Join Date: Apr 2001
Location: Dublin, Ireland
Locating The Tach Wire
I'm going to be installing a Clifford alarm in my 145 shortly and part of the install involves locating the tach wire. The instructions are as follows(it's a bit lengthly):
Some newer vehicles do not have a conventional coil marked (+) and (—). In these instances, you will need to locate the tach wire:
1. Try to locate the distributor cap which all spark plug wires run in to. There should be the same number of plug wires as the number of cylinders. If there is an extra plug wire, the vehicle has a separate coil.
2.Follow the extra plug wire to the coil module, which will have two or more wires.
a. If there are only two wires: one is the ignition, the other wire is the negative coil wire.
b. If there are more than two wires, only an oscilloscope will be 100% accurate in locating the tach wire, but a digital voltmeter will often suffice. Set the meter to read AC voltage, connect the negative lead of the meter to earth and probe the wire with the positive lead. The wire that has the highest AC voltage while the engine is running is usually the tach wire.
3. If the vehicle does not have a separate coil, look for the tach wire in a plug coming out of the distributor. If no distributor can be found, the vehicle may have multiple coils. Each coil usually has an ignition and a negative coil wire. Clifford systems will learn a single or multiple coil system.
4. On almost all fuel injected vehicles, you can connect to the negative side of any fuel injector. Most fuel injectors are screwed
directly into the engine and typically have two wires. One is ignition and usually has a colour common to all fuel injectors, the
other is the negative side and can be tested as described in step 2b above.
1.Installation Option 1 — Negative Coil
Connect the BLACK/GRAY wire to the negative terminal of the ignition coil, nor mally marked (—).
2. Installation Option 2 — Fuel Injector Wire
a. Locate the injector wire. On many engines with electronic fuel injection, there are two wires going to each injector: a
fuel-injector wire and a common ignition wire. The common ignition wire is usually the same color a t each injector (and may
also be the same color as the ignition line in the steering column). The injector wire is the other wire.
b. Connect the BLACK/GRAY wire to one of the injector wires at one of the injectors.
3.Installation Option 3 — Tachometer Terminal (Not all cars have a tachometer terminal — mostly older GM models have a
a. Locate the tachometer terminal on the distributor cap (this may be marked as “tach”).
b. Connect the BLACK/GRAY wire to the tachometer terminal.
Given the rather unconventional wiring involved in a twinspark engine can some please tell me how the above instructions can be applied to a TS or at least can someone explain the anatomy of the TS wiring system so I can puzzle it out...