Glow plug relay issue
 

1983 GMC 3500 6.2 Glow Plug issue.Key on, faded glow plug light, Changed relay. Old relay quit clicking. New Relay doesn't click either. The pink wire to relay is good and powers up with key on. Blue wire from relay to controller has no power. When key is turned to start (Ignition) absolutely nothing happens.

Also, when foot is off clutch voltmeter registers at 9 volts. When clutch is pressed Voltmeter goes up to 13 Volts.


Any Diesel guys out there??? I would greatly appreciate any help, please.

Re: Glow plug relay issue
 

Might check out the CUCV section of the Steelsoldiers website. The Sticky:CUCV helpful threads have the military TMs plus several troubleshooting guides. The CUCVs are basically square K30s with a 6.2 and a partial 24V system. Most of the troubleshooting guides work for the civilian versions of the truck.

Re: Glow plug relay issue
 

The relay controller grounds the blue wire. So take a jumper wire with the key on and ground the blue, relay should activate. The controllers are junk along with the heat sensor. Eliminate all of that. Splice into the blue wire and run it inside to a grounded push button. When the engine is cold just hold the button down for no longer than 5-6 seconds at a time with a 'rest' in between so you don't blow the tip of the glow plug

Re: Glow plug relay issue
 

Good morning. The original relay was clicking and in the start mode of the key the engine was cranking. The relay had stopped clicking. So, I figured that is had faulted. I purchased a new one, installed it. The new one does not click (cycle). The key in the start position does not engage the starter. I push in the clutch, I have full power (volts). I release clutch, I have 8-9 volts. I only have one battery hooked up. I read somewhere that I need both batteries. The blue wire has no power. I just recently purchased this truck. It has been sitting for about 3 years.
It seems as though that I might have several issues that are occurring.

Re: Glow plug relay issue
 

The contactor is usually not the problem. The thermostatic timer module in the intake manifold is usually the issue. GM used these from 1978-1984 on the 4.3L, 5.7L & 6.2L diesels. They were not the most reliable piece of equipment when they were made in this country and the new Chinese versions are just plain not worth buying.
The electrical connector and the controller were both at fault.

I would upgrade to the all-in-one contactor and timer controller that GM used from 1985 til they stopped making the 6.5L in the early 2000's.
I'd also update the old Delco 9G or 11G glowplugs to the Delco 60G Positive Temperature Coefficient glow plugs. Digging the broken ends of the swoolen 9G or 11G glows out of the heads is a miserable job even after you remove the fuel injectors.

The 1983 wiring diagrams have a pretty decent wiring layout of the old thermostatic timer controller.

Download the 1989 RV wiring diagrams for an easy to follow later glowplug wiring diagram.
A shutoff sensor on the head will work as a glow inhibit sensor on the 1985 & later controller or just let the glows run on every startup.
The Metripak connector part number is in the wiring diagram. You can probably get a pigtail if you don't have the tooling to build a plug.

Re: Glow plug relay issue
 

You will not have power to the blue wire----it is a GROUND wire. also sounds like you may have a fusible link out down by the starter