Set Timing Mode

The set timing mode instructs the ECM to control spark timing to the 10° BTDC base timing setting to allow setting and verification of spark timing. To enter the set timing mode, proceed as follows:
1. Start engine and run until coolant temperature reaches 85°C.
2. Ensure transmission is in Park position and engine idle speed is less than 900 RPM.
3. Exit diagnostics by depressing Off button on CCP until display returns to standard climate control mode.
4. Connect suitable jumper wire between ALDL connector pins A and B. ``Set Timing'' will be displayed and engine will operate at base idle. At this point, timing can be checked with a standard timing light.
5. Exit set timing mode by removing jumper wire from connector.