Tach wire

[1badplr]

I picked up a Stewart Warner Tach light at the charity pull last night. Does anyone know where the tach wire is? What color, any help would be greatful. Thanks.

 

[rbattelle]

I'm not sure you can use a tach light on a diesel (unless it's specially designed). Remember, there is no ignition system on a diesel. The ECM computes the engine RPM from the crank position sensor mounted beneath the crank pulley. It's a magnetic pickup.

 

[1badplr]

Thanks for the reply, what about a wire going to the tach on the dash? There has to be a wire going to that?

 

[rbattelle]

There is no tach wire going to the instrument panel: it's a PCI bus. Basically, that means there's 1 wire that provides communication from the Front Control Module to the instrument cluster, where the signal is de-multiplexed and decoded to derive the various signals for the instruments.



Think of it sort of like the ethernet connection on your computer... there's no one single wire for "TDR".