1996 Chevrolet K Pickup - 4WD | Chevy Pickup, GMC Pickup, Suburban, Tahoe, Yukon VIN C/K Service Manual | Document ID: 34079
DTC P1351 Ignition Coil Control Circuit High Voltage
Circuit Description
The enhanced ignition system uses the crank sensor in order to provide the timing input to the VCM. The VCM uses this reference pulse in order to determine the individual ignition spark timing for each cylinder.
Once the VCM calculates the ignition timing, the ignition coil module on the IC circuit receives the timing signal. Each timing pulse received by the ignition coil module on the IC circuit triggers the coil module in order to operate the ignition coil. The secondary ignition voltage is induced, and then the secondary ignition voltage is sent to the distributor for distribution to each spark plug. This DTC is a type A DTC.
The IC signal voltage ranges from about 0.5 volt to 4.5 volts.
Conditions for Setting the DTC
The voltage on the ignition control circuit exceeds 4.9 volts, and the engine speed is less than 250RPM.
• The VCM turns the MIL ON 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 driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (the coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle) or the scan tool clearing feature has been used.
Diagnostic Aids
A poor connection, a rubbed through wire in the insulation, or a wire broken inside the insulation will cause an intermittent.
Check for the following conditions:
• Poor connection
• Damaged harness: Inspect the VCM harness connectors for the following conditions:
– Backed out terminal C3 pin 9
– Improper mating
– Broken locks
– Improperly formed or damaged terminals
– A poor terminal to wire connection and
– Damage to the harness.
• Intermittent test - If the connections and the harness check OK, monitor a digital voltmeter connected between VCM connector 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.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
2. This determines if the DTC is an intermittent.3. This check determines if the IC signal from the VCM is available at the ignition coil driver. 4. The remaining tests begin to check that the coil driver circuitry is OK.
DTC P1351 Ignition Coil Control Circuit High Voltage
Step Action Value(s) Yes No
1
Important: Before clearing DTCs, use the scan tool in order to record the freeze frame and the failure records for reference because the Clear Info function will lose the data.
Was the Powertrain On-Board Diagnostic (OBD) System Check performed?
