@ Starmilt & Phy: The black ground wire coming from the controller is grounded to some metal inches away, some other cast part of the engine. It is however pretty greasy and dirty back there; I traced it back when I unbolted the controller to check the status of the controller wires. I will disconnect this, if I can contort my hands enough, and connect it to a jumper wire and run that straight to the negative terminal of one of the batteries.

Does anyone thing that I might need to replace the starter relay/solenoid? I was looking on Napa and it looks like the part is from Mileage Plus Electrical for $18.00. I could pick this up on my way home if it might help. This one matches the one that is currently on the truck:




MPE ST404SB
NAPA AUTO PARTS

Thanks again guys for all of your help! I know we will get a solution before too long... I just hope it comes before the wife needs the truck on Sunday!

 

I don't think your starter relay would have anything to do with it.

 

No, the starter relay isn't part of the circuit. It just provides a convenient connection point to get high-amperage power for the load side of the GPR.

If getting a known-good ground to the controller doesn't fix it, I'd be thinking the controller is bad...

 

clean off those battery posts.

 

Well for $20 I replaced the starter solenoid just to be sure and, still having the same problem. So for $20, at least I know that part is new for future reference.

@Phy: The black ground wire from the controller that is connected to the manifold block has a quick disconnect and I ran that straight to the negative post on the battery and tried and still have the same problem.

The voltmeter that I used yesterday is no longer working and makes me think that it wasn't quite right to begin with. I hooked up another digital voltmeter to the battery, to both batteries and both read a bit over 12v. I then hooked up the negative to a GP and the positive to the + terminal on the battery and there is no read.... So NOW Im thinking about trying to replace the GPs tomorrow.

At this point, what else (aside from the GP controller) would/could be wrong with this system? I don't want to just keep throwing parts and money at it, I want to find the problem.

 

Well, the whole system consists of the controller, the relay, the glow plugs, the wiring harnesses from the relay to the glow plugs, and the wiring from the starter relay to the GP relay, so if you're going to change out the plugs, and you've changed the relay, that only leaves the wiring harnesses & the controller. When you change the plugs, unplug all of them, disconnect the glow plug harnesses from the relay, and then check the harnesses for continuity to ground (shouldn't be any...), and continuity between the relay end and each glow plug end.

 

I have never tested a gp with a voltmeter like that, so I don't know what it should read, if anything. If you test with the ohm meter it takes a pretty high quality meter to not just measure open and then it is 1 or 1.5 somewhere in there.

What was the original problem, in other words what did it do when it quit.

 

OK lets do some checking with your volt meter.
make sure the controller itself has a good ground.
With the key off do you have voltage at the battery terminal, you should have the same as the battery or very close.
Now turn the key on and check the voltage at the ignition terminal, the small one with the red wire. you should have voltage there.
Now hook your volt meter to a gp, it should read zero.
with a jumper wire run from the battery neg to the terminal with the white wire, The relay should click and you should have voltage to the glow plug, do not hold the jumper wire on for over 10 seconds.

 

The one I am using is a volt-ohm meter. And the original problem is that the truck would not start unless it was hooked up to the heater block for a few hours, which was telling me that the GPs were not heating up the cylinders.

I will try to run these tests before I start to change the GPs.

 

Make sure you get voltage to the gps when you manually ground it. It would do no good to replace the glow plugs it there is no voltage there.

 

@ Starmilt & Phy: THANKS so much for all of you're help. Saturday I replaced the GPs and still had the same problem, I hooked it up to the heater (temp outside on Saturday was around 42F) for a few hours and it cranked up but the WTS light stayed on the whole time, I drove it for about 5 miles. I then let it cool some and replaced the GP Controller and turned it on and the WTS light was on for about 10 seconds and then went off and the truck cranked up. I then let it sit with the hood open as the temp dropped over the evening and tried it again once the engine cooled and it started up.

Hooked it up to the block heater for the night, since the wife needed it early in the morning, and it cranked up, WTS light came on and went off and she said it worked like a champ all day.

Thanks again for all of your help and if you find yourself driving through Richmond, VA, let me by you a beer or two!

 

Hey, no problem. Glad you got it fixed.