First Post, hoping for some starter help...

[boatbuilder]

Hi guys, I have an 86 M1008 and my family and I depend on it for plowing and sanding my road. I live in Maine, and now is not a good time for it not to be starting! S

Problem- it will not turn over ( I just ran it yesterday and all was fine)
Ignition seems to work fine, glow plug buzzer/wait light work, gen lights are on, oil and 4wd lights are on.
After the buzzer/wait light go off, turn key to start and hear the starter relay in the dash click (no doghead mod), 4wd AND oil light go OUT when trying to start. Nothing from under the hood.
Also now and then starting it over the last year or two, when waiting for the glow plugs, there is a very rapid clicking sound that speeds up and then stops under the hood somewhere, and this sound is not happening now, but did not always happen.

-So I've checked my batteries, terminals, etc, ( I am a marine mechanic and electrician so i know these are satisfactory)
-I crawled under the truck tonight and Im embarrassed to say I have no idea how you guys are accessing the terminals on the starter solenoid or starter to jump or test at that location. I can barely touch the main battery connection, and cant even feel the solenoid terminal let alone get a tester on it. Am i missing something easy here? Some secret portal through the wheel well or something?
-There is a butt connector in the conductor energizing the start solenoid however and with the key in the crank position I have 24V there.

Sorry for the long post.....
Any help you can give me would be great. Were forcasted for ice/snow thursday so I dont have much time to sort it out.

Thanks for all your knowledge guys and sharing it on this site....

 

[MarcusOReallyus]

Hi, BB. Welcome to the site!

-There is a butt connector in the conductor energizing the start solenoid however and with the key in the crank position I have 24V there.
.

Measured with a meter or test light? And what was the test point? Before or after the butt connector. I'm just wondering about corrosion providing a high resistance that would allow a good reading with a meter, but not actually pass enough current to crank the starter. That clicking you describe could be a symptom of that kind of thing.

 

[boatbuilder]

Thanks for the quick reply! All measurements were done with a meter. The test point was outgoing from the but connector. It had shrink tube on it that I cut off to access it (very hard to get at) and looks to be in ok shape. I am very familiar with the issue you are describing but dont believe this particular connection would be the culprit.
The fast irregular clicking has occurred for a while on and off, and even happens after the truck is started come to think of it, while its warming up so may be unrelated to the starting issue...?

 

[MarcusOReallyus]

Thanks for the quick reply! All measurements were done with a meter. The test point was outgoing from the but connector. It had shrink tube on it that I cut off to access it (very hard to get at) and looks to be in ok shape. I am very familiar with the issue you are describing but dont believe this particular connection would be the culprit.

Yeah, sounds like it's not. Okay, good you are on board with that. It trips a bunch of people. Drove me nuts first time I ran into it as a young tech many moons ago. The theory is all there, but recognizing it in the field is another matter.

The fast irregular clicking has occurred for a while on and off, and even happens after the truck is started come to think of it, while its warming up so may be unrelated to the starting issue...?

Yeah, might even be the GP relay....


I haven't had trouble with my starter circuit to this point, so I don't have much experience with it. Let's hope some of the wiser heads can chime in here.

 

[ken]

There is a small silver relay under the dash mounted right by where the radio would be in a civi truck. It is rectangle shaped about 1/2 wide and about 1 inch long. It is how the starter is operated from 12 to 24 volts. I assume you still have it because you mentioned no doghead mod. This relay is a known fallure point. They are not very robust and normally fail closed making the starter run until you disconnect the battery. I have had them fail in the open position. If this has failed, you can get another one from a civi truck. It is also used for the AC fan blower motor relay on civi trucks. It is mounted by the fan blower motor under the hood on civi trucks. I recommend not replacing it and going the doghead route. It will fail again. If this is not your problem. You will need to pull the starter and have it tested.

 

[boatbuilder]

Thanks for the reply Ken. Do you happen to know the napa number or stock part number for those relays? Also any tips at getting at the starter to drop it, Ive read the horror stories about bolts and shims, really anything that comes to mind that might make it quicker or easier for me would be greatly appreciated. Is it worth jaking/blocking the passenger side up? Maybe I'm overthinking it but I'm working outside and it'll be about 20 deg thisafternoon when I get off work.
Thanks for your time

 

[doghead]

Rapid clicking of the glowplug relay is an indication of failed glow plugs(the system is designed to do this).

Test all 8 glow plugs.

As for your starter, it sounds like you need to drop and test it.

 

[Gramps]

If I'm correct its AC-Delco 15-81743. Although alldata isn't being to helpful with part explosions.

 

[royalflush55]

From the CUCV WIKI FAQ: GM 15591718
NAPA AR135
Carquest RY117
Autozone AC40 Has extra pin but works and are made in USA still.

 

[319cssb]

First you clean all ground connections and put dielectric grease on all contact surfaces.
Then you test and charge both batteries .
Then you test the ignition solenoid or better replace it with a different model from napa.
Then you test the ignition switch , replace if necessary.
Disconnect the batteries and remove the starter. Bench test it. Using a multimeter test both starter hot and ignition wire for continuity.
This should show the fault somewhere.


remove glow plug card and clean contacts, visually inspect it. Use dielectric grease on contacts.
test and replace glow plugs as needed. Test resistor pack.

 

[Tinstar]

If starter hasn’t been rebuilt in a while or never, I would recommend having it rebuilt.
It’s already off the truck if you’re testing it.

Don’t forget to use new starter bolts and that the front bracket is installed.

 

[boatbuilder]

Thanks everyone. Got it running again tonight. I picked up a replacement relay on the way home and had the same problem after installing it. So next step was to drop the starter which was less of a pain in the butt than I expected. After getting it to a place where i could put wrenches on the electrical terminals I realized the solenoid wire was not attached. Had a good terminal on the end but literally the nut had come off the stud, and wire was not connected! I figured i had it off that far so pulled it out and bench tested it, reinstalled and started right up.
Thanks for the input guys, I appreciate it.