PCM Controlled Tachometer Diagnosis

Diagnostic Chart:

CIRCUIT DESCRIPTION
The IC Module supplies the tachometer signal to the Instrument Cluster. When the vehicle is started the 7X CKP sensor produces a signal that is received by the IC Module, the module then generates a reference pulse known as the 3X Reference circuit. The module sends this reference signal to the PCM to perform other ignition functions, and to the Instrument Cluster for the tachometer signal.

DIAGNOSTIC AIDS
Refer to Instrument Cluster in Electrical Diagnosis for additional diagnostic information. Refer to Instrument Cluster System Check Inspect for the following conditions: Testing and Inspection

IMPORTANT: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

^ Poor terminal connection.
Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections, and Connector Repairs Diagrams.
^ Damaged harness.
Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Diagrams.
^ Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.