6.2l glow plugs

4320diesel · Feb 11, 2009

on my 85' gmc 1500 4X4 truck with the 6.2l diesel in it the glow plug light only comes on sometimes when the engine is cold is this the plug controller screwing up or what and the right rear brake light/turn signal doesnt work the bulb is fine there is no power comeing to it does anybody know if there is a comon break for these? and the hi beam lights on the dash dont come one but i assume its the bulb any help is apreciated

Kentb of SWMO · Feb 11, 2009

Do not know on the glow plugs, but on the brake light/ turn signal, check the wiring harness to the rear of the truck. Some would come out of there mount and rub/burn against an exhaust pipe. If that is OK, most likely a bad turn signal switch.

Kent

bradk · Feb 11, 2009

Glow plug controllers are pretty common failures on the 6.2"s. Alot of guys around here have installed a push button to eliminate the controller,but keep in mind,you can burn the plugs out by energizing too long.

As far as the lamp,start by unplugging the rear tail harness at different connectors at the frame starting at the front and check with a test lamp to narrow down where power is lost.Should be the yellow wire.

JDemaris · Feb 11, 2009

You might just have a bad inhibitor switch. You can buy a new one for $15, or simply just bypass it. It's there to stop the glow plugs from working once the engine is warm. Got used in all 6.2s up to around 1990. Screws into a coolant passage and has two prongs. Actual location can be one of three different places depending on year, and C-code 1/2 ton or J-code 3/4 and 1 ton versions.

JDemaris · Feb 11, 2009

I've found controller failure to be rare in the 6.2s - although controllers are often wrongly blamed for problems. I've got over 20 6.2 trucks, Blazers and Suburbans and have never had a single controller that needed replacement.

Anonymous-0 · Feb 11, 2009

Brad,

He did say the right rear,stop/signal so didn't you mean to say the green wire?

~Will

4320diesel · Feb 11, 2009

thanks i figured the problem out the plugs didnt come one because i never pushed the throttle down a bit so the cold rev solonoid wasnt all the way open so the glow plugs didnt come on as soon as you touch the throttle the light comes on and the brake light wire was broke right before the weather proof conector in the middle of the rear bumper thanks for all teh replys

Jon Hagen · Feb 11, 2009

JD, Your very lucky if you own that many 6.2-6.5 engines and never had a glow plug controller fail. I have had to replace several erratic or non working control modules. The problem is a poor design where the module electrical plug is not supported by the plastic socket, it is supported only by the electrical blades attached to the PC board.
The weight of that plug and blades, when subjected to the vibration of those diesel engines, will vibrate those blades loose from the PC board and lose contact.
Wedging a wood or cardboard shim between the plug and controller housing adds enough support to much reduce vibration of those connector blades and improves the life of the units.

JDemaris · Feb 11, 2009

Cold advance solenoid on the injection pump has nothing to do with the glow-plug circuit except they both only work below certain temps.

4320diesel · Feb 11, 2009

oh but when ever i tap the acelerator the glow plugs kick in so it has somethin to do with that

Bob · Feb 12, 2009

WOW!

You certainly have NO idea about the GP/IP/cold start system on your truck!

4320diesel · Feb 12, 2009

i dont know why it does it but it does as soon as you tap the pedal the glow plugs kick in right away

6.2l glow plugs

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