No glow plug light at times

[87TurboT]

I was working on the wipers and had the key on to adjust the linkage. When I went to start the truck no glow plug light. The next am light came on and started fine. Came home from work today, went to start about 45 mins after being home. No light. Waited another hour, still no light.

[bobt]

Based on my experience with my '93, likely problem is the glow plug controller. In my case, after about 45 min to 1 hour, no glow and no start. Less than 45 min, had enough residual heat to start. Wait awhile longer, hour and half, and would get glow and start. Replaced the controller and problem fixed.
Bob

[JohnC]

The '93 originally had a glow plug inhibit switch. If the water jacket temperature is above a certain temp, no glow plugs. Replacement "switches" are just a jumper, so glow plugs work all the time.

[trbankii]

Hmmm, so I can just connect the wires going to the switch? Where is the switch located?

I replaced the relay when I first bought the truck, but there are times I don't get the glow cycle and starting is harder.