P0323

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The distributor ignition system supplies two timing inputs to the PCM, a high resolution signal (180 pulses per one crankshaft revolution) and a low resolution signal (4 pulses per one crankshaft revolution). The PCM can determine if one of the timing inputs is not being received by comparing the two inputs.

The high and low resolution circuits toggle between 0 and 5 volts as the camshaft turns. The following intermittent malfunctions to the low resolution circuit may cause a DTC P0323 to set:

^ An open.

^ A short to voltage.

^ A short to ground.

^ A detective ignition module within the distributor.

CONDITIONS FOR SETTING THE DTC

^ The PCM detects an interruption in the either the low or high resolution signal.

ACTION TAKEN WHEN THE DTC SETS

^ The DTC will be stored in the PCM memory when the diagnostic runs and fails.

^ The Malfunction Indicator Lamp (MIL) will not illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

^ A history DTC will clear after 40 consecutive warm-up cycles, it no failures are reported by this or any other non-emission related diagnostic.

^ A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.

^ PCM battery voltage is interrupted.

^ Using a scan tool.

DIAGNOSTIC AIDS

^ When DTC P0323 occurs, a misfire may be apparent. To locate an intermittent, use the scan tools snapshot feature. Try to duplicate the conditions under which the misfire is present. When reviewing captured data, watch for any abnormal high and low resolution timing pulses.

^ For intermittents, refer to Symptoms. Testing and Inspection

TEST DESCRIPTION

Number(s) below refer to step numbers on the diagnostic table.

5. Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that were noted.

8. A defective ignition module within the distributor could cause this DTC to set. Inspect the distributor for signs of damage including contamination. Refer to Ignition System. If distributor components must be replaced, check distributor vent system operation. Refer to Distributor Vent System Check