Firstfives.org

Howdy,

When I pulled my instrument cluster out of my 520, there were red and brown wires going to the back of my clock.

However, on that same harness were three other wires, connected to nothing. Could those be for a tachometer?

Can't seem to find a drawing that applies on realoem.com

TIA,
Craig

Yes, these three wires could be for a tachometer. Usually the harness is the same - for cars with clocks or for cars with tachometers. If these three wires are:
1. Green/white wire for +12 V (terminal 15)
2. Brown wire for GND (terminal 31)
3. Black wire from the ECU or from the coil, negative (terminal 1)

Before that you have to check the tachometer - it could be for 4 or 6 cylinder engine (M10B20 or M20B20). This is stamped on the back metal cover of the tachometer. You can use only this tachometer, which is suitable for your engine.

Thanks you for the detailed reply.

Much appreciated!

Craig