Circuit Description
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The DTC P0651 5 Volt Reference 2 Circuit diagnostic detects an incorrect voltage on the reference B supply circuit. The powertrain control module (PCM) provides 5 volts to the reference B circuit to the following sensors:
- The accelerator pedal position (APP) sensor 2
- The fuel tank pressure (FTP) sensor
- The exhaust gas recirculation (EGR) sensor
- The automatic transmission input shaft speed (AT ISS) sensor
- The air conditioning (A/C) pressure sensor
These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a short circuit condition on the 5-volt reference of one sensor can affect the operation of the other sensors. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0651 sets.