Circuit Description

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 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 the voltage is out of tolerance, DTC P0641 sets.