separate relays inside it, one for switching the G terminal when using the glow switches, and one for switching the S terminal when using the starter, then in fact it is electrically consistent. The result would be that using the momentary switch would activate the glow system through the glow controller while when using the starter that glow controller would be bypassed, giving the plugs a slightly (1-2V) higher voltage while starting. This makes some sense to me.

However, unfortunately, this doesn't help us, because the relay shown is a different part number than the one in question.

This diagram is from a 1981 BJ42 (unknown country spec), and is probably the strangest of the bunch:
attachment.php


[EDITTED to correct diode logic errors:]
This time the magnet is shown with only a single coil and the diode is no longer in clamping configuration. However, as the diagram is drawn, the diode has no function and allows a current path from the glow switch to the starter relay, meaning any time you use the glow switch, the starter would crank!! That is simply on top of the usual electrical error, whereby the S terminal is shown wired such as to disable the proper function of the glow controller. This diagram is... mistaken. :D

Ultimately, our conclusions are limited.
  • If you have a [edit] 24V or [end edit] Canadian BJ4*, your unqiue relay may make actual use of the S terminal. The drawing in the FSM, with this interpretation, *is* electrically sound, until someone opens a relay and finds something interesting we won't know for sure.
  • If you've got a GEN countries truck with a 46031 relay, then the S terminal does nothing and the internal construction of the relay is not supported by any of the FSM drawings.
  • If you've got a GEN countries truck with a 46030 relay, your S terminal *might* be connected somehow, however the way its drawn in the FSM is still not electrically possible. - my money is on it being disconnected also.
 
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...
The EPC says for BJ4* cruisers:

28610 RELAY ASSY, GLOW PLUG
28610‑46030 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑46031 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑46040 B, 3B..BJ40, 42, 43, 45, 46..GEN, EUR; 24V 1
28610‑46041 B, 3B..BJ40, 42, 43, 45, 46..GEN, EUR; 24V 1
28610‑57070 B, 3B..BJ4*..GEN, ARL; 12V, SUB 1
28610‑57070 B, 3B..BJ4*..GEN; 12V, SUB 1
28610‑57080 B, 3B..BJ40, 42, 43, 45, 46..GEN; 24V, SUB 1
28610‑57080 B, 3B..BJ40, 42, 43..GEN; 24V 1

This is for GEN country vehicles, which means Canadian trucks are another bag of chips entirely, but lets ignore that for now. I checked multiple years (1977 BJ40s and 1982 BJ42s, for example) and all BJ4*'s show the same glow relay listings as above.

For HJ47s (using 1982 as an example) the listing is:

28610 RELAY ASSY, GLOW PLUG
28610‑46030 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑46031 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑68010 2H..HJ47; 12V, SUB 1
28610‑68010 2H..HJ47..GEN; 12V, SUB 1

Frankly, I don't know what to make of the "Substitution" part numbers so in order to keep my head from exploding, lets ignore them and focus on the primary part numbers. It appears then, that all GEN and Aus. cruisers with B, 3B and 2H engines use the 28610-46030 or 28610-46031 relays. The differences between the two part numbers may be crucial to our efforts.

Wow. Thanks Amaurer. As usual you go to great efforts to help us gain more knowledge/understanding.

I never thought of matching the different glow plug relay part numbers with the different wiring diagrams.

(I must check back to see which relay HJ47/Chris opened up.)

....... Here are some photos inside the 46031 relay:

attachment.php


Note in this photo that the S terminal is the leftmost connection. Although I don't have a picture that shows it well, note that the S terminal is riveted to the fiber board without any electric connections. There are also no hidden wires or multi-layer board features, the S terminal is truly unconnected.

Yes. I wasn't convinced when I saw only your S terminal unconnected, but I was when I saw "Henry James the 47th" find the same result with his.

But of course S terminal is not completely useless. I've found it's position to be convenient for taking test readings (eg. of the voltage-drop across my glow controller). So perhaps Toyota wanted it left there for that purpose alone?

