Powertrain Diagnosis

Diagnostic Chart:

Wiring Diagram:

The coolant temperature gauge is directly controlled by the PCM using a pulse width modulated (PWM) signal, based on information from the engine coolant temperature (ECT) sensor. The PCM uses the inputs from the ECT to control fuel, the A/C cooling fan and the low coolant/hot lamp. The ECT is the only coolant temperature sensing device on both SOHC and DOHC engines.

DTC PARAMETERS
DTC P1691 will set if there is an open, short to ground or short to voltage in the coolant gauge circuit.

IMPORTANT: The coolant gauge circuit is continuously checked when the ignition is On.

DIAGNOSTIC AIDS
If the Scan tool Malf history indicates an open/short to power or ground, refer to the coolant circuit gauge diagnosis on next page.

A Scan tool may be used to command the coolant gauge. Diagnosis of coolant gauge accuracy can be found in the "Audio System and I/P Cluster Service Manual."