My glow plug light comes on 75% of the time. Two years ago my mechanic ran a jumper that made the relay turn on by a small button under my dash. I don't need it very often... so have never replaced it. Car starts perfect...even after sitting for a week and temp. 10 F. I think he hooked the wires to the circuit that warms the engine after it has started...fooling the relay into thinking the engine is running. This way, when it is real cold outside I can run the glow plugs after the light turns off...to make sure it starts smooth...and keep the switch pushed until engine is smooth. I do this is because the CAT loaders I operated had manual glow plugs, with a timing chart for the temps & mintues to heat the glow plugs... pasted on the dash CAT told you you to heat the engine after it started until "did not run rough". I operated equipment for over 20 years...with very breakdowns.

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