Diagnostic Aids

P0641 

The 5V reference 1 circuit provides 5 V to the sensors listed below:

• Accelerator pedal position sensor 2
• Air conditioning (A/C) refrigerant pressure sensor
• Camshaft position sensor
• Engine oil pressure sensor
• Fuel tank pressure sensor
• Manifold absolute pressure sensor

P0651 

The 5V reference 2 circuit provides 5 V to the sensors listed below:

• Accelerator pedal position sensor 1
• Brake booster vacuum sensor
• Brake pedal position sensor (automatic transmission)
• Clutch pedal position sensor (manual transmission)
• Crankshaft position sensor
• Throttle position sensor 1 and 2

Disconnecting one component at a time from the affected 5V reference circuit while observing the scan tool 5V Reference Circuit Status parameter may help locate the fault. The scan tool parameter will change from Malfunction to OK when the source of the fault is disconnected. If all 5V reference components have been disconnected and a fault is still indicated, the fault may exist in the wiring harness.