Have the vehicle plugged into a diagnostic computer it should be showing a fault code !
Vehicle Does Not Shift Between 2WD & 4WD High Modes Properly
Possible causes: 4WD mode switch, 4WD clutch relay, contact plate sensors, T/C shift motor, transfer case and/or GEM. Go to TEST A under TESTING.
Vehicle Does Not Shift Between 4WD High To 4WD Low Properly,
Shifts Properly Between 2WD To 4WD High, 4WD High To 2WD
Possible causes: 4WD mode switch, vehicle speed sensor, BOO switch, transfer case, TR sensor and/or GEM. Go to TEST B under TESTING.
Front Axle Not Engaging Or Disengaging Properly
Possible causes: 4WD solenoid, 2WD solenoid, vacuum motor, vacuum lines, front differential and/or GEM. Go to TEST C under TESTING.
4WD LO &/Or 4WD HI Indicator Light Not Operating Properly
Possible causes: light bulb, TR sensor and/or GEM. Go to TEST D under TESTING.
4WD HI Does Not Engage At Speed Properly (Driveline Does Not
Synchronize Properly) But Does Engage At Rest
Possible causes: ESOF clutch relay, internal clutch, hub release spring and/or wiring harness. Go to TEST E under TESTING.
No Communication With GEM
Possible causes: Fuses, harness and/or GEM. Go to TEST F under TESTING.
Tuesday, April 28th, 2009 AT 4:40 PM