E012

Diagnostic Chart.:

Wiring Diagram.:

DESCRIPTION:

Possible causes of "no distributor reference" are:

1. The grounding screw is located on the metal tab that is attached to the plastic fitting on the five wire harness.
2. HEI module unable to process pick up coil signals to produce distributor reference pulses.
3. Open or shorts on CKT 430 from distributor module to PCM.
4. Defective pick up coil.


TEST CONDITIONS:

1. Code E41 not set.

2. Code E12 is tested any time the cam sensor signals are being received.

FAILURE CONDITIONS:

If the PCM does not see distributor reference pulses for 4.0 seconds with cam reference pulses being received, current code E12 will be set.

ACTION TAKEN:

1. The PCM/ECM turns on "SERVICE ENGINE SOON" telltale.

NOTES ON FAULT TREE:

1. Checking for proper voltage output of the HEI system. If the voltmeter shows .5 to 2.8 volts, then HEI is producing reference pulses.

2. Checking for proper ground connection between the PCM and the HEI module.

3. Checking for proper voltage through CKT 43O from HEI to the PCM. If PCM terminal D8 sees .5 to 2.8 volts, then the PCM is receiving reference pulses.

4. Checking for HEI module operation. If the HEI system will produce a spark then fault is not at the pick up coil or module.

NOTE ON INTERMITTENTS:

If code E012 is stored as a history code, start engine and allow to idle while manipulating CKT's 430 and 453. An intermittent open will cause the engine to stumble or quit when the PCM loses distributor reference.

If wiring and PCM connectors are OK, check the HEI pick up coil leads for an intermittent open circuit.