Circuit Description
WARNING: This page is about a different car, the 2004 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
The powertrain control module (PCM) provides 5 volts to the following sensors:
- The manifold absolute pressure (MAP) sensor
- The exhaust gas recirculation (EGR) valve
- The fuel tank pressure (FTP) sensor
- The throttle position (TP) sensor
These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0641 sets.