wait light

[2deuce]

I'm trying to understand this system better. I read through the TM. I have a truck with the resistor bypassed. It would seem that bypassing the big resistor would be a good idea, but thats another thread. What turns the wait light off? It wants to stay on with the truck running. If the module turns it off, where does it get its info? Being the resistor is bypassed I think the troubleshooting guide won't always apply. The wait light won't come on with the module removed. I put in a different module with the same result, the light stays on. The TM says not to leave the key in the on position over 2 minutes, so I was concerned that leaving it running may damage the glow plugs. I put a meter on a plug and it reads 12 volts, with the key on and the wait light on. Not waiting until the light goes out start the truck. A steady 12v continues to be supplied to the glow plugs for 30-40 seconds after the truck starts with the wait light still on. After that the power drops to zero at the glow plugs and the wait light goes out about 10 seconds after that. Any ideas what is causing this. Does it have to do with the resistor being bypassed? Thanks

 

[1986Blazerk5]

Maybe its the relay not turning off how old is your relay?

 

[wallew]

There are two (three?) relays under the dash. Once I changed both of mine, several minor issues were resolved. They are not expensive being less than ten buck at the auto store I went to.

There is one attached to the wiring of the circuit of the gp module. But hey, if you are going to replace one, replace both. Might be the exact fix you are looking for. And even if it's NOT? You can cross relays OFF the list of possible problems.

 

[2deuce]

I forgot to mention that I replaced the glowplug relay and nothing changed. I'll look up under the dash for those other relays. Thanks

 

[1986Blazerk5]

do your glow plugs turn off, or are they always on

 

[2deuce]

The glow plugs don't cycle, they come on when the wait light comes on, the truck starts after I give the glow plugs 10 seconds, the plugs stay on another 30 seconds, then shut off. About 10 seconds after the glow plugs turn off, the wait light then goes out. I had my meter on a glow plug and had my daughter start the truck and watch the wait light. I tried 2 different glow plug relays one was new and 2 modules. I only timed one of the modules but they acted the same, so I don't think its the module or GPR.

 

[itsunday25]

the glow plugs will stay on after the truck starts up and till it get warm and they go out the light staying on could be you card.

 

[2deuce]

what signal does the module receive to turn the power off to the plugs. I know it gets a signal from the temp sensor whether or not to send power to the plugs, it could be the temp sensor I guess, because when the truck is warm but not yet at operating temp you can get a variable wait light depending how warm the engine is, I might try changing that next

 

[2deuce]

I'm calling the card a module, 2 of them acted the same way. I'm going to look into the temp sensor next.

 

[itsunday25]

the cucv glow plug sestem was the week point in the trucks put a push buton 4 the glow plugs much better that way.