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This is an issue from when the original wiring harness was assembled.

There are several wires that come up between the second and third runners for the intake manifold, I can't remember exactly which harness it is, but in one of these is a ground wire that is pressed together, and this is a cold joint that is causing your issue.

So, locate the one for the ground wire, and if your black plastic sheathing is still in place, just feel down the plastic for a bulge, and this is where the cold joint is located. Then, cut the plastic about two inches to the left of the bulge, then you can slide the sheath off, after you disconnect the ground wire.

You will need to get this pressed connection real hot and resolder it. I used a small butane torch when I did mine about 15 years ago, and I have not gotten a coolant temperature sending unit fault code since.




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If it needs to be maintained, repaired or replaced on a 1990 240, I've probably done it. '90 240DL, 292K looking forward to 300K badge (or sticker??). >>You haven't really worked on a car until you draw blood<< :-}