Good Morning Forum,
I have a gray market, 1980 W123 300D. The glow plug light does not come on when attempting to start the car, therefore the relay is not doing its job. I have now replaced the relay and the glow plugs.

Backstory: We went on vacation in the W123 from Louisiana to California. Got there no issues, on the return trip in Elko Nevada in the morning after spending the night we went to start the car for the days journey and the wait to start light did not come on, thought hmmm is the light bulb out?, nope it would not start, crank yes but not start. Had her towed to a diesel mechanic in Elko, who was all about diesels and actually owned a car older Mercedes than mine. He diagnosed it as the relay was out and to buy a battery cable to jump the car to get her home. We did not turn the car off that day. Spent the night in Cheyenne Wyoming and jumped it with the cable to start it, all good. We did turn the car off that day but once she was running she started not problem. We get home put her back in the garage and went buy parts. Spoke to my son, SirNik84, and he suggested to change the glow plugs too as he had not changed them when he rebuilt the car. Ordered a new relay, just like the one she had, got the new glow plugs and now back to yesterday.

Change the relay and glow plugs and still no wait to start light and the car is not doing the glow plug cycle. She still cranks so battery is good, it was new with the rebuild. Thoughts of things to check......
I am going to look at the fuses today but I am up for suggestions for thing to look at or test.

Thanks for your help,

Nik's Mom (Peggy)

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80 300D
84 300CD
82 300D - t-boned 4 Nov 2013
01 Jeep Wrangler
09 Smart