- Multimeter
- Wire stripper
- Crimpers
- Tachometer with wire leads
1. Identify the tachometer wire on your tachometer. This wire is typically labeled "TAC" or "RPM."
2. Locate the negative (-) terminal on your tachometer. This terminal is typically marked with a black wire or a minus (-) symbol.
3. Locate the positive (+) terminal on your tachometer. This terminal is typically marked with a red wire or a plus (+) symbol.
4. Locate the ignition coil for the cylinder you want to measure the RPM of.
5. Find the connector at the ignition coil with two wires. The ignition coil should have a three-pin connector. The two wires you are looking for will be the black/white and orange wires.
6. Strip the ends of the tachometer wire leads.
7. Connect the black tachometer wire lead to the negative (-) terminal on your tachometer.
8. Connect the red tachometer wire lead to the positive (+) terminal on your tachometer.
9. Connect the black/white tachometer wire lead to the negative terminal of your ignition coil.
10. Connect the orange tachometer wire lead to the positive terminal of your ignition coil.
11. Turn on your tachometer and start your engine.
12. Adjust the sensitivity of your tachometer, if necessary, so that it reads correctly.
Once you have completed these steps, your tachometer should be properly connected to your GMC 4-cylinder engine with coil packs and will display the RPM of the engine.
