Home Auto Repair How to Hook Up a Timing Light

How to Hook Up a Timing Light


Timing lights are a diagnostic tool used on cars without computer-controlled ignition to help the mechanic find the correct setting for ignition timing. Proper timing on a car improves fuel mileage, engine longevity and performance. The device resembles a gun with a flat front and three wires hanging from it. These are connected to the battery and spark plug wire prior to use. To determine which spark plug wire is connected to the first piston, check your vehicle’s owner’s manual for the firing order diagram of the engine. Hook up a timing light properly to set accurate timing, avoid arcing of electricity and prevent engine damage.

Step 1: Lift and prop the hood while the car engine is off.

Step 2: Disconnect the vacuum line from the distributor and plug it with the pencil tip. Be sure not to break the lead. Rest the pencil in a safe place.

Step 3: Grasp the red wire alligator clip on the timing light. Hook it to the positive battery terminal of the vehicle.