Trying this on this forum since more active. My 1994 S350 Turbo Diesel has been doing fine until the other day I got in the car and went to turn the key on to glow it, the glow plug light came on and right away went off very quick much quicker than normal. Tried to start it and it just turns over and over never fired up. I repeated the glow plug light and it continued to just light up and right away go back off. Tried car again the next day and the glow plug light worked correctly, did fine for a coupld days and now it is back again and I haven't been able to start it for 3 days now. The car has had a new wiring harness and glow plug relay in the last year so those should be out of the question. There is a clicking sound that comes from the engine that is related to the glow plug light, the click happens everytime you activate the glow plug light and I had a buddy turn the ignition for me and I traced it down to the base module. Does part of the base module control glow plug function on this car? It has three fuses in the top of it and I checked them and all tested good.

You might have a shorted glow plug, the timer relay has a self resetting circuit breaker built in.

Although I am making the assumption that your 350 controls its glow plugs like my 350...

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.