Test A: No Communication With the 4-Wheel Drive (4WD) Control Module

Pinpoint Test A: No Communication With The 4-Wheel Drive (4WD) Control Module

Test A1:

Test A1-A2:

CAUTION: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.

Normal Operation
The 4WD control module communicates with the diagnostic tool through the universal asynchronous receiver-transmitter (UART)-based protocol (UBP) communications network circuit 693 (OG). If the 4WD control module loses power, it will not be able to communicate. Check power circuit 972 (BK/WH) and ground circuit 1203 (BK/LB) for an open. If the circuits prove out, refer to Information Bus for further diagnostics.

Possible Causes
^ Circuit 972 (BK/WH)
^ Circuit 1203 (BK/LB)
^ 4WD control module
^ Circuit 693 (OG)