Chart B7 - BCM-To-Cps Wake-Up Signal Problem

You are at this chart because odometer, with key on, read all 8's, was blank, high beams would not cycle, courtesy lights would not turn on, but lights on chime would sound when activated. These symptoms indicate a loss of 7 volts from Central Power Supply (CPS) to data network components, used to power the microprocessor chip. Or, the CPS has lost system wake-up signal from BCM, which is used to turn on 7 volt power supply.

1. This step checks circuit No. 555, CPS wake-up signal, for a short to ground, a fault in BCM or BCM connector, or a bad CPS.
2. This step checks for an open in circuit No. 555.
3. This step checks for an open circuit in CPS ground, which will disable 7-volt power supply.
4. This step checks for short to ground in each 7-volt circuit from CPS, for a faulty component in network, or a faulty CPS.

Fig 1: Flow Chart B7, BCM-To-CPS Wake-Up Signal Problem

Fig 2: Flow Chart B7, BCM-To-CPS Wake-Up Signal Problem