Intermittent wait light problem (stays on a long time and won't start)

[n8roro]

Most times the wait light and glow plugs work flawlessly. A couple of times this week the wait light stayed on over a minute and when I turned the key the engine did not start. I tried a again and it took about a minute for the light to go off and the engine still would not turn over. Third time it glowed for less than 10 seconds and started fine. The weather has been in the 70's and 80's, and it went pretty much the same way on both occasions.

I tested the batteries today and they are 12.6 and 12.7 V. There is a little corrosion on the positive of the front battery which I will remove tomorrow.

I did the Doghead relay mod last year, and the glow plugs were all replaced with 60G's as well.

Is this a glow plug card issue?

Any help is appreciated with troubleshooting ideas.

Can I check for voltage at the plugs by going from the negative front battery terminal to the glow plug lead, and is 12V what I'm looking for there?

Does the glow plug wait light go off based on engine temperature?

Thanks,

Nate

 

[cucvrus]

First off starter relay changed will NOT be associated with glow plugs. I would take a test light to the glow plug relay on the fire wall under the hood at the master cylinder. You should have power going to the top stud. The 3/8" stud. In my case 24 volt coming from the ballast on the firewall. Next with the key on engine cold that power should be tranfered thru the relay and the bottom stud should be hot and light the test light. If not the interior contact in the relay has become dirty or slag ridden. That would be my first check. It happens. Please report back. Doing all these off the wall modifacations that are recoomended just compound the diagnosis. But do as you wish. Have a Great Day and enjoy the Holiday weekend. Hopefully the CUCV is not your daily driver. Take Care.

 

[n8roro]

You nailed it! The relay did not light the test light from the bottom stud. Thanks for the advise . Is that a part that can be removed and cleaned, or should it just be replaced?

I see your point regarding the modifications. I bought this truck to learn basic auto mechanics, and I'm doing the best I can while figuring it out as I go. Between this forum and the TMs there is a wealth of information to learn from. I did save all the old parts though so I can go back to stock of needed down the road.

 

[n8roro]

Mine is from '91.

 

[MarcusOReallyus]

.... I tried a again and it took about a minute for the light to go off and the engine still would not turn over.

Would not turn over? Or would not start? Those two terms mean different things. Turn over means just that - the starter motor did its thing and the engine went roundy round. Whether it started or not is another question.

You nailed it! The relay did not light the test light from the bottom stud. Thanks for the advise . Is that a part that can be removed and cleaned, or should it just be replaced?

Replaced. NAPA part ST-85. Or similar. You need FOUR terminals, it must NOT be grounded through the case.

I see your point regarding the modifications. I bought this truck to learn basic auto mechanics, and I'm doing the best I can while figuring it out as I go. Between this forum and the TMs there is a wealth of information to learn from. I did save all the old parts though so I can go back to stock of needed down the road.

Don't form opinions on mods too quickly. Some, like Rick (cucvrus), are dead set against any and all modifications. Some are gung-ho for modifications. Go slow, make up your own mind. By the way, Rick has forgotten more about the CUCVs than most of us will ever know, so don't think I'm putting him down. Quite the contrary! He knows his stuff, inside out and backwards. He's also a great guy. But to modify, or not modify, is a personal decision and there are a lot of factors to consider.

 

[cucvrus]

http://www.murcal.com/trombetta/trombetta_contactor_metal.html

This company here has the best glow plug relays on the planet. I received this contact from antennaclimber. I do not have the part number at my finger tips at the moment. Maybe the Myth. The Legend. Mr Glow plug card can assist with the correct part number for the CUCV in stock form. Please Sir. Thank you. Have a Great Day. You can also buy the rubber boots from this company for the relay and I have used them on the alternator hot studs also. Good Luck

 

[MarcusOReallyus]

That thing looks pretty good, Rick. Same physical layout, so completely interchangeable, but the specs are a definite upgrade from the ST85.

 

[n8roro]

Just got back in town from a long weekend, so sorry for the slow reply.