....I have visually and electrically traced the connections of my relay shown above and internally the schematic is (apologies for my poor drawing):

attachment.php


Note that the diodes present are often drawn in FSMs drawings as differentiating the relay function depending on whether "glow" or "start" is selected on the ignition switch. However as I've draw above, and as connected in the 46031 relay, the diodes act only as clamping diodes, protecting the rest of the system from the high voltage pulse all relays produced as the magnetic field inside them decays. There are, in fact, two separate windings on the same magnet core.

And this helped me immensely in constructing my diagram that I placed in post #1. (Especially the bit about "2 windings on the same core".)

I believe my wiring is exactly the same as your sketch except I have left out the "clamping diodes" because they are not necessary for "reading" my diagram. In fact, leaving them in would have made it HARDER for people like me (who know little about "clamping diodes") to read it.

....

This diagram is for a 1979 North-American BJ4* which uses a DIFFERENT RELAY:
28610 RELAY ASSY, GLOW PLUG
28610‑46040 B..BJ40 1
attachment.php


You can see this is more or less identical to the HJ47 diagram, however the typo with the normally closed contact has been corrected while the electrical logic error remains. However you can also see that this system is fitted with a momentary glow switch, outside of the ignition switch (right side), as North american trucks were. ........

Aha.... Well that answers the question I asked of KOOTENAY KRUZER. So it is the Canadian trucks that got the factory "momentary switch".

..If we assume, for a moment, that this 46040 relay had, in fact, two electrically separate relays inside it, one for switching the G terminal when using the glow switches, and one for switching the S terminal when using the starter, then in fact it is electrically consistent. The result would be that using the momentary switch would activate the glow system through the glow controller while when using the starter that glow controller would be bypassed, giving the plugs a slightly (1-2V) higher voltage while starting. This makes some sense to me.

However, unfortunately, this doesn't help us, because the relay shown is a different part number than the one in question.

Unless someone with a Canadian cruiser can tell us that their cruiser actually works this way in practice - I think I'll remain skeptical that this diagram represents any "as-built" wiring Drew.


....This diagram is from a 1981 BJ42 (unknown country spec), and is probably the strangest of the bunch:
attachment.php


This time the magnet is shown with only a single coil and the diodes are no longer in clamping configuration - instead they are protecting the "start" function from being triggered by the relay. One again, electrically, the S terminal is shown wiring such as to disable the proper function of the glow controller.

I agree that the internal glow relay wiring here is nonsense. But perhaps you can school me about the diode symbol there Drew?

I thought such a symbol allowed current flow in the direction shown by the arrowhead within the symbol, but disallowed current flow in the opposite direction?


.....Ultimately, our conclusions are limited.
  • If you have a Canadian BJ4*, your unqiue relay appears to make actual use of the S terminal. There is no reason to doubt the FSM, which is electrically sound, until someone opens a relay and finds something interesting.
Geeeez Drew. You're siding with HJ47 (Chris). I now reckon (in the light of what you and HJ found inside your relay enclosures) that ANY FSM drawing is talking cr#p with regards to the S terminal being connected internally to anything on ANY cruiser. (And I eagerly await to be proven wrong :D) edit later - And later posts within this thread do seem to prove that I am wrong here! They suggest 24V cruisers DO have internal wiring connected to their S terminals!

...
  • If you've got a GEN countries truck with a 46031 relay, then the S terminal does nothing and the internal construction of the relay is not supported by any of the FSM drawings.
  • If you've got a GEN countries truck with a 46030 relay, your S terminal *might* be connected somehow, however the way its drawn in the FSM is still not electrically possible.

You're tempting me to take my 46030 relay apart but I'm not buckling!!!...................................................Yet.


:cheers:
 
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I agree that the internal glow relay wiring here is nonsense. But perhaps you can school me about the diode symbol there Drew?

I thought such a symbol allowed current flow in the direction shown by the arrowhead within the symbol, but disallowed current flow in the opposite direction?

