For 1990-2009 cars

The powertrain control module (PCM) controls spark timing and dwell (spark On-time) under all engine running conditions. The electronic ignition (EI) module has the ability to charge and discharge the coil packs based on PCM control. The PCM uses a high control signal of near 5 volts to charge up the coil and a low control signal of near 0 volts to discharge the coil. If the coil is charged and the control signal is low, the coil will fire through its secondary towers. DTC P0351 sets when a short to ground exists on ignition control (IC) circuit 1 and 4 during engine crank or when the engine is running.

### DTC Parameters

DTC P0351 will set if a short to ground occurs on IC circuit 1 and 4 when:

• | The condition exists for longer than 0.5 seconds.

• | The engine is cranking or running.

DTC P0351 diagnostic runs continuously when the engine is cranking or running.

DTC P0351 is a type D DTC.

### Diagnostic Aids

The IC circuit 1 and 4 consists of the EI module, circuit 423 and the PCM.

Voltage on circuit 423 with EI module disconnected and ignition ON, engine OFF should read between 3.5-5 volts.

A short to ground on IC circuit 1 and 4 will cause a misfire on both cylinders 1 and 4. Use the scan tool to monitor MISFIRE CURRENT CYLS #1 and #4 to locate an intermittent problem.

The IGN COIL 1 AND 4-LOW VOLT test parameter on scan tool can also be used to locate an intermittent problem. If a fault (short to ground) occurs when engine is running, the scan tool will display TEST FAIL.

A secondary ignition problem on cylinder #1 or #4 will NOT cause DTC P0351 to set.