Chart B-2 Loss of BCM Data to IPC

Chart:

Schematic:

You are on this chart because the odometer, at key on, read all zeroes and the courtesy lamps turned on when the switch was actuated. These symptoms indicate a loss of Body Control Module (BCM) data communication to the Instrument Panel Cluster (IPC), which is the result of one of several different possible problems.

TEST DESCRIPTION
The numbers below refer to circled numbers on the diagnostic chart:
1. If the ALDL connector cover is off or loose, this could cause a break in the data circuit cutting off BCM communication to the IPC under certain electrical conditions. Should this be the case, securely connect the ALDL cover and return to the beginning of the Diagnostic System Check.
2. This step isolates the ALDL connector, the Electronic Control Module (ECM) and the programmer from the data circuit in order to determine the location of the fault. If the odometer reads actual accumulated miles, then the fault lies within the network between the ALDL connector, the ECM and the programmer.
3. If the odometer, at this point reads all zeroes, the fault is in the component or related wiring of the BCM, IPC, Climate Control Driver Information Center (CCDIC), or Central Power Supply (CPS).
4. This step determines if the fault is due to the data circuit at the CCDIC.
5. This step determines if the fault is due to the CCDIC, the logic ground CKT 801 from the CPS or the CPS.
6. This step checks to see if the fault is due to the ECM and its related data circuits or the programmer and its related circuits.
7. This step determines if the fault is the ECM or the data CKT 800H, 800E, or 800F.
8. This step determines if the fault is due to the programmer, the programmer's logic ground CKT 801 from the CPS.