glow relay, indicator

[amaurer]

two questions, re 1982 BJ42:

1) where is the glow relay located? in the cab or engine compartment?

2) how do you remove the glow indicator (coil type) from the dash? I doesn't seem to be a normal panel mount type fixture, as the front doesn't screw off....?

 

[Henry James the 47th]

two questions, re 1982 BJ42:

1) where is the glow relay located? in the cab or engine compartment?

2) how do you remove the glow indicator (coil type) from the dash? I doesn't seem to be a normal panel mount type fixture, as the front doesn't screw off....?

I believe the glow relay is in the passenger foot well, next to the starter relay. They both have some thick wires going to them and are about the same size. Both usually have printed labels on them as to what they are.

The glow indicator, coil type - I think you might mean the 'glow controller', which has a wire coil in front of a little mesh screen you can see through (and a pair of heavy gauge wires connected to it). The front mounting ring does unscrew - yours might be on tight or perhaps has suffered a bit of oxidation making it tough to remove. You can try rotating the controller body behind the dash as you twist the mounting ring the other way. It unscrews in the same direction as a regular nut, counter-clockwise.

 

[amaurer]

Cool, thanks, I got it off. Now I have even more questions. My symptoms are:

a) glow "controller" or "indicator" or whatever never glows...
b) hard starting after a cold night, even with a 20 second glow.

I did some poking around and I find:

a) I get 1 volt measured across the glow controller/indicator
b) I get 7-8 volts across the glow plugs
c) I get 12V across the battery

High school physics tells me that you have only 1/3 of the "heating" power at 7volts as you do at 12volts, so this may be my starting problem. I know from reading other posts that this is probably a bad ground... but which grounds are the usual suspects and what is the best way to "improve" them??

See electrical diagram below, I'm wondering how things are layed out INSIDE the relay...? I gather that both wires from the ignition switch go to the relay coil, that much is easy. Also its easy to see that the "S" terminal on the relay gets switch on to Batt + (because this feeds the glow plugs).

But what does the G terminal do?! It the return from the glow controller; does it just switch to Ground (if so, what a silly design, why switch it twice?!)? Does the glow controller actually control the relay in some way??

 

[Henry James the 47th]

I've spent some time staring at the exact same section of the wiring diagram myself lately. There seems to be an earlier type of glow relay with 5 wires instead of 4. In BJ40's, the extra wire was involved in a simple indicator light ("glow") circuit. in the one shown in the picture you attached, which is the same as for my 47 series, the extra wire is involved in the 'glow controller'.

My glow controller is brand new and hasn't had current through it yet, so I'm pretty clued out as far as operation is concerned.

Later vehicles without a glow controller or duration light have 4-wire glow plug relays; those trucks with later Superglow systems have two glow plug relays, both 4-wire, and a more complex timer.

It seems to me that the controller/light on the 5-wire designs must send a different signal after a time, though voltage drop or rise, something like that, back to the glow plug relay, which in turn causes it to change what it does in some way. I'm really not sure either what the 5th wire does, and I agree that it's odd that the FSM wiring diagram does not show the internals of the 5-wire relay, whereas for all the later 4-wire type the internals are illustrated.

 

[Ron R]

Have you measured over the relay, from terminal B to terminal S?
Should be virtually 0 V.
If not, the relay is faulty.
If you measure 0 V then check voltage at B under load (glowing) If this is not more or less equal to batt voltage at that same moment: check the wire between battery and terminal B (properly connected?)
Also check terminal S under same conditions. If that terminal has good voltage check the wire inbetween S and the glowplugs.
There must be a resistance somewhere (broken/damaged core?)

 

[amaurer]

B (battery) to S (plugs) I get about 2V.

I also checked B (battery) to G (indicator) and got 0V.

Now, you may be thinking to yourself "ok, sounds like the B-S line is broken and dropping 2V it shouldn't be". However, I don't think it could be this simple.

If both lines dropped zero volts, then B and S would both be at 12V or so, and there would be 0V across the "glow controller", meaning it would never start glowing...

Does anyone's glow controller actually function? Could you measure the voltage across it when you energize the plugs?

Also, what is a typical voltage found at the plug for a 3B with manual glow? Should I be aiming for 12 full volts?

 

[Ron R]

B (battery) to S (plugs) I get about 2V.

I also checked B (battery) to G (indicator) and got 0V.

Now, you may be thinking to yourself "ok, sounds like the B-S line is broken and dropping 2V it shouldn't be". However, I don't think it could be this simple.

If both lines dropped zero volts, then B and S would both be at 12V or so, and there would be 0V across the "glow controller", meaning it would never start glowing...

AFAIK the "Glow Controller" and the plugs are in parallel. As soon as the controller glows then the plugs should be 'glowing' as well.
At that moment you should start cranking.

