Internal wiring of BJ40/BJ42/HJ42 glow relay (Manual glow) (2 Viewers)

[Henry James the 47th]

".. I very much wanted a blue 40 but then the time came I took what I could get. VERY nice! "

Hey there's always the 'strip down to the last nut and bolt and repaint' option for your truck too - then you could have any color you want! My truck arrived in the tan/beige color, and tuned out to have an un-original cab, which was green underneath. I didn't like either color much, so I went with the Nordic Blue. I wish my body work skills were better, but at least there's no rust anywhere.

Okay, sidetrack off.

 

[KOOTENAY KRUZER]

Henry James the 47th -

Thanks for posting the picture of the 24V relay. If I remember I will check the p/n of my relay next time I am near my BJ40, but at least I don't feel I need to be kneeling in the snow to pull mine for this thread.

 

[lostmarbles]

Gee whizz. So much "food for thought" now.

My first step was to look at the EPC and check where these glow plug relays were fitted. (Not sure why really - But at least it shows us where replacements are available from.)


That's:

• 28610-46030 subs 28610-46031 (12V) as used on my 1979 Australian 12V BJ40 and Amaurer's 1982 New Zealand 12V BJ42
• 28610-46040 subs 28610-46041 (24V) as used on KOOTENAY KRUZER's 1979 Canadian 24V BJ40
• 28610-68010 (12V) as used on Henry James the 47th's 1982 Australian 12V HJ47

And this is what I've found:

 

[lostmarbles]

And lastly - This one



And in light of what Chris has shown with that 24V glow plug relay - and the fact that it seems to be the 24V "cousin" of my relay - I concur that the peculiar "unconnected S terminal phenomena" maybe limited to 12V cruisers. (Perhaps the same wiring loom is used in 12V and 24V models?)

Anyway - I'll try and post the diagrams that Wayne (KOOTENAY KRUZER) sent me here: (They're interesting too.)

This one is from the 1977 Chassis and Body Repair manual



And this one is from August 1980 B-series engine manual



I've asked Wayne to Email me "higher kilobyte" versions (if he can) because I'm having trouble magnifying and viewing these.

Edit: Wayne supplied me with larger files so on 4 Jan at 7am I replaced these last 2 images with ones that are easier to read.

 

[Henry James the 47th]

I couldn't sleep thinking about this odd 'S' terminal, and then I had the light go on. Actually, Tom seems to have slightly beaten me to the punch here, but a is a so here goes....

The issue was confounding because I couldn't see the sense in manufacturing a relay with a dummy terminal, and then hooking a wire to it. From a manufacturing perpective, why spend the money? Why design something like that?

Now, Tom (Lost Marbles) brought to my attention a misapprehension that I was laboring under, namely that the controller was wired in parallel, just like the glow plugs. Well, it isn't - it's wired in series, to the glow plugs, which are themselves wired in parallel. Thus a whole bunch of stuff was suddenly cleared in my mind - - though this dummy 'S' terminal was still making no sense.

Drew, in a discussion on another thread had suggested the harnesses were used in both fixed delay and Superglow applications, which i knew to be wrong. However, thinking about the wiring diagram, and how it uses the phrase '12v/24v.' to label only the battery (the rest of the wiring being the same for both applications obviously), and then casting my mind back to the BJ40 harness I took all apart, a 24v. harness, and remembering how it was pretty much the same as my own HJ47 harness, save for the added resistor for the cig. lighter and the transformer for the radio - - well, clearly Toyota does use the same harness for 12v. and 24v. applications. I'm sure they do this to streamline production and realize economy. Drew was correct about the multiple use of one harness.

In other words, the base harness must be a 24v. harness, and that is really what was illustrated in the HJ45 wiring diagram - including the internal wirng for the glow relay. For 12v. applications, a 12v. glow relay is fitted, and in order to deal with the cable end (the black-yellow returning from the controller and going out to the plugs) that attaches to the functional 'S' terminal on a 24v. relay, Toyota simply specifies a relay that has a dummy terminal put on it. That way the cable has somewhere to terminate to, instead of being left loose where perhaps it might otherwise find a means to ground out somewhere (or would simply look untidy, I don't know). It must be cheaper to manufacture the specific relay like that than to make two separate harnesses.

