P1635

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) uses the 5-volt reference circuit as a sensor feed to the following sensors:
^ The boost sensor.
^ The Crankshaft Position (CKP) sensor.
^ The optical/fuel temperature sensor (CMP/High resolution).

The ECM monitors the voltage on the 5-volt reference circuit. If the voltage is out of tolerance, the ECM will set DTC P1635.

CONDITIONS FOR RUNNING THE DTC
The ignition is in the ON position.

CONDITIONS FOR SETTING THE DTC
A 5-volt reference is less than 1 volt.

ACTION TAKEN WHEN THE DTC SETS
^ The control module stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
^ The driver information center, if equipped, may display a message.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC "Last Test Failed" clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Use a scan tool in order to clear the DTC.

DIAGNOSTIC AIDS
During the time the failure is present, the setting of additional DTCs that share a 5-volt reference may also set.

TEST DESCRIPTION

Steps 1-13:

The numbers below refer to the step numbers on the diagnostic table.
2. This step checks to confirm that a DTC is still present.
3. This step checks to determine if there is a 5-volt reference from the PCM.
4. This step checks to determine if there is a short to ground in the reference circuit or a short to ground in the PCM.
7. This step determines if the short is being caused by one of the sensors on the engine or the short is in the wiring harness.