Circuit/System Description

The control module has 2 internal 5-volt reference busses called 5-volt reference 1 and 5-volt reference 2. Each reference bus provides 5-volt reference circuits for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to that reference bus. The control module monitors the voltage on the 5-volt reference busses.

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

• The manifold absolute pressure (MAP) sensor
• The fuel tank pressure (FTP) sensor
• AIR pressure sensor
• The exhaust gas recirculation (EGR) valve

The 5-volt reference 2 bus provides 5 volts to the air conditioning (A/C) refrigerant pressure sensor