Yep, you've got it right. Hmm, looking at the diagram again (and I think this may be your point), as the diagram is drawn it appears that any time the glow relay is switched, the starter is going to crank... lol, just one more typo, among many! I will edit my prior post.

Geeeez Drew. You're siding with HJ47 (Chris). I now reckon (in the light of what you and HJ found inside your relay enclosures) that ANY FSM drawing is talking cr#p with regards to the S terminal being connected internally to anything on ANY cruiser. (And I eagerly await to be proven wrong :D)

I don't really believe it, honestly, but I'm being generous because I haven't truly verified the internals of every part number relay, so I don't want to bang the drum too hard and come up looking like an a******. You know what I noticed though?? the "different part number" for the Canadian trucks is the SAME part number as GEN BJ4*s which are 24V. So it seems this "different" relay isn't so much a special version for the CDN market with the momentary glow switch, but rather may just be the 24V variant of the same relay!:

28610 RELAY ASSY, GLOW PLUG
28610‑46030 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑46031 B, 3B, 2H..BJ4*, HJ47..GEN, ARL; 12V 1
28610‑46040 B, 3B..BJ40, 42, 43, 45, 46..GEN, EUR; 24V 1
28610‑46041 B, 3B..BJ40, 42, 43, 45, 46..GEN, EUR; 24V 1

28610‑57070 B, 3B..BJ4*..GEN, ARL; 12V, SUB 1
28610‑57070 B, 3B..BJ4*..GEN; 12V, SUB 1
28610‑57080 B, 3B..BJ40, 42, 43, 45, 46..GEN; 24V, SUB 1
28610‑57080 B, 3B..BJ40, 42, 43..GEN; 24V 1

This diagram is for a 1979 North-American BJ4* which uses a DIFFERENT RELAY:
28610 RELAY ASSY, GLOW PLUG
28610‑46040 B..BJ40 1

I suspect that if I ever convince you to open your 46030 relay, you'll find the S terminal unconnected, at which point we'll have proven that all 12V trucks do not use the S terminal.

The only question left, then, is whether 24V trucks actually use the S terminal or not.

(And in deference to HJ47, I won't speculate on similarities in the harnesses between 12 and 24V trucks, perhaps dictating the presence of an "extra" terminal :D)
 
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....
...I must check back to see which relay HJ47/Chris opened up.

Well I've spent a while searching Chris's magnificent build thread (anyone who hasn't seen it should take time off work for a good squizz) and I've found that the relay he took apart there was part number 28610-68010. And of course the reason for my search is that I remember him saying he couldn't could see anything connecting internally to his S terminal either.

So that's both 28610-46031 and 28610-68010 relays with it confirmed that nothing is connected to their S terminals (that one can see).

And then there is also my 28610-46030 relay BEHAVING as though nothing is connected to it (while I'm reluctant to actually take it apart and check that for sure).

PS. Here's the link to one of the best build thread EVER:
https://forum.ih8mud.com/fj45-owners-club/131671-hj47-welcome-here.html

Yep, you've got it right. Hmm, looking at the diagram again (and I think this may be your point), as the diagram is drawn it appears that any time the glow relay is switched, the starter is going to crank... lol, just one more typo, among many! I will edit my prior post.

Yeah. That's why I was saying "she would start cranking whenever you glow" with that wiring diagram.


....You know what I noticed though?? the "different part number" for the Canadian trucks is the SAME part number as GEN BJ4*s which are 24V. So it seems this "different" relay isn't so much a special version for the CDN market with the momentary glow switch, but rather may just be the 24V variant of the same relay!......

So that means we can "extrapolate" our findings to another 2 relays. (The 24V cousins of 28610-46031 and 28610-68010) :D - edit later - Seems like statement was premature.- Later posts in this thread suggest 24V glow plug relays are indeed quite different from their 12V cousins and have internal wiring actually connected to their S terminals!



...I suspect that if I ever convince you to open your 46030 relay, you'll find the S terminal unconnected, at which point we'll have proven that all 12V trucks do not use the S terminal.

The only question left, then, is whether 24V trucks actually use the S terminal or not....