What this means in a 12v. application is that the Black-yellow cable can be disconnected from the 'S' terminal, carefully wrapped to make sure it can't ground out, and the operation of the glow system will continue just fine. This also means that there might be some options for glow plug relay replacement, which would retain use of the glow controller, a consideration given that most of these older glow plug relays are obsolete out of Toyota, and once our existing ones die, we need some options for replacing them.

Well, I think I can sleep now. Tomorrow I'm going to test this idea out by unhooking the black-yellow from the 'S' terminal and see how things run. I'm confident nothing will change. I wish I had known this when I wired my truck, as it would have saved me a little work to leave that wire off.

 

[lostmarbles]

....in order to deal with the cable end (the black-yellow returning from the controller and going out to the plugs) that attaches to the functional 'S' terminal on a 24v. relay, Toyota simply specifies a relay that has a dummy terminal put on it. ............

Heck. I think we've nailed it here Chris.

I believe we've finally solved "the mystery of the S terminal" for 12V diesel-cruiser owners!


................................. But I wonder how many others besides you, me and Drew have really been lying awake at night thinking about it



PS. I think I'll eventually create an upgraded version of that wiring diagram in post #1 to include these 12/24V differences and perhaps even list some part numbers. (That's the trouble with my diagrams. They're "living things" and always changing.)

(I'm learning soooooo much here!)

 

[GregFrench]

What this means in a 12v. application is that the Black-yellow cable can be disconnected from the 'S' terminal, carefully wrapped to make sure it can't ground out, and the operation of the glow system will continue just fine. This also means that there might be some options for glow plug relay replacement, which would retain use of the glow controller, a consideration given that most of these older glow plug relays are obsolete out of Toyota, and once our existing ones die, we need some options for replacing them.

Well, I think I can sleep now. Tomorrow I'm going to test this idea out by unhooking the black-yellow from the 'S' terminal and see how things run. I'm confident nothing will change. I wish I had known this when I wired my truck, as it would have saved me a little work to leave that wire off.

So I could have left that wire off when I re-wired my system last night? I guess that was a good question in my other thread after all (just a day premature)

 

[Henry James the 47th]

Well, if my late-night crazed ramblings actually prove to be right, I am left with another question: why is the 24v version designed the way it is? At first, my thought was: 2 shunts in the relay, 2 times the voltage, 2 circuits, 2 batteries... makes sense I guess.

But then I considered the way this seems to operate: when the key is in 'G', only that circuit is being energized, through one shunt in the relay. When you turn the key to 'ST' from glow however, the 'G' circuit from the ignition is no longer powered, and the black-white stripe wire from the 'ST' circuit apparently energizes the relay to keep glow on while the engine is cranking. Now, since the relay shunt is apparently used in a one-at-a-time fashion, why the need for two separate shunts in the 24v. version?

Maybe this isn't quite so 'figured out' yet - does someone have a good explanation as to why the relays would be configured differently? I think it would be good to set up a test with the relay I have (not sure if it actually works or not, though the insides looked clean), to see where the power comes out when the 'G' and 'ST' circuits are alternately energized. If I have a chance later today, I'll see if I can do that.

GregFrench, I am pretty sure that the glow system will work just fine in a 12v. application with the black-yellow wire not connected to the 'S' terminal, but I would say that at this junction we're still dealing with a certain amount of speculation here (if not outright delusion ), so I can't make a recommendation to do that disconnection quite yet. I'll try it with mine and let y'all know what happens. You could experiment with yours too, or play it safe and wait to see what I find.

 

[lostmarbles]

Well, if my late-night crazed ramblings actually prove to be right, I am left with another question: why is the 24v version designed the way it is? At first, my thought was: 2 shunts in the relay, 2 times the voltage, 2 circuits, 2 batteries... makes sense I guess.

But then I considered the way this seems to operate: when the key is in 'G', only that circuit is being energized, through one shunt in the relay. When you turn the key to 'ST' from glow however, the 'G' circuit from the ignition is no longer powered, and the black-white stripe wire from the 'ST' circuit apparently energizes the relay to keep glow on while the engine is cranking. Now, since the relay shunt is apparently used in a one-at-a-time fashion, why the need for two separate shunts in the 24v. version?

Maybe this isn't quite so 'figured out' yet - does someone have a good explanation as to why the relays would be configured differently? I think it would be good to set up a test with the relay I have (not sure if it actually works or not, though the insides looked clean), to see where the power comes out when the 'G' and 'ST' circuits are alternately energized. If I have a chance later today, I'll see if I can do that..........

