Diagnostic Aids

Scan tool parameter values for TP sensor, MAP sensor, EGR sensor and fuel tank pressure sensor may only shift slightly if a short to ground or voltage on 5-volt reference circuit occurs. ECT, IAT, FUEL LEVEL and IGNITION 1 voltage parameters on scan tool may not appear normal if DTC P1635 is active.

To locate an intermittent problem, use scan tool to monitor DTC P1635 LAST TEST with ignition on, engine off. Scan tool will display FAILED if a short on 5-volt reference circuit exists.

DTCs P0562, P0563 and P0711 may set if a short to ground exists on the 5-volt reference circuit.

DTCs P0561, P0562 and P0711 may set if a short to battery voltage exists on the 5-volt reference circuit. Driveability conditions will exist if a short on the 5-volt reference circuit is present.

A short to battery voltage on the 5-volt reference circuit will not set P1635 (PCM service part #21024985 or 21024986).