P1351

Schematic:

CIRCUIT DESCRIPTION
The enhanced ignition system uses the Crankshaft Position (CKP) sensor in order to provide a timing input to the control module. Ignition Control (IC) spark timing for each cylinder is based on this input. The control module provides 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 more than 4.9 volts.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
^ The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame and Failure Records.

CONDITIONS FOR CLEARING THE MIL OR DTC
^ The control module 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. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
^ Use a scan tool in order to clear the DTCs.

DIAGNOSTIC AIDS
Intermittent test - If the connections and the harness check OK, monitor a DMM 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 inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections in Diagrams.

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

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. This step 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.