Powertrain Diagnosis

Diagnostic Chart:

Wiring Diagram:

The tachometer is directly controlled by the PCM using a pulse width modulated (PWM) signal based on information received from the crankshaft position (CKP) sensor. When the key is On, the PCM receives battery voltage from the instrument panel cluster (IPC circuit 121) and senses if the circuit contains a fault by using a diagnostic feedback signal. The PCM provides the ground for the tach signal directly.

DTC PARAMETERS
DTC P1693 will set if there is an open, short to ground or short to voltage in the tachometer circuit.

IMPORTANT: The tachometer diagnostic feedback signal is continuously checked when the ignition is On. The tachometer is not controllable by the Scan tool.

DIAGNOSTIC AIDS
Use the Scan tool to read engine rpm. If rpm is correct, circuit 121 or tachometer is at fault (refer to diagnostic trouble tree).