P0336

Circuit Description
The 24X reference signal is used to improve idle spark control at low engine speeds. The PCM uses the 24X reference signal to calculate engine rpm and crankshaft position at engine speeds below 1200 rpm. The PCM constantly monitors the number of pulses on the 24X reference circuit and compares the number of 24X reference pulses to the number of 3X reference pulses and CAM signal pulses being received. If the PCM receives an incorrect number of pulses on the 24X reference circuit, DTC P0336 will set and the PCM will use the 3X reference signal circuit for fuel and ignition control. The engine will continue to start and run using the 3X reference and CAM signals only.

Conditions for Running the DTC
The engine is running (3X reference pulses are being received).

Conditions for Setting the DTC
^ The ratio of 3X reference pulses to Cam pulses received equals 6:1.
^ The ratio of 24X reference pulses to 3X reference pulses received does not equal 8:1.
^ The condition is present for up to 300 3X reference periods (100 crankshaft revolutions).

Action Taken When the DTC Sets
^ The PCM will illuminate the MIL during the second consecutive trip in which the diagnostic test has been run and failed.
^ The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC
^ The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been run and passed.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids
DTC P0336 can be caused by secondary components leaking high voltage into the ignition module. Check for the following conditions:
^ Incorrect harness routing near secondary ignition components.
^ Ignition coil arcing to wiring harness or Ignition Control Module (check ignition coils for cracks, carbon tracking, or other signs of damage).
^ Secondary ignition wire(s) arcing to wiring harness.
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for:
^ Poor connection. Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
^ Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM, turn the ignition on and observe a voltmeter connected to the 24X reference circuit at the PCM harness connector while moving connectors and wiring harnesses related to the 24X Crankshaft Position Sensor and Camshaft Position Sensor. The 24X and Camshaft Position sensors share the same sensor feed from the PCM. A change in voltage will indicate the location of the fault.
It also may be helpful to monitor the 24X rpm on the scan tool, to look for erratic rpm fluctuations. Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
14. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed. Refer to Powertrain Control Module / Service and Repair.