Circuit Description
WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. 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 (Pontiac)
- The air conditioning (A/C) refrigerant pressure sensor (Buick)
- The exhaust gas recirculation (EGR) valve
- The fuel tank pressure (FTP) sensor
- The secondary AIR pressure sensor (L26, NU3 only)
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.