Ignition Timing Connector: Testing and Inspection

Ignition Coil And Power Transistor Circuit:

OPERATION
The ignition timing adjustment signal, is manually grounded by the technician to remove the ECU's control of the ignition timing. This is needed to adjust the base ignition timing setting. If the circuit becomes grounded at any time, ECU control of the ignition system is disabled, the "Malfunction Indicator Light" will come on, and the ECU will store a trouble code. Operation of the vehicle under these conditions can result in loss of power and engine overheating.

OPERATION TEST
1. Start and warm the engine until the coolant temperature exceeds 80°C (176°F).
2. Connect a timing light to ignition wire #1.
3. Observe ignition timing and note position of marks.
4. Connect jumper wire between ignition timing adjustment connector #1 and ground.
4. Observe ignition timing marks. Verify that the marks are now at specified base timing setting.

IGNITION TIMING:
5° BTDC ± 2°

5. If the ignition timing does not change, perform the harness test.


HARNESS TEST
1. With the ignition switch in the off position, check for continuity between the ignition timing adjustment connector and ground.

CONTINUITY:
Should Not Exist

2. Turn ignition switch to the on position.
3. Connect a volt meter between the ignition timing adjustment connector and ground.
3. Measure the voltage.

VOLTAGE:
4.0 - 5.2 Volts


If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, clear the trouble codes and road test the vehicle to confirm that the repair has corrected the problem and the code doesn't return.

If the same trouble code reoccurs, it is possible that there is an intermittent failure of the component or the ECU. Check for looseness at all harness junctions and test for an intermittent failure.