Would not turn over? Or would not start? Those two terms mean different things. Turn over means just that - the starter motor did its thing and the engine went roundy round. Whether it started or not is another question.

It would not start. The starter worked fine and the engine was cranking.
Thanks for the part number and advice!

 

[n8roro]

I found a: ST85 Continuous Duty Solenoid Starter Switch FOR 12 Volt Systems 80 amp (Made in Mexico) on ebay for $20 with free shipping so I ordered that. Is there a way to test it with a multimeter before installing it to be sure its good and correct, or is that not needed?

 

[MarcusOReallyus]

Hmmm. 80 amps is what the circuit draws, so you'll be running it at its limit. That will shorten its life compared to one that's rated for 100 amps. It should work, though.

To test it, use the continuity test across the two small terminals. There should be continuity from one small terminal to the other, and NOT to the case.
You can also test the two large terminals. There should be NO continuity from either large terminal to anywhere else.

IF ANY TERMINAL SHOWS CONTINUITY TO THE CASE DO NOT USE THAT RELAY.

Once it's in place and all hooked up, assuming you have a stock system, here's what you should see:

LARGE TERMINALS:
24v at the top terminal (power from batteries), when the GPs are NOT activated. (If you have done the resistor bypass mod you'll see 12v.)
12v at the top terminal (power from batteries), when the GPs ARE activated.

0v at the bottom terminal (to the GPs) when the GPs are NOT activated.
12v at the bottom terminal (to the GPs), when the GPs ARE activated. (actually, could be a bit less with an old relay.)


SMALL TERMINALS:

0v at BOTH terminals when the the key is NOT on.
12v at the top terminal (orange/black wire) when the key is ON.
12v at the bottom terminal (pale blue wire) when the GPs are NOT activated and the key is ON.
0v at the bottom terminal (pale blue wire) when the GPs ARE activated and the key is ON.



Oh, by the way, "top" and "bottom" aren't really important. Those terms just describe the factory mounting. Functionally, it doesn't matter. One large terminal gets power from the batteries, and the other sends it to the GPs. One small terminal gets power from the key, the other goes to the GP controller card. Swapping them is no big deal. Just keep SMALL and LARGE separate.


Let us know how it goes!

 

[n8roro]

Fantastic, thank you!

The Napa ST-85 has the same specs as the one from Ebay so I thought it would be ok.

I'll try to cancel that order and order this instead:

Trombetta 974-1215-011-09

(There is also Trombetta 974-1215-010-09 which is the standard and does not have dust and liquid seal)

 

[n8roro]

Success!



It started right up. Thank you for the help.

 

[MarcusOReallyus]

 

[Mad Texan]

The M1010 didn't start yesterday... but was huffing gray smoke while cranking. Well, it's not fuel. I noted that the glow plug light seemed to be acting strange when I was waiting for it. A quick search and I found this thread. I got to thinking that I bought a relay and never put it in. I didn't bother with the voltmeter and installed the relay I had. Fired right up! Thanks! I will be putting another one in the spares bin.

By the way the date on mine was 03/08/90...

 

[BradL84D30M1008]

Fantastic, thank you!

The Napa ST-85 has the same specs as the one from Ebay so I thought it would be ok.

I'll try to cancel that order and order this instead:

Trombetta 974-1215-011-09

(There is also Trombetta 974-1215-010-09 which is the standard and does not have dust and liquid seal)

Where did you order yours? I'm thinking I'll order a spare......

 

[n8roro]

I am having a similar issue again and went and found this thread after having a deja vu feeling! I bought this one when I had this issue in 2019:

Trombetta Metal - 12VDC Contactor (974-1215-011-09

It has a 2018 manufacture date on it but has no power to the glow plugs with the key on. I started another thread about my current issues this evening because I forgot I made this one, so if it's better to combine them, please do.

Its almost 4 years later to the month and the same issue is back. I ordered another solenoid that should get here Monday and hopefully that solves the issue.