Chart B-2 Loss of BCM Data to IPC

Chart B-2:

No Data Displayed Circuit:

DESCRIPTION:

This chart is used 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 BCM data communication to the IPC, which is the result of one of several different possible problems.


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 SELF-DIAGNOSTIC CIRCUIT CHECK.

2. This step isolates the ALDL connector, the 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. 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.

4. This step will determine if the condition is associated with the IPC or the BCM.

5. This step determines if the fault is due to the programmer, the programmer's logic or, ground CKT 801 from the CPS.