New to me 300CD. It came to me w/o a working tach. The pink label ECU was in the car when I got it (not the one in the picture). I've tried 2 other used pink label ECUs and neither make the tach work. Today I tried the off white one and still no tach.

The tach will work if I jump the wires on the ECU plug.

Both the pink and off white ECUs are reported to be for a 1985 300D/CD/TD. I can't find any info on the internet that tells me the difference between the two.

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1985 300CD, CA
172 Anthrazitgrau/Palomino 154

1985 300TD, CA
040 Schwarz/Palomino 154/3rd row seat

1985 300TD, CA
473 Champagner/Palomino 154/Cargo cover