P012

Code PO12:

Distributor Circuit:

DESCRIPTION
The Powertrain Control Module (PCM) checks for CAM HI pulses being received without REF HI (distributor) reference pulses. If the PCM senses no reference pulses, the engine will not start because the fuel delivery system is triggered by the reference pulses and Code P012 is set.

Possible causes of "no distributor reference signal" are:

1. Open or shorts on CKT 430 from ignition control module to PCM.

2. Ignition Control module unable to process pickup coil signals to produce distributor reference pulses.

3. The grounding screw is located on the metal tab that is attached to the plastic fitting on the five wire harness.

TEST CONDITIONS
1. Code P041 not set;

2. Code P041 is tested any time Camshaft Position sensor signals are being received.

FAILURE CONDITIONS
If the PCM does not receive distributor reference pulses (REF HI) for 4 seconds with camshaft position sensor pulses (CAM HI) being received, Code P012 will set.

ACTION TAKEN
PCM turns "ON" the "Service Engine Soon" Malfunction Indicator Lamp (MIL).

NOTES ON FAULT TREE
1. Checking for proper output of ignition system. If voltmeter reads 0.5 - 2.8 volts, ignition control module is receiving pick-up coil signal and producing reference pulses.

2. Checking for proper ground at the PCM and ignition control module.

3. Checking for reference pulses on CKT 430 from the ignition control module to the PCM. If PCM terminal "1D8" has 0.5 - 2.8 volts, then the PCM is receiving reference pulses.

4. Checking for ignition control module operation. If the ignition control module will produce spark, then the fault is not the pickup coil or ignition control module.

NOTE ON INTERMITTENTS
If Code P012 is stored as a history code, start the engine and allow to idle while manipulating CKT 430 and 453. An intermittent open will cause the engine to stumble or quit when the PCM loses distributor reference signals. If the wiring and PCM connectors are OK, check the pickup coil leads for an intermittent open circuit.