P0651
DTC P0651
CIRCUIT DESCRIPTION
The engine control module (ECM) provides 5 volts to the following sensors:
- The accelerator pedal position (APP) sensor 1
- The throttle position (TP) sensor 1 and 2
- The cooling fan speed sensor (Trailblazer SS only)
- The crankshaft position (CKP) sensor (2006 Corvette and Cadillac CTSv 6.0 only)
These 5-volt reference circuits are independent of each other outside the ECM, but are bussed together inside the ECM. Therefore, a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The ECM monitors the voltage on the 5-volt reference circuit. If the ECM detects that the voltage is out of tolerance, DTC P0651 sets.
DTC DESCRIPTOR
The diagnostic procedure supports the following DTC:
DTC P0651 5-Volt Reference 2 Circuit
CONDITIONS FOR RUNNING THE DTC
- The ignition switch is in the ACC, ON, or Start position.
- The ignition voltage is more than 5.23 volts.
- DTC P0651 runs continuously once the above conditions are met.
CONDITIONS FOR SETTING THE DTC
The ECM detects a voltage out of tolerance condition on the 5-volt reference circuit for more than 0.5 seconds.
ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
- The control module commands the TAC system to operate in the Reduced Engine Power mode.
- A message center or an indicator displays Reduced Engine Power.
- Under certain conditions the control module commands the engine OFF.
CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- 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 emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.
TEST