Hi Chris. I've just been given larger-kilobyte copies of those 2 wiring diagrams that Wayne (KOOTENAY KRUZER) sent me of his 24V BJ40 (which he bought new). so I've upgraded those last 2 images in post #24.

The last one there from his Engine manual is now very easy to read and contains little in the way of "Toyota errors" I think (for his 24V set-up).

I now believe that in "24V cold climate cruisers" Toyota wanted to "boost" the voltage to the glowplugs briefly while the engine is cranking and this arrangement of 2 separate pairs of contacts (with their separate operating coils) achieves this. As someone here has already noted (can't now remember who), the battery voltage is already being "taxed" during cranking so the 20.5V plugs are unlikely to receive excessive voltage by "chopping-out/bypassing" the glow controller at this time anyway. (In other words, - chopping-out the glow controller during "cranking" probably won't BOOST the voltage being applied to the plugs by much anyway - but it should at least keep them glowing well.)

I don't think Toyota wanted to go this way with 12V cruisers because:

• they shouldn't be destined for "cold climates" where starting a diesel becomes particularly difficult, and
• If the glow relays were to "chop-out" the glow controllers on both 12V and 24V cruisers, then 8.5V plugs are more likely to receive "excessive voltage" (and fail as a result) than 20.5V plugs. (Because 8.5V is just 71% of 12V whereas 20.5V is 85% of 24V)
• 24V cruisers utilise 4.5kW starters whereas 12V cruisers utilise 2.5kW starters. So cranking duration must be less in a 24V cruiser.

Well this is me just theorizing out loud anyway.. He he

Edit later (11 Jan 2009) - Still too early for me to say exactly how a 24V cruiser's glow/start circuitry is wired. And I have no access to such a cruiser (for verifying things myself) so I may NEVER know.
And at this point I'll try and add the text from the Email that Wayne sent me that supports our theory that 24V cruisers have this extra glow relay wiring. (In his Email - he said he noticed his controller starting to loose it's glow immediately he turns his key to "start"): PS. But I'm using "selective-memory" here cos you'll see he also says he can only remember cleaning one pair of contacts - which tends to refute our latest theory.

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----- Original Message -----
XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
To: lostmarbles
Sent: Friday, January 02, 2009 8:30 PM
Subject: Emailing: Glow plug relay wiring 001, Glow plug relay wiring 002


Tom,

The first picture, the one that is part of a whole vehicle wiring diagram, is from the 1977 Chassis and Body repair manual and is labelled LAND CRUISER(BJ40,43)ELECTRICAL WIRING DIAGRAM (Except USA & CANADA)

This is probably because they never imported BJs into the USA at all and the very first market test versions came to Canada in 1978 but they weren't actually on the market here 'til 1979. I bought mine in May of '79 for a trip we did in August that would have required me to carry about 70 gallons of petrol in my '76 FJ40 with a 12 gallon tank. Since we had to be self-sufficient for 2 weeks on food, booze, and spare parts as well I didn't see how I could do it with the FJ40 so I bought the BJ40 for the increased range.

The second picture is from the Aug. 1980 B series ENGINE repair manual, labelled Except BJ60 (The BJ60 system in this manual uses a preheating timer, I think it is what they call the superglow system). This one looks like it would work if there were 2 seperate coils and contactors in the relay box but I don't remember cleaning 2 sets of contactor points. I do know that the glow plug controller does not seem to get any power when the starter is cranking because it starts to dim right away when you start cranking unless you hold the manual switch closed while cranking.

Wayne
The message is ready to be sent with the following file or link attachments:
Glow plug relay wiring 001
Glow plug relay wiring 002

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And I'll add Wayne's diagram from his August 1980 B-series engine FSM to make reference to it easier:

 

[Henry James the 47th]

Well, in regards to my theory about the disconnection of the Black-yellow stripe to the 'S' terminal, I followed through with that this morning. The truck glows and starts just like normal. I went for a drive to a hardwood lumber yard, and made a couple of other stops during my journey. The system works exactly as usual. So, GregFrench, while it might be a little late in your case, you could leave off the splice and connection to the 'S' terminal.

I'm going to follow up on testing that 24v relay to see what happens. I don't have dual batteries to work with, so I'll see if it will work okay with a 12v feed.

