94 K1500, Glow plugs not operating.

[GM Guy]

Hey all,

My buddy with the 94 K1500 messaged me telling me the glow plugs wont come on when he turns the key, and consequently it won't start. (he isn't very mechanically inclined, doesnt know that pliers across the studs would work. )

Basically I guess after I replaced his OPS and PMD, it started and ran fine for a while, and then one day the glows wouldnt come on.

Before I drive 40-50 miles, I wanted to brainstorm with you guys on what it could be.


Is the fuel heater on the same circuit on 94 and older like it is on 95+?

Would a bad CTS for the ECM (the one in the coolant crossover) cause no GP operation? I know i touched it when I was routing the new PMD cable, but I dont think it was ever bumped. It did look like it could be original.

 

[WarWagon]

CTS, yes. Thinks the engine is hot and disables the glows. He have a SES and STS light on key on? Codes?

 

[Burning oil]

Does he get 12v to GP side of relay?
_____________________________ Yes = bad GPs, fusable links or wires.
_____________________________ No = bad relay or control signal.

A WTS light on dash means 12v is making it to GP side of relay.

 

[JMJNet]

Fuse?

 

[jrsavoie]

I had to replace the ignition switch on all of my vehicles - except the 1994's to cure this.

I never had this issue on a 1994 but if it happened on all my others, it might be able to happen on a 1994.

I have started replacing the engine harnesses on all of my vehicles as I work on them. Glagulator on dieselplace makes new harnesses. He is the only place I've been able to find a direct replacement.

I started running the harnesses on the right side top of the manifold, instead of underneath - easier to get to.

On a 94, I would also advise him to do the dual lift pump relay upgrade or buy Leroy's kit

 

[GM Guy]

Can the relays stick?

Took the test light, one stud hot like normal, turn the key, no WTS, no juice at the fuse under the dash, etc.

Turn off key, clip remote start button (Lisle test tool, replaces pliers shorting across. ) onto terminals, hit it, release, turn key on, glows cycle normally, WTS light and all. Fires right up!

Unfortunately he is trying to sell the truck, so no upgraded LP harness.

 

[jrsavoie]

Relays do go bad

 

[WarWagon]

The 1994's are just "dumb" relays. You can probe all the connectors on the GP connector and see if you get a signal from the ECM to turn it on. If so then the GP controller (relay) is shot.

List the rig on here for sale!

 

[Will L.]

Dude! A obd1 half ton 4x4 needs to be listed here. Somebody will need that truck. And most everyone here is not afraid of knowing that repair is needed.

 

[GM Guy]

even with rust and a ton of miles and blowby?

If there is still interest, I can try to get some pics of it and a price.

 

[handcannon]

I'm not dealing with rust, but blowby? Blowby can be dealt with if the price of the pickup is right. My pickup was a rebuilder due to front end body damage, but it didn't have blowby when I got it. Before I started tearing down my pickup I've had people along side me at stoplights ask me if I was overheating. Even had one person concerned that I might be on fire. But, surprisingly it still seemed to run good. I'm even more amazed now that I've seen what the interior of the motor looked like.

Don

 

[WarWagon]

If all else the vultures on here could pick it's carcass clean...

I always wondered how much longer my engine with on fire blowby would have run with copper showing in the bearings? That, having a spare engine all of a sudden, and the pissing oil out the front seal was the reason I pulled it out. Didn't want to find out in the middle of nowhere. My project truck wouldn't start and had worse blowby.