Tacho dead after engine change

[matt320]

Hi all,

I was wondering if anyone had any suggestions why a tacho shouldn't work after changing an engine. I went from an 87 jetronic to 89 motronic. Same 2.0L M20 engine, put in new loom and ecu etc. I have tried changing clusters and this doesn't help.

Thanks for any help.

Matt

[A1BMW325iSport]

Hi, find the 3pin plug by the ECU, the black wire is the tacho feed, connect a length of wire onto it, and run the wire up to the instrument cluster, connnet it to the black wire (pin7) on the BLUE PLUG and you will have your tacho back.

[matt320]

Cheers A1, i will give that a go at the first opportunity.

Matt

[Brianmoooore]

Tacho didn't work on my Touring after I put the M50 in. Turned out to be The C101 plug/socket not connecting properly.

[ian332isport]

The problem here is that you have fitted a facelift engine in an early car.

On the early cars, the tacho (and fuel rate) signals did not pass through the C101 connector. They went a different route which is the three pin connector being mentioned above.

Your new engine does have these signals passing through the C101, but you don't have the matching wires on the car side of the connector.

You need to find pin 8 (white/black) and pin 9 (black) in the engine side of the C101 connector, and connect these to the 3 pin connector (C104) under the dash. You need to connect pin 8 to pin 3, and pin 9 to pin 1.

Cheers,

Ian.