For B110 (early 1200) this is how the tachometer goes into the dash

* Red/green wires are for the lights. Plugs into cluster
* Black wire is earth/ground. Plugs into cluster
* Yellow/red wire is Power. Plugs into cluster




* two Black/white wires are IGN signal. Plugs into the dash harness

Cars without tachometer have the wiring in place (utes do not have this). This is a BW wire along the top of the instrument cluster, usually with a bit of blue or yellow tape covering it

Pull the dash harness wires apart at the connectors, and plug them into the BW wires of the tachometer

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  tacho wiring.jpg (86.76 KB)

Interesting, why is the tacho signal wire looped?

I don't really know why it is an actual loop of wire. Anyone know?

As an inductive tachometer, it doesn't measure the signal directly as do most (it doesn't touch the metal of the wire), but instead it just listens to it right through the insulation. Like how an inductive timing light clips around a spark plug lead




This means you can pick up the signal anywhere on the wire from the IGN switch to the coil. Fortunately, at the factory they cut the wire just above the headlight switch and connected it back together. So you can pull the connectors apart and plug the loop wire in, that way there will be no break in the wire to the coil, but now the tachometer can sense the current starting and stopping every time the points open. Many new tachometers still work this way

You can even detect the signal on the other side (between coil and distributor), but why bother as you'd have to run the wire all the way there and back. When you can just get the signal off the closest dash wire ...

It's a loop to make the signal stronger. Since the wire goes through the sensor twice it's twice as strong.

When I modified mine to run off a high impedance tach signal (i.e.a voltage signal) I made a small coil to fit around the sensor and drove it with a transistor. Part of the reason I did it was because I was getting noise/ false triggering out of the ignition I had at the time.