Chart B-5, Serial Data Circuit Open
The serial data line, with the exception of the ECM, is redundant with all the devices that communicate with it. While only one line need be connected to each device for the system to function, when making repairs, both lines should be made to communicate. If the system shuts down when the ALDL cover is removed, a single open existed and a second open is being created by removing the ALCL cover.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- This step checks for serial data to the IPC. If less than one volt, re-establish serial data communications with the BCM before proceeding.
- With serial voltage at the proper level, the fault is poor contact between the ECM and the IPC.