That diagram you provided Tom, via KootenayKruzer, appears to suggest that the 'ST' circuit energizes both coils, powering both shunts therefore and outputting through 'G' and 'S' terminals at the same time. If so, that doesn't seem to jibe with the observation that the glow controller turns off when cranking the starter.

I'll see what happens when I test it...

 

[lostmarbles]

...
That diagram you provided Tom, via KootenayKruzer, appears to suggest that the 'ST' circuit energizes both coils, powering both shunts therefore and outputting through 'G' and 'S' terminals at the same time. ..

No it doesn't Chris.

Ignore those diodes. (Just pretend they're not there.)

And I'm assuming the top coil operates the top pair of contacts while the bottom coil operates the bottom pair.

And where any 2 wires "cross without joining", the diagram has one of them "looped" to show this.

And don't misinterpret any heavy "glowplug relay enclosure" lines drawn there for electrical wires. (To avoid this confusion, I've been drawing these lines in "light blue" when I draw my own copies of the Toyota diagrams)

Here. Does this tampering make it easier to read?



PS. I STILL DON'T YET KNOW FOR SURE THAT 24V CRUISERS ARE ACTUALLY WIRED THIS WAY!

 

[Henry James the 47th]

That diagram is definitely more in line with the theory, however are you certain there is no diode inside the relay? I assumed the function of the diode would be that when the glow circuit is energized, there is no current going into the 'ST' circuit via the glow relay. That's what i presumed the diode(s) were for, since both the white-black 'ST' circuit wire and the white-green 'G' circuit wires operate the same shunt inside the relay (in 12v. applications). The diodes, where illustrated, always seem to show the direction of flow being from the black-white INTO the relay, and thus blocked from going the other way.

Why do you suppose these diodes are illustrated if they are not actually present?

Lastly,

"And where any 2 wires "cross without joining", the diagram has one of them "looped" to show this.

And don't misinterpret any heavy "glow plug relay enclosure" lines drawn there for electrical wires. (To avoid this confusion, I've been drawing these lines in "light blue" when I draw my own copies of the Toyota diagrams)"

Thanks - I was under no misapprehension concerning those points.

 

[lostmarbles]

...are you certain there is no diode inside the relay?....

No. In fact I believe there ARE diodes inside all of our glow plug relays. (Yours and mine included.)

..I assumed the function of the diode would be that when the glow circuit is energized, there is no current going into the 'ST' circuit via the glow relay. That's what i presumed the diode(s) were for, since both the white-black 'ST' circuit wire and the white-green 'G' circuit wires operate the same shunt inside the relay (in 12v. applications). The diodes, where illustrated, always seem to show the direction of flow being from the black-white INTO the relay, and thus blocked from going the other way. ...
Why do you suppose these diodes are illustrated if they are not actually present?

I thought like you too - until Amaurer/Drew put me straight.

Apparently the diodes were fitted simply to stop "sparking at the contacts/points". (That's my interpretation - so Drew can jump in and correct me if it's a bad one.) And these are called "clamping diodes". And as such, they serve no purpose as far as understanding how the circuitry works.



PS. I think we have to put ourselves in Toyota's shoes back in 1977 to really understand what's going on here.

I suspect that back then, the EDIC was "advanced technology". And that they wanted to protect this "new technology".

How better to protect it from copycats than to cause confusion in their FSMs as to how it works?

And if you're thinking the "glow relays" are difficult to understand - start looking at the EDIC relay and how it is connected to the EDIC motor and try working THAT out. (I've already started but haven't got far! Might need more of Drew's help there )

 

[Henry James the 47th]

"And if you're thinking the "glow relays" are difficult to understand - start looking at the EDIC relay and how it is connected to the EDIC motor and try working THAT out. (I've already started but haven't got far! Might need more of Drew's help there ) "

Anther day, and another thread I guess.

Clamping diodes eh? Hmm, I will see what I can find out about that.

 

[amaurer]

Clamping diodes eh? Hmm, I will see what I can find out about that.

Google's very first link just happens to be from an automotive perspective and is quite good for the casual reader:
http://www.autoshop101.com/forms/hweb2.pdf

Start at page 11.

To be clear - I verified that the diodes present in the 12V relay are in clamping configuration. I don't have a 24V relay to verify if there are any diodes at all, or, if there are, what configuration they're in.

 

[KOOTENAY KRUZER]

I don't clearly remember the inside of the relay from when I cleaned the contacts (that was over 10 years ago) but there is a certain feeling of familiarity to HJ47th's picture of the 24V relay.

