You start at the glow plug relay. Take off the cover and you will see a big plug and a small. The big plug is numbered 1-6. This is the number of the glow plug is goes to starting from the front of the engine.

I test by applying power to each pin for 10 seconds while reading the amperage. IF the amperage is above 15, you are oK on that plug.

Good luck

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Benzmac:
Donnie Drummonds
300E
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM