P1635

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) uses the 5-volt reference A circuit as a sensor feed to the following sensors:
^ The Fuel Tank Pressure (FTP) sensor
^ The Throttle Position (TP) sensor
^ The Manifold Absolute Pressure (MAP) sensor
^ The Exhaust Gas Recirculation (EGR) valve pintle position sensor
^ The engine oil pressure sensor

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

CONDITIONS FOR RUNNING THE DTC
The engine is running.

CONDITIONS FOR SETTING THE DTC
^ The PCM detects a voltage out of tolerance condition on the 5-volt reference A circuit.
^ The above condition is present for longer than 10 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ First failure:
- The MIL is not turned ON.
- A DTC is stored in memory under Failed Last Test.
- The Failure Records are stored.
^ Second consecutive drive cycle with a failure:
- The MIL is turned ON.
- A DTC is stored in memory under history.
- The Freeze Frame data is stored.
- The Failure Records are stored.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after the third consecutive trip the diagnostic has run and passed.
^ The history DTC will clear if the fault conditions have not been detected for 40 warm-up cycles.
^ A scan tool can be used to clear DTC information.

TEST DESCRIPTION

Steps 1-5:

Steps 6-14:

The number below refers to the step number on the diagnostic table.
12. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.