You won't. ......................and

I bet the 24V relay-cousins are of identical design except for coping with the higher voltage. So 24V coil(s) instead of 12V but little else, if anything, different. Edit later: Thank heavens I don't bet money cos now (later on) I believe I'm wrong here!

:cheers:
 
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I don't know if my S terminal is connected to anything or not. Years ago when I opened the relay to clean and polish the contacts I never thought to look. The truck is now parked at a friend's place in 2 feet of snow so I don't feel a strong incentive to open up the relay right now.

I can see the logic behind the S terminal being used to bypass the glow controller, though (if it is actually wired that way). The plugs are I believe rated for 20.5V and the glow controller is actually a resistor that prevents prolonged overvoltage to the plugs. When you engage the starter the draw by the starter pulls the system voltage down to or under 20V so you don't need the controller while the engine is cranking.

I am going to try to post some more FSM wiring diagrams.
 
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I don't know if my S terminal is connected to anything or not. Years ago when I opened the relay to clean and polish the contacts I never thought to look. The truck is now parked at a friend's place in 2 feet of snow so I don't feel a strong incentive to open up the relay right now.

I don't blame you for not opening it up again now. I don't even have cold weather to contend with here yet I still don't want to open mine.

...I can see the logic behind the S terminal being used to bypass the glow controller, though (if it is actually wired that way). The plugs are I believe rated for 20.5V and the glow controller is actually a resistor that prevents prolonged overvoltage to the plugs. When you engage the starter the draw by the starter pulls the system voltage down to or under 20V so you don't need the controller while the engine is cranking....

Hey. That was exactly my thinking while Drew was looking inside his relay quite a few months back.

And I took a lot of convincing then that Toyota hadn't really gone down that route with their "as-built" wiring on our trucks.

(And of course we know that you have the 20.5V plugs because you have 24V electrics compared to our 12V electrics.)

I don't know what the problem is but I don't seem to be able to make attachments any more. I click the button and shows it being activated but then nothing further happens.

:hmm: Strange. - I just tried, and I can still upload attachments so the MUD site doesen't seem to be the problem!
You sure your file size isn't too large?
 
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I don't think it is the file size, it won't even let me get to the point of trying to attach a file. I have 19 attachements stored for 1.45mb, maybe that's the problem even though a silver star is supposed to let you store an unlimited number? Waiting to hear back from a Mud moderator.
 
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Hey, just noticed this - great idea to start this thread Tom! I look forward to discussion this topic, and you and Armaurer have laid out the picture pretty well I think.

When I took my glow relay apart, it looked pretty much the same as the one Amaurer pictures in his post. The 'S' terminal blade does very much appear to be simply riveted to the fiber board, with nothing connected to it. I found this very puzzling, as I couldn't understand how it was supposed to function, given that the other heavy wire, the 'return' from the glow controller, was connected to it. When I came across the diagram showing the internal configuration of the relay in the HJ45 in a green cover FSM published in 1981, I assumed that the manual was showing this set up correctly, that the terminal was connected in some manner that wasn't visible. I hypothesized that the fiber board might have a conducting layer inside it, or something like that.

Based on the diagram of the relay from the HJ45, I constructed a theory as to how the relay operates, namely that there were two shunts within the relay, one operated by the 'G' circuit, and energizing the glow controller and plugs through the 'G' terminal, and a second shunt, controlled by the black-white stripe wire from the starter switch, which gave subsequent glow while cranking the starter and feeding through the 'S' terminal. These seemed logical to me, more so than accepting that there was a terminal doing nothing to which one of the heavy wires in the glow system was attached.

