Ignition Timing: Adjustments

ALDL Connector:

PROCEDURE
1. With ignition off, connect the pick-up lead of the timing light to the number one spark plug wire. Do NOT pierce the wire or attempt to insert a probe between the boot and the wire. Connect the timing light power leads.

2. Jumper pins A & B together at the ALDL connector while not in diagnostic display mode. The ALDL connector is located above a hatch in the hush panel at the center of the dash. Jumpering pin A to pin B of the ALDL connector will cause the "SERVICE ENGINE SOON" light to flicker which indicates that the ECM is in "set timing mode".

3. Start the engine and aim the timing light at the timing mark. The line on the pulley will line up at the timing mark. If a change is necessary, loosen the distributor hold-down clamp bolt with special tool J-29791 or equivalent, at the base of the distributor. While observing the mark with the timing light, slightly rotate the distributor until the line indicates the correct specification. Tighten the hold-down bolt and re-check the timing.

4. Turn off the engine and remove the timing light. Reconnect the number one spark plug wire, if removed.

CAUTION: Do not time the engine on seven cylinders since the unburned fuel could cause damage to the catalytic converter.