Glow Plug Light

[EscaladeDiesel]

The glow plug light will illuminate slightly then go off, then repeat this pattern while driving my 1983 Suburban. Any ideas? THANKS

[NH2112]

Does it still have the original glow controller? Current from the alternator is used to heat an element inside the glow controller, and the element opens a thermal switch that kills power to the glow plug relay. If the element is failing intermittently the switch will close and the glow plug relay will be energized. I suppose fluctuations in the alternator's output could have the same effect as well, along with high resistance in the wire from the alternator to the element (the brown wire, I believe.) Personally, I wouldn't worry about it unless the lamp begins staying on for longer periods with the engine running. They're wired in parallel so if both the light and the plugs work on cold starts then they'll both work when hot as well.

According to the troubleshooting guide, engine coolant temp also acts on the thermal switch, so if you're running a little cool it may fire the plugs.

[EscaladeDiesel]

Hey Phil, It probably is the original controller. I have had the truck 6 years and haven't changed it during that time. The engine runs warm at the very least, NEVER cool, it has the fastest warm up I have ever had on nearly any vehicle.