PCM Controlled Tachometer Diagnosis

Diagnostic Chart:

CIRCUIT DESCRIPTION
The PCM controls the pulse frequency in relationship to engine RPM, and sends the information via class II to the Instrument Cluster.

DIAGNOSTIC AIDS
Refer to A Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Warning Indicators for additional diagnostic information. Testing and Inspection

Check for the following conditions:
^ Poor connection at the PCM or instrument cluster - Inspect the harness connectors for the following conditions:
^ Backed out terminals
^ Improper mating
^ Broken locks
^ Improperly formed or damaged terminals
^ Poor terminal to wire connection

Refer to Testing for Intermittent and Poor Connections and Connector Repairs and Wiring Repairs in Diagrams.

^ Damaged harness - Inspect the wiring harness for damage. Refer to Testing for Intermittent and Poor Connections and Connector Repairs and Wiring Repairs in Diagrams.