Circuit Description

The engine control module (ECM) provides 5 volts to the following sensors:

• The manifold absolute pressure (MAP) sensor
• The engine oil pressure (EOP) sensor
• The fuel tank pressure (FTP) sensor
• The air conditioning (A/C) refrigerant pressure sensor
• The accelerator pedal position (APP) sensor 2
• The camshaft position (CMP) 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 P0641 sets.