So, theories are nice, and was was defending mine against Armaurer, not with much grace I might add, and realized that it would be best to test the theory. So, meter in hand, along with a couple of test leads, I ventured out into the -14˚F weather and ran a few tests on my relay, disconnecting the glow circuit leads from 'G' and 'S' terminals, and then energizing through both the glow and starting circuits to see what happened. The result? Both starter and glow circuits energize the relay, through the white-green wire (glow) and black-white wire (start). Both energize the relay, however voltage only comes out via the 'G' terminal. The 'S' terminal does nothing. Armaurer was correct!:clap:

Still this is puzzling to me, in terms of the design, and it terms of the apparently 'erroneous' illustration. More on that in the next post, as I thought I'd post up a couple of pictures of my truck and my glow relay. In case anyone is wondering, I relocated my glow relay, along with the starter relay, out in the engine bay to simplify things and shorten the wiring. I also didn't like having the relays located in the passenger foot well, where they were vulnerable to an errant kick.

EDIT: I now notice that my relay is a different part number than the one Tom pictures in post #1. I imagine they are much the same internally.
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Now, there has been mention about the mythical momentary glow switch on Canadian trucks - I have seen these switches on the dash of several trucks, they are a factory switch, and nothing mythical about them whatsoever. They associate to the 'cold weather spec.' package, along with a pull down fabric shield to go in front of the radiator and a few other bits. They work as follows: glow the system, go to start, and after the engine is running, the momentary switch on the dash can be pressed at any time to manually add additional glows. Just like the 'wilson switch'.

There was mention of a curiosity to see the inside of a 24v relay. Well, I happen to have one, 28610-46040 (from a 1979 BJ40 I believe), so feast your eyes on the photos below, with cover on and off. Excuse the slightly blurry pictures - it was hard to not get blurriness for some reason. Lo and behold, it has two separate shunts. The 'B' terminal is the middle one. I haven't bothered to test it to see which one's 'G' and 'S' are, however it is pretty clear that both the terminals are connected and can be energized. This 24v. relay would work exactly as I theorized in regards to the diagram from the HJ45. Looking again at that wiring diagram, I note that it says "12v or 24v" on the diagram at the battery. Though I hadn't heard of 24v HJ45's I guess they must exist in some markets and conclude that the wiring shown for the internals of the glow relay is for the 24v. version. So, the wiring diagram isn't in error except that they didn't make clear that the glow relay schematic was for 24v. Perhaps that's why later wiring diagrams don't show the internal wiring for the glow relay, as it is different for 12v and 24v. That's my new theory anyhow - have at it! I'm feeling like my faith, based on experience, in the accuracy of Toyota FSM, is still worth keeping. They are certainly better than the alternatives, like Haynes, etc, even if they have the odd error and typo., or murkily explained section

My other thought about the seeming uselessness of the 'S' terminal in 12v applications - could this arrangement be necessary to keep the glow controller wired in parallel with the glow plugs?
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......The 'S' terminal does nothing. Armaurer was correct!......

Cool.

....I thought I'd post up a couple of pictures of my truck and my glow relay.................

That truck looks GREAT Chris. You can be rightly proud.

KOOTENAY KRUZER has Emailed me some interesting glow/start wiring diagrams that I want to post up here. He has also made an interesting observation on his Canadian BJ40 that raises a question about the accuracy of "my diagram" in post #1.

But I've got to go out to the movies with the family at the moment so I'll get stuck into that when I get back.

(Might have to do some tests on my truck too - but it is raining in my workshop now. :D)

:cheers:
 
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:clap::clap::clap:

This is great, I think we're close to a Grand Theory of Everything for toyota glow relays.

HJ47th appears to have confirmed that the "SUB" part numbers are electrically identical to the primaries. He's also demonstrated that the 24V relays are a different animal entirely, which removes some of the confusion over the wiring diagrams (minor typos excluded, of course). Granted, there is still not a 12V diagram that correctly shows the relay internals, but if you have a 24V truck then you're all set!

My summary, then would read: the S terminal is used in 24V trucks by way of an electrically and mechanically independent relay inside the "glow relay", but is entirely unused in 12V trucks. Toyota wiring diagrams are accurate except for minor typos for 24V trucks but, when showing internal relay construction, are not accurate for 12V trucks.

BTW, HJ47th, that is a beautiful pickup. I very much wanted a blue 40 but then the time came I took what I could get. VERY nice!
 
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