Online Manual Jeep > Jeep Cherokee > Jeep Cherokee (XJ) > 1993 > LOCKING HUBS - COMMAND-TRAC & SELEC-TRAC

1993 Jeep Cherokee

1993 Drive Axles - Locking Hubs - Command-Trac & Selec-Trac Cherokee, Grand Cherokee, Grand Wagoneer, Wrangler


The Command-Trac locking hub is used on Wrangler 4WD. This system can be shifted between 2WD and 4WD high range, from inside the vehicle, while vehicle is moving. Command-Trac utilizes a vacuum operated shift motor to engage or disengage front drive axle shaft. Vehicle speed must be reduced to 2-3 MPH to shift into or out of 4WD low range. See Fig. 1.

Check Valve


Fig. 1: Command-Trac Vacuum Control System Courtesy of Chrysler Corp.

Selec-Trac locking hub is used on 4WD Cherokee. Selec-Trac utilizes a non-disconnect front axle. Engagement of 2WD or 4WD is accomplished at transfer case by means of mechanical shift linkage. System allows full or part time 4WD. Selec-Trac can be shifted into 2WD or 4WD modes from inside the vehicle at any speed.

NOTE: Grand Cherokee & Grand Wagoneer utilize Quadra-Trac full time 4WD system and DO NOT use Command-Trac or Selec-Trac 4WD system.



Place mode select switch in 4WD position while driving

vehicle 2-3 MPH (Command-Trac). Axle shift should be accompanied by a ratcheting sound followed by an audible mechanical engagement. Transfer case should shift after axle shifts, accompanied by hissing sound from mode selector switch.


  1. Place mode select switch in 2WD position. Transfer case
    should shift to 2WD and not allow shifting into 4WD or LO range. Axle
    should shift after transfer case shifts.

  2. To determine if front axle has completed a shift out of
    4WD into 2WD, position mode select switch back to 4WD position while
    operating vehicle at slow speed. If vehicle shifts into 2WD, axle will
    ratchet. If shift is not completed, transfer case will shift into 4WD
    and hissing sound will come from mode select switch.



  1. Raise and support vehicle. Remove vacuum harness from
    front axle shift motor. Apply 15 in. Hg to front port of shift motor.
    See Fig. 2. Rotate left front wheel to disengage axle (2WD operation).

  2. Replace shift motor if it does not hold vacuum for at
    least 30 seconds. If shift motor holds vacuum, disconnect vacuum pump
    from front port, Connect vacuum pump to shift motor rear port. See
    Fig. 2. Apply 15 in. Hg to shift motor.

  3. Replace shift motor if it does not hold vacuum for at
    least 30 seconds. While vacuum is applied to shift motor rear port,
    rotate left front wheel to ensure axle shafts are engaged (4WD
    operation). If axle shafts are engaged, shift motor and linkage are

  4. Indicator light switch is a mechanically mounted in shift
    motor housing. Axles must be completely engaged for shift motor shaft
    to actuate switch. If 4WD operation is engaged and indicator light on
    instrument panel illuminates, shift motor is operating properly. If
    not, check indicator light switch and bulb.


Fig. 2: Removing Shift Motor & Housing Courtesy of Chrysler Corp.




  1. Raise and support vehicle. Place a drain pan under shift
    assembly. Disconnect vacuum harness. Disconnect indicator light switch
    harness. Remove mounting bolts. Remove the shift motor assembly. See
    Fig. 2.

  2. Mark shift fork and housing for reassembly. Remove shift
    fork and motor snap rings. Remove shift motor from housing.


Install NEW "O" ring on motor shaft. Assemble shift motor shift fork onto shaft. Position motor and housing on axle. Add axle oil to shift motor housing. Install shift fork in shift collar and install mounting bolts. Connect vacuum harnesses. Connect indicator light switch harness.