Front Axle Shift Motor Test
- Raise and support vehicle. Remove vacuum harness from front axle shift motor. Apply 15 in. Hg to front port of shift motor. See Fig 1. Rotate right front wheel (or rear drive shaft on Selec-Trac) to disengage axle (2WD operation).
- Replace shift motor if it does not hold vacuum for at least 30 seconds. If shift motor holds vacuum, remove vacuum pump. Connect vacuum pump to shift motor rear port and cap indicator light switch port. See Fig 1. Apply 15 in. Hg to shift motor.
- Replace shift motor if it does not hold vacuum for at least 30 seconds. If shift motor holds vacuum, remove cap from indicator light switch port.
- If vacuum is present, shift motor is okay. If no vacuum is present, cap indicator light switch port and reapply 15 in. Hg to shift motor rear port. Rotate right front wheel to make sure axle shafts are engaged (4WD operation).
- Axles must be completely engaged to open indicator light switch port. If vacuum is now present at indicator light switch port, shift motor is okay. If not, replace shift motor or repair shifter mechanism.
Courtesy of CHRYSLER MOTORS.