Chart B6: IPCTO-Cps Power/Ground Problem
You are at this chart because odometer, with key on, read all 8's or was blank, the high beams would not cycle, but courtesy light came on when switch was activated. These symptoms indicate Instrument Panel Cluster (IPC) has lost 12-volt power feed or ground with Central Power Supply (CPS).
Test Number 1) Checking CCDIC display indicates whether IPC has ground.
Test Number 2) Disconnecting IPC and checking resistance in circuit No. 801A determines if fault is due to IPC, wiring and terminals, or the CPS.
Test Number 3) This checks if 12 volts is available from the CPS. If not, fault is due to wiring or CPS.
Test Number 4) With 12 volts available from CPS, this checks if fault is due to IPC or flex circuit between transition block and IPC.