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

PINPOINT TEST A: NO COMMUNICATION WITH THE 4WD CONTROL MODULE
Refer to Vehicle/Diagrams, Four-Wheel Drive System for schematic and connector information.

Normal Operation
In order for the 4WD control module to communicate with the scan tool, the operating voltage required to supply the 4WD control module is in a range between 9 and 16 volts. Hot-at-all times voltage is supplied by circuit SBP28 (GN/RD); ground is supplied by circuit GD174B (BK/WH).

Possible Causes
^ Power supply circuit SBP28 (GN/RD)
^ Smart junction box (SJB) fuse 28 (15A)
^ Ground circuit:
- GD174B (BK/WH)
^ Charging system
^ Battery

A1-A4:

A4-A6:

A6: