Question about GMC truck
 

Hello,
I have a 1985 GMC pick-up that I would like to know where the glowplug switch is located.I think it is staying on to long even when the engine is warm.
Thank you

What is going on is called after glow It is supposed to do this although you may way to consider replacing the TSU Temperature sending Unit as that is what tells the GPs to come on and off AC/DELCO only take my and anyone else that knows anything about 6.2s/6.5s BWD and that GP sorensen is no good for these trucks But I belive that the TSU is the culprit

The temp switch for glow plug activation should be located on the back of the passenger side cylinder head for that year truck.

I don't think the glows are supposed to activate above 135F or so on that era truck but forget the exact details?

Thanks for your responces .Is the temp switch anything like the sending unit for the water temp?

No not exactly-there are 2 terminals and it is flush mounted to the back of the head.

GMC 6.2 glow plug issue
 

Thanks for your reply.Is there anyway to wire a manual switch to manualy operate glow plugs on & off with toggle switch under dash for example? Thanks

Sure
Get a continuous run snow plow solenoid and a momentary switch and appropriate wiring and use the snow plow solenoid to jump the stock relay.

The solenoid must be capable of handling more than 120 amps.

Be aware that some snow plow solenoids activate with power and others activate with ground-wire accordingly.

GMC 6.2 diesel
 

Thanks,I'll run that by my son.He is in the electrical rebuilding business and has these things in stock.I think he will be able to do the job.We will see.Thank you again,I'll be in touch.