Circuit/System Description
WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The engine control module (ECM) has 2 internal 5-volt reference busses called 5-volt reference 1 and 5-volt reference 2. Each reference buss provides 5-volt reference circuits for more than one sensor. A fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to that reference buss. The ECM monitors the voltage on the 5-volt reference buss.
The 5-volt reference 1 buss provides 5 volts to the following sensors:
- The manifold absolute pressure (MAP) sensor
- The fuel tank pressure (FTP) sensor
- The air conditioning (A/C) refrigerant pressure sensor
- The accelerator pedal position (APP) sensor 2
- The exhaust camshaft position (CMP) sensor
- The intake CMP sensor
The 5-volt reference 2 buss provides 5 volts to the following sensors:
- The APP sensor 1
- The throttle position (TP) sensor 1 and 2
- The crankshaft position (CKP) sensor
- The secondary air injection (AIR) solenoid