Circuit/System Description

The engine control module (ECM) has a 5-volt reference buss for each 5-volt reference circuit. The circuits are called 5-volt reference 1 and 5-volt reference 2. Each bus provides a 5-volt reference 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 bus. The ECM monitors the voltage on the 5-volt reference busses.

The 5-volt reference 1 bus provides 5 volts to the following sensors:

• The exhaust gas recirculation (EGR) valve
• The manifold absolute pressure (MAP) sensor
• The fuel tank pressure (FTP) sensor
• The accelerator pedal position (APP) sensor 2
• The engine oil pressure (EOP) switch
• The air conditioning (A/C) refrigerant pressure sensor
• The camshaft position (CMP) sensor

The 5-volt reference 2 bus provides 5 volts to the following sensors:

• The APP sensor 1
• The throttle position (TP) sensor 1 and 2
• The crankshaft position (CKP) sensor