The timing calibration sensor is used to calibrate the signal from the engine speed/timing sensors. The timing calibration sensor eliminates any mechanical errors.
 | |
| Illustration 1 | g01265854 |
Typical schematic | |
 | |
| Illustration 2 | g01266479 |
Location of timing calibration probe (typical right side engine view) (1) Timing calibration sensor | |
 | |
| Illustration 3 | g01265855 |
P1 Connector for the Electronic Control Module (ECM) (P1-13) Secondary engine speed/timing signal (P1-33) Primary engine speed/timing signal (P1-40) Engine timing calibration − (P1-41) Engine timing calibration + (P1-43) +13 V supply (P1-51) Digital return | |
 | |
| Illustration 4 | g01234146 |
Location of ECM connectors | |
Test Step 1. Inspect Electrical Connectors and Wiring
- Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.
- Turn the breaker for the ECM to the OFF position.
- Thoroughly inspect the ECM connectors J1/P1. Inspect all of the other connectors in the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the proper procedure for inspecting system wiring.
- Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
- Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
- Check the harness and the wiring for abrasion and for pinch points.
Expected Result:
All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.
Results:
- OK - The harness and wiring are OK. Proceed to Test Step 2.
- Not OK - There is a problem in the connectors and/or wiring.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.
STOP
Test Step 2. Check for a Short Circuit and/or for an Open Circuit in the Timing Calibration Sensor
- Disconnect the connector for the timing calibration sensor.
- Measure the resistance at the connector for the timing calibration sensor between terminal B and terminal C.
- Measure the resistance at the connector for the timing calibration sensor between terminal B and engine ground.
- Measure the resistance at the connector for the timing calibration sensor between terminal C and engine ground.
- Leave the connector for the timing calibration sensor disconnected.
Expected Result:
The resistance between terminal B and terminal C is approximately 142 Ohms. The resistance measurement between terminal B or terminal C and engine ground indicates an open circuit.
Results:
- OK - The resistance measurements are OK. Proceed to Test Step 3.
- Not OK - The resistance measurements are not OK. The timing calibration sensor is internally shorted or open.
Repair: Replace the timing calibration sensor.
STOP
Test Step 3. Check for a Short Circuit in the Wiring Harness
- Disconnect the J1/P1 and J2/P2 ECM connectors.
- Measure the resistance between terminal P1-40 and every terminal on ECM connectors P1 and P2.
- Measure the resistance between terminal P1-40 and engine ground.
- Measure the resistance between terminal P1-41 and every terminal on ECM connectors P1 and P2.
- Measure the resistance between terminal P1-41 and engine ground.
Expected Result:
The resistance measurements indicate an open circuit.
Results:
- OK - The resistance measurements indicate an open circuit. Proceed to Test Step 4.
- Not OK - A resistance measurement indicates a short circuit.
Repair: Repair the connectors or wiring and/or replace the connectors and wiring.
STOP
Test Step 4. Check for an Open Circuit in the Harness
- Use a suitable piece of wire to create a short between terminal B and terminal C on the engine side of the connector for the timing calibration sensor.
- Measure the resistance between terminal P1-40 and terminal P1-41.
- Remove the wire short. Reconnect the ECM connectors.
Expected Result:
The resistance measurement indicates a short circuit.
Results:
- OK - The resistance measurement indicates a short circuit. Proceed to Test Step 5.
- Not OK - The resistance measurement does not indicate a short circuit. There is an open circuit in the wires between the ECM and the connector for the timing calibration sensor.
Repair: Repair the connectors and wiring and/or replace the connectors and wiring.
STOP
Test Step 5. Check the Signal Voltage at the Sensor Connector
- Turn the breaker for the ECM to the ON position.
- Turn the switch that provides power to the keyswitch input for the ECM to the ON position.
- Start the engine and set the engine rpm to low idle.
- Set a multimeter on the 20 VAC position.
- Measure the voltage between terminal B and terminal C at the connector for the timing calibration sensor.
Expected Result:
The signal voltage is greater than 6.0 VAC.
Results:
- OK - A valid signal voltage appears at the ECM connector P1.
Repair: The problem may be intermittent. If the problem is intermittent refer to Troubleshooting, "Inspecting Electrical Connectors" for procedures for inspecting connectors and wiring.
STOP
- Not OK - The signal voltage is less than 6.0 VAC.
Repair: Check the installation of the timing calibration sensor. Refer to the Specifications manual for information on installing the timing calibration sensor.
STOP