Custom tach, which pin #?

[christod]

Hello everyone,
I've put a custom tach (VDO vision series, black face, dont worry :) in my e21 w/ m42. Does anyone know where I can find a guide to the ECU pin #'s?

Cheers!
Chris

[Vladi]

The thin black wire is the signal for the tach.

[christod]

Thanks Vladi :)

[xsjado]

ive lost all hope to put back the m40 tach to m42 ecu back so now i just rely on the shift light....

[christod]

Hmm, I'll keep puzzling over it, Ill post if I can get it to work

[john318isau]

You can get a rpm signal from the instrument cluster connector. You may need to install a resistor though. "Connect the engine speed input to pin 7 of C1, the connector on the back of the instrument cluster closest to the tachometer."... from http://www.motortraders.net/groups/group.asp?group=1&menu=1&article=15