Test Q: Transmission 4-Wheel Drive Mode Select Switch Failure
Test Q: Transmission 4-Wheel Drive Mode Select Switch FailureQ1-Q2:
Q3-Q5:
Q5-Q7:
Q7:
Normal Operation
The mode select switch (MSS) communicates the operator's choice to the 4WD control module (GEM). The 4WD control module (GEM) controls the shift solenoid, transfer case motor and pulse vacuum hublocks (PVHs) as necessary. If the vehicle is not responding to the operator's intentions, systematically check the necessary inputs and outputs of the MSS and the 4WD control module (GEM). Check all circuits for opens and shorts to power or ground.
Possible Causes
^ Mode select switch (MSS)
^ Circuit 465 (WH/LB)
^ Circuit 780 (DB)
^ 4WD control module (GEM)