please check GP thinking 85 300sd
 

Yesterday I lost my Glow Plug light.
Seems to start and run fine, but checking the system anyway, the light never stays on long.

Following the diesel giant guide, and what I could find here, I have verified proper power into and out of the relay.

Pulled 1 GP and it measures 0.5 ohm.
BUT the wire reads 190 ohms to all GP with them installed in the car. Did not read the wire where I removed the GP. I will go do that.

So, is the bulb out, or as I am suspecting, the wire harness is bad. What am I missing here.

thanks
Doug

Have you checked the resistance values of any of the other glow plugs other than #1? I would try that, and also check to make sure that you have 12 volts at each glow plug when you first turn on the key.

Found 1 bad GP(#1). How will that affect the system? Also the #5 GP was not connected? but was good.
Now that I have them out should I cange all of them? And on the wires near the ring terminal there is exposed wire, just where the insulation has broken. Can that just be taped up with electrical tape?
All wires ohm out good.

Where does this system get it temp reading from? The resistance of the GP?

Thanks
Doug

As far as I can remember the light acts funny if one plug is bad and stops working if two or mor are bad on the 5 cyl engines. You should replace the bad one and hook up the one that was not connected. As for the bare wire use something to make sure that the wire does not short to the block.

Also, check your wires when disconnected from the GP. You should have next to zero resistance from the wires themselves.