And if you have a drop of two volts in the relay, and you're measuring about seven volts over the plugs, you still are loosing about three volts somewhere, meaning there is something going on somewhere.
Keep in mind that the glowcontroller is not quite different from an resistor or a bulb. You should find some resistance across it (hence a voltagedrop) otherwise it would never glow.
Therefore I am still conspecious about the relay.

 

[Joe Egolf]

Mine does not glow either,never has , but I can start her up every time -so fsr ???

 

[amaurer]

AFAIK the "Glow Controller" and the plugs are in parallel. As soon as the controller glows then the plugs should be 'glowing' as well.
At that moment you should start cranking.

And if you have a drop of two volts in the relay, and you're measuring about seven volts over the plugs, you still are loosing about three volts somewhere, meaning there is something going on somewhere.
Keep in mind that the glowcontroller is not quite different from an resistor or a bulb. You should find some resistance across it (hence a voltagedrop) otherwise it would never glow.
Therefore I am still conspecious about the relay.

I'm not convinced the controller IS in parallel with the plugs. Looking at the diagram, the controller is essentially connected between the busbar and the relay G terminal. If this was a simple parallel arrangement, then it would be attached between busbar and GROUND. Also, given that theres no voltage drop between 'B' and 'G' it looks like the G terminal get switched to battery +, so in effect the controller is hooked up between Battery + and the busbar. WTF?

Yeah, I'm still losing some juice somewhere. I don't really know what the voltage across the plugs was at the time I made the relay measurements, as the drop changes as the plugs warm up and the current changes. 3V is probably more than I'm actually seeing; I think I have to track down 1-2V in addition to the 2V relay drop. I think thats a separate issue though, I have to figure out whats up with this relay!!

 

[Ron R]

I'm not convinced the controller IS in parallel with the plugs. Looking at the diagram, the controller is essentially connected between the busbar and the relay G terminal. If this was a simple parallel arrangement, then it would be attached between busbar and GROUND. Also, given that theres no voltage drop between 'B' and 'G' it looks like the G terminal get switched to battery +, so in effect the controller is hooked up between Battery + and the busbar. WTF?

I'm afraid I have not expressed myself correctly.Probably you've noticed English is not my native tongue
What I mean is that, when the plugs get juice, the controller gets it as well, at the same time. The plugs (the busbar) act as ground for the glowcontroller.

Yeah, I'm still losing some juice somewhere. I don't really know what the voltage across the plugs was at the time I made the relay measurements, as the drop changes as the plugs warm up and the current changes. 3V is probably more than I'm actually seeing; I think I have to track down 1-2V in addition to the 2V relay drop. I think thats a separate issue though, I have to figure out whats up with this relay!!

Is it possible to open the relay without destroying it? Maybe you can find the problem inside (burned contacts?).

 

[amaurer]

I'm afraid I have not expressed myself correctly.Probably you've noticed English is not my native tongue
What I mean is that, when the plugs get juice, the controller gets it as well, at the same time. The plugs (the busbar) act as ground for the glowcontroller.

Your English is just fine, this is a complex thing to explain over the 'net. What I'm trying to say is that the busbar CAN'T act as a ground because the busbar is at 12V. I'm ending up with 12V on the relay side of the controller, and 12V on the busbar side of the controller, and thus no current flow through it!! How the hell is this thing supposed to work!?!?!?

Is it possible to open the relay without destroying it? Maybe you can find the problem inside (burned contacts?).

That is exactly tonight's task! The cover is a metal cover held in place with tabs bent down over the relay base. Should come right off.

 

[amaurer]

Amazing!! I got the relay open, the BY line (terminal S) is attached to NOTHING! (There is no doubt about this, the S terminal is attached to the fiber baseboard in the relay with a rivet and no other connections. No solder, broken components, wires, etc.)

I think that the BJ42 might share a harness with another vehicle and a different relay is used in that application wherein the BY line actually has some use.

However, this means that ALL the glow plug power needs to flow through the "glow controller" and I gather that this is the "control" function; the voltage dropped by the controller decreases as the coil warms up, in essence providing a sort of "soft start" for the plugs themselves. (Note that I find my little controller *does* light up now, having blasted a fine layer of New Zealand dirt off of the coil, heh)

I put everything back together and measured the voltages again: When first turning the key the plug-battery ground voltage measures about 6.5V and increases to about 9V over 25seconds or so. Engine grounds are good; measuring from the plug to the engine gives the same voltages as measuring from the plug to the battery -.

I really need some kind soul with a BJ42 to measure the voltage across their plugs (i.e. from busbar to engine and from busbar to battery -) AND the voltage across their glow controller... anyone anyone???



for those interested, this is the relay schematic:

 

[Ron R]

Hm, and here it's proven again. One is never too old to learn.

This the way it used to work in my old truck ( not a toyota ). But there is was a simple construction of a relay, feeding a coil (the glowcontroller/indicator) and from that coil directly to the plugs. In fact the same as you have here, but here it's more hidden.
I seem to remember that it could take up to 45 secs before the indicator started to (visibly) glow.