If both coils are energized from the ST terminal I think the resistance of the glow controller would mean very little current would flow through the controller if the other circuit is providing a low resistance bypass so the function would be essentially the same.

When I cleaned the contacts I used a fine grit diamond nail file to file away the pits and spikes. The contacts still stuck closed as often as not, so then I polished them with crocus cloth. The relay has been working fine ever since.

Crocus cloth is similar to emery cloth except it is thinner and is impregnated with jeweller's rouge instead of coarse emery grit.

 

[Henry James the 47th]

Google's very first link just happens to be from an automotive perspective and is quite good for the casual reader:
http://www.autoshop101.com/forms/hweb2.pdf

Start at page 11.

To be clear - I verified that the diodes present in the 12V relay are in clamping configuration. I don't have a 24V relay to verify if there are any diodes at all, or, if there are, what configuration they're in.

Hey thanks! That was a very helpful article for a non-specialist such as myself. I think I find the term 'de-spiking diode' more helpful, as I was thinking the term 'clamping' related to the magnetic pulling over of the switch contact, which is hardly what the diode is doing. I now understand the function of the diodes in the relay, and would like to make some of the relay function tests suggested in the article, however they note that for relays with de-spiking diodes, it is best to use an analog meter, which draws a slight amount of current, instead of the digital type. Too bad my analog meter died last year.

Another interesting point the article brings up is that the fact that the relay 'clicks' is no guarantee that it is functioning correctly, an assumption I have long made (based somewhat on the testing procedure Toyota gives in the FSM for most relays).

 

[lostmarbles]

Hmmmm.

I kind of like the idea of putting together 2 separate start/glow wiring diagrams (next series of rainy days when I can't work outside): - One for 12V BJ40, BJ42 and HJ47s and the other for 24V BJ40 and BJ41s. (I don't think a BJ41 was ever available in 12V and I don't think a BJ42 or HJ47 was ever available in 24V ..... although I've never researched this.)

The information gathered here in this thread (thanks to one and all) is already enough to keep me going for a long time........................But .....woke up this morning with still more questions.

And, by the way, I took a look at the EPC too to obtain the following data on glow controllers for our landcruisers:
28550-46021............B 12V (I think this is my 1979 BJ40)
28550-46030............B 24V
28550-46031............B 24V
28550-57010............B 3B 12V
28550-57020............B 3B 24V
28550-47020............H 12V
28550-47021............H 12V
28550-47030............H 24V
28550-47040............2H 12V (Henry James the 47th's HJ47)

And I think we can assume (from the way the Toyota parts numbering system seems to work) that 46031 is merely a "substitute" for 46030 (in other words they are interchangeable). Similarly with 47020 and 47021. So really I suspect there are just 7 different glow controllers here.

But back on the subject of "glow relays", I was thinking this morning about why Toyota would choose to use a different one for the 6 cylinder engine compared to the 4 cylinder. Surely the 6 (with its 2 extra plugs) simply draws more current through the relay contacts? And if Toyota had to install beefier contacts for the 6 cylinder - why not use the same relay (with beefier contacts) for the 4 cylinder models too?

At the very least - surely the 28610-68010 2H relay must be able to be used instead of any 28610-46030 (or 28610-46031) B/3B relay? (All 12V) That's assuming the 68010 2H relay simply has beefier contacts!

Or maybe the "clamping diodes" within these relays need to be sized/selected differently depending on the different current-draws? (In which case these diodes must be more important than I've imagined them to be thus far.)

Thoughts??

 

[american psycho]

I don't think a BJ42 or HJ47 was ever available in 24V .....

I bought and sold 2 24V 1983 BJ42s here in Switzerland in the last year.

Didn't see a FSM for either, and haven't looked, because I've got a 1988 24V BJ70 to scrap now.

 

[lostmarbles]

I bought and sold 2 24V 1983 BJ42s here in Switzerland in the last year.

Didn't see a FSM for either, and haven't looked, because I've got a 1988 24V BJ70 to s**** now.

So BJ42s are indeed available in 24V! Thanks for correcting that misapprehension of mine Jon. (There are many more too I know!
For instance I've never really known where BJ43s and BJ44s fit into the scheme of things.)


PS. Tell you what - I might start using the term "BJ4#" more. The EPC often does that and it certainly makes life easier when you're unsure of the full extent of which models you're talking about.