problems after m42 swap, help please!

[baggimodo]

After I've swapped in an m42 I've now not got any temp reading or rev counter. I didn't realise about the positive to earth problem and it melted the wiring in the loom.

I've tested the wiring to the temp gauge by earthing it and I get movement on the guage so don't suspect terminal damage here but could I have damaged the rev counter wiring? Does anyone know which wire feeds information to the rev Counter from the en
gine bay? And the corresponding wire to look for ecu side?

[Speedtouch]

It would help to know what model of car you have converted from!

There are wiring diagrams here:
http://www.e30zone.net/e30zonewiki/inde ... g_Diagrams

[baggimodo]

Oops! 318I m40 sorry!

[Brianmoooore]

What did the M42 come from?

[baggimodo]

E30 off zimmer Matt

[Speedtouch]

If earthing the temp gauge gets it to move (it should fully deflect), then it should work OK with the sender; if not, measure the resistance of the sender with the engine cold then hot, to verify that the sender is working.

Melted wiring looms can damage any part of it, so you need to carefully check each of the affected wires, and trace them back to where they go - use a multimeter to check their continuity.

[Brianmoooore]

E30 off zimmer Matt

That's my theory gone then! BMW engines from other models can have a sensor that's incompatible with the E30 gauge, so need to be fitted with an E30 sensor.
Follow what Speedtouch says for the temp gauge.
Tacho wire is a plain black one from a dedicated output on the ECU to the instrument cluster, passing through the C101 on the way.