P1635
Diagnostic Chart:
Schematic:
The 5 volt reference circuit provides reference voltage to the EGR valve position sensor, fuel tank pressure sensor, Manifold Absolute Pressure (MAP) sensor and Throttle Position (TP) sensor. The current for each 5 volt reference circuit flows through the sensor to ground, which is provided internal to the PCM. The PCM regulates the 5 volt reference voltage to 5 volts under all normal operating conditions. This is necessary for accurate sensor information. The PCM monitors the 5 volt reference circuit for low and high voltage faults. DTC P1635 sets when the 5 volt reference circuit is below a calibrated voltage.
DTC PARAMETERS
DTC P1635 will set if the 5 volt reference circuit is less than 4.75 volts.
DTC P1635 diagnostic runs continuously with ignition On.
DTC P1635 is a type A DTC.
DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to monitor any of the sensors tied to the 5 volt reference circuit. Wiggling wires while watching for a change in any one of the sensors may locate the area where a short to ground or short to voltage on the 5 volt reference circuit could lie.
If all four sensors tied to the reference circuit set low sensor voltage DTCs with P1635 set, a short to ground probably exists on the 5 volt reference circuit.
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 direct battery voltage exists on the 5 volt reference circuit.
Driveability conditions will exist if a short on the 5 volt reference circuit is present.
IMPORTANT: A short to B+ on the 5 volt reference circuit will NOT set P1635.