Going to install a small tachometer in our ‘89 245DL wagon in one of the places beside the radio. Everything so far looks fine, BUT can anyone tell me exactly where does the wire go FROM the small light that is already in the tach to the power source for the light?

So far just cant yet see where that wire goes for the power for light.-? Thanks.

Volvodad has the right information.

I installed my small tach a few months ago, and did this exactly.

Don't forget that you also need to power your tach. Fortunately, I was able to grab the wiring harness for mine at the junk yard when I found a 245 with the small tach in it. It has a spade connector on it, and I ran mine over to the fuse pannel, and connected it to fuse number 14 or 15.

Good luck with your project.
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If it needs to be maintained, repaired or replaced on a 1990 240, I've probably done it. '90 240DL, 321,450 miles, will she make it to 400K ?? >>You haven't really worked on a car until you draw blood<< :-}

You can pull the centre console slightly rearward by undoing the two screws at either side and the small ones below the lower storage hole ahead of the gear lever, and access the Brown wires that feed the lights above the heater and A/C controls.

Splice the tach light wire (Scotchlock connector) into a Brown wire and run a ground from the tach to one of the large screws that bolt together the metal framing behind the console. These will already have a cluster of Black ground wires attached.
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Bob: son's XC70, dtr's '94-940, my 81GL, 83-DL, 89-745(V8) and 98-S90. Also 77-MGB and some old motorcycles.