What happened here... glow plug resistor bypass?

[Mainsail]

I have exact same setup as in post nr.1 But im still getting 24v to my glow plugs.What did i do wrong?

If the GPs are powered off the big bus bar behind the aft battery, you did it way wrong. You want to use the little bus bar just above the GP relay as shown in the OP's pictures.

If your GPs are getting power from the little bus bar already, then something is wrong upstream. Follow the wire from the little bus bar back towards the battery. Is it connected to either the front battery or the front post of the aft battery (correct) or is it connected to the big bus bar (incorrect)?

If the little bus bar has 24v then the GPs and the GP relay are running at 24v; you don't want that.

 

[MarcusOReallyus]

Incorrect terminology enhances confusion and increases mistakes.

That "little bus bar" is a junction block. The bus bars are on the passenger side of the engine compartment, where the batteries are located.

 

[SSander]

 

[rustybuttrusty]

That black wire you have going From the junction box needs to go to the front battery not the rear thats why you are getting 24 volts. The front battery is 12 volts and the rear battery is 24.

 

[SSander]

oh,thats great.This wire has been there like that when i got the truck,that explanes two sets of glow plugs going bad in 8 months.

 

[Mainsail]

That black wire you have going From the junction box needs to go to the front battery not the rear thats why you are getting 24 volts. The front battery is 12 volts and the rear battery is 24.

Uh...no. Coming off that terminal is 12V, coming off the aft terminal is 24V (and providing 24V to the bus bar).

 

[MarcusOReallyus]

Uh...no. Coming off that terminal is 12V, coming off the aft terminal is 24V (and providing 24V to the bus bar).

Yep, that's correct. That should be 12v. Those batteries are in series. Those are lousy terminals, and you have unprotected hot leads laying across grounded battery hold-down, but the wiring is correct as far as which terminal is connected where.

So you have 24v at the junction block? Then you should have 24v on all your 12v circuits, and should be frying light bulbs, etc. Something is not right.

Where are you putting each of your meter leads?

 

[Tinstar]

Just put it back to stock configuration.

So much easier

 

[Dirty1]

Yep, that's correct. That should be 12v. Those batteries are in series. Those are lousy terminals, and you have unprotected hot leads laying across grounded battery hold-down, but the wiring is correct as far as which terminal is connected where.

So you have 24v at the junction block? Then you should have 24v on all your 12v circuits, and should be frying light bulbs, etc. Something is not right.

Where are you putting each of your meter leads?

This is relevant to what I am experiencing as well. I am showing 24v at the junction block. When I tested this, the leads for the multi-meter are on the junction block and then grounded it out to the firewall. The batteries are wired properly, according to the pictures above, and the lead for the glow plugs is coming off of the rear negative terminal.

When I put my mutil-meter on the positive and negative terminal of the front battery, I am showing 24v. This is also true for the rear battery. I am showing 24v at the ends of the glow plug leads at the engine. I have not done a resistance check yet.

I have not had anything else blow out on the truck, except my glow plugs. I replaced them earlier this year but now they are not working.

I am out of ideas, but a search led me to this thread.

Thanks for any insight!

 

[MarcusOReallyus]

LEt's do this: get a voltage measurement on each battery separately. Completely disconnect them - both batteries, both + & - terminals - and measure the voltage between the posts. You are measuring each battery separately. No connection between them, no connection to the truck.

Please let us know what you find.

 

[Dirty1]

Sorry for the delay. I am a knucklehead! I had the wrong setting on my multi-meter. I am showing 12v at both batteries when disconnected. I am also showing 12v at the junction box when the batteries are connected. I have to wait until my wife gets home to help me test out everything else. I will keep you posted.

 

[fitz]

Dirty 1,
I'm glad to see that my old truck is still around.
If you need a truck to use as a reference point, let me know. My M1028 has a stock electrical system except for the glow plug resistor bypass.
If need be we can park the trucks side by side and measure voltage points on mine to trouble shoot your truck.
I'm in southern Mass on the Rhode Island border.
I'd be glad to help.
Fitz.