Ignition Timing
- Set parking brake, block drive wheels and place transmission in Neutral or Park. Warm engine to normal operating temperature. Turn A/C off (if equipped). Ensure Malfunction Indicator Light (MIL) is off.
- Disconnect Tan/Black Electronic Spark Timing (EST) by-pass connector wire. On 4.3L, by-pass connector is on wiring harness conduit near distributor. On other models, by-pass connector is located near heater housing in passenger compartment. On all models, DO NOT disconnect 4-wire connector at distributor.
- Connect timing light to No. 1 spark plug wire. Check timing and adjust if necessary. See IGNITION TIMING . Reconnect EST by-pass connector, and clear ECM trouble code.
IGNITION TIMING (DEGREES BTDC @ RPM)
| Application | Man. Trans. | Auto. Trans. |
|---|---|---|
| 4.3L (VIN W & Z) | 0 @ Idle | 0 @ Idle |