M1009 Starting troubles

[DonK]

I purchased my first MV last week, installed new batteries to drive it home. Ran fine for two days. Now when I try to start it the Glow Plug Light stays on as long as the ignition is on. It turns over fine. It's still the 24v system. I suspect the Glow Plug Module or Temp sensor. Then again it could be the GP relay....Any advise before I rip into it?

 

[mistaken1]

Download the manuals and follow the troubleshooting procedure in the -20.

 

[Blue2actual]

 

[DonK]

Found a bad GP relay but it still won't start, Wait Light seems to be working properly now. I think the Glow Plugs may have been cooked. 24VDC coming from the Batteries goes through the Resisters to the GP Relay. Should the voltage drop across the resisters when the circuit is closed? It should, I think...anyway the 24V feed through the GP relay drops to about 4 or 5 at the Glow Plugs. Measured one of them while cranking...Measured resistance of one of the Glow Plugs and it shows Open...Any advice?

 

[Blue2actual]

DonK, if you do a search on the site, you will find MULTIPLE threads regarding starting issues on these beasts. I've got no problem helping you find information for your truck, but some of the older, grumpier members get mad when you ask questions that can be found in the TM's or by using the search! http://www.steelsoldiers.com/cucv/62477-gp-module-theory-operation.html

You said that you found a bad GP relay-did you replace it? If you didn't, there are multiple threads about GP relay P/N ST85 at Napa that work great. I hope the info below helps.

4 seconds should be plenty long enough to fire it up cold. Pull the wires and individually test your glow plugs. Look for 0-3 ohms(good). Are you supplying them with 24v through the resistor bank, or 12v front the front battery?

If you had one bad glow plug, that's all it takes to cause the rest to go bad, when using the original 24 volts through the resistors.

The cucv cannot maintain glow plug operation, with a bad gp.(they all will burn out, if you continue to start it with one bad, with the original 24v supply) If you are not going to use the nato slave port to jump start your truck ever, you can eliminate this domino effect by changing the gp supply to 12v.(then, when one gp goes out, it won't effect the others)

 

[DonK]

Thank You Sir...I'll do more research and report back.
I was looking for some "quick fix" info and/or tips to get it on the road again quickly...

 

[Blue2actual]

I've got some family in social circle, that live in the surrey chase development off of GA 11

 

[mistaken1]

If you pull a glow plug and measure it with an ohm meter and it is open it needs to be replaced.

By a set of 8 and replace all of them then any old ones that measure okay keep for emergency spares.

I recommend AC 60G glow plugs with new terminals on the wires but you can grind the spade down from 0.250 in to 0.087 in (1/4 to 3/16) if you do not want to install new terminals.

 

[EXCG_Steve]

Hey newb, read the manual.

I bet all the GP's are bad since at least 3 were open.

I'll read thru the manual but I think we know what the problem is.

Let me know if you need help bro!

 

[DonK]

New GP Relay and Glow Plug did the trick....Thanks for the help and advice.