Chart B-4, BCM-To-Cps Power/Ground Problem

You are at this chart because odometer, with key on, read all zeroes and courtesy lights did not turn on when switch was actuated. These symptoms indicate BCM has lost power or ground with Central Power Supply (CPS).

1. This checks maximum blower speed with key on. Step will indicate whether the BCM has lost logic ground circuit No. 801E with CPS.
2. This determines if loss of logic ground is due to BCM, CPS or circuit No. 801E wire and terminals.
3. This checks 12 volts to BCM. If 12 volts is not present at BCM, fault is due to CPS or wiring.
4. This checks 7 volts to BCM, which has 2 individual inputs fed from CPS. Loss of both signals would result in system fault, otherwise fault is due to a bad CPS or BCM.

Fig 1: Chart B-4, Schematic, BCM-To-CPS Power/Ground Problem

Fig 2: Flow Chart B-4, BCM-To-CPS Power/Ground Problem