P1351

DTC P1351 IC Circuit High Voltage




Circuit Description
The Enhanced Ignition system uses the Crankshaft Position sensor in order to provide a timing input to the VCM. The VCM calculates Ignition Control (IC) spark timing for each cylinder based on this input. The VCM applies the Ignition Timing Signal to the Ignition Control Module (ICM) to control the Ignition Coil. Each timing pulse detected by the ICM allows it to energize the Ignition coil. A large Secondary ignition voltage is induced in the secondary coil by the primary coil. This high voltage is switched to the correct spark plug by the distributor.

This DTC will set if the VCM detects an unusually high voltage on the ignition timing signal circuit.

Conditions for Running the DTC
- The ignition control is enabled.
- The engine speed is less than 250 RPM.

Conditions for Setting the DTC
The ignition control voltage is greater than 4.9 volts.

Action Taken When the DTC Sets
- The VCM illuminates the MIL when this DTC is reported and one failure has occurred.
- The VCM records the operating conditions at the time the Diagnostic Fails. Freeze Frame and Failure Records store this information.

Conditions for Clearing the MIL/DTC
- The VCM turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
- A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22 °C (40 °F) from the startup coolant temperature and the engine coolant temperature is more than 70 °C (158 °F) during the same ignition cycle).
- Use the scan tool Clear Information function.

Diagnostic Aids
Intermittent test - If the connections and the harness check OK, monitor a digital voltmeter connected between VCM terminal C3 pin 9 and C4 pin 18 while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change. This may help to isolate the location of the malfunction.

An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs.

Steps 1 - 3:

Steps 4 - 9:

Steps 10 - 15:

Steps 16 - 19:

Test Description
The numbers below refer to the step numbers in the diagnostic table.
2. This test determines if the DTC is an intermittent.
3. This step checks if the IC signal from the VCM is available at the ignition control module.