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Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 16035
Experience:  Have owned a repair shop for 25 yrs.
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I have a 1999 GMC Jimmy, 4.3, The 4X4 is not working, it goes

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I have a 1999 GMC Jimmy, 4.3, The 4X4 is not working, it goes into 2 wd when ever you start it, when you push the 4 h, 4 l or 4aw the service 4x4 lite comes on and the corasponding lite flashes, you can here the transfer case engage, and on a lift the front shaft is turning, there is vacume to the vac switch on the fire wall but it does not open (replaced) there is power to one side of the switch in all 4wd modes, vac applied to the valve under and battery seem to be operating, I have a code C0367 any help would be great


this may be a problem with thr front axle clutch solinoid


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Circuit Description
The front axle control circuit consists of a Front Drive Axle Clutch solenoid which is electronically controlled by the transfer case shift control module. This solenoid opens and closes a vacuum control valve allowing vacuum to apply and release a clutch pack inside the front axle housing. The transfer case shift control module determines whether or not the clutch pack has been applied or released based on a signal form the front axle switch mounted on the front axle housing assembly. The front axle is normally locked or engaged during AUTO 4WD, 4WD HI, and 4WD LO modes. The front axle is unlocked or disengaged only during 2 HI or neutral modes.

Conditions for Setting the DTC


  • The system will try to engage the front axle. If it can not engage the front axle, the system will not attempt it again during that ignition cycle.
  • The transfer case shift control module reads back the front axle output as a high voltage when a low voltage is expected.

Action Taken When the DTC Sets

  • All shifting for 4WD, AUTO 4WD, and 4WD LO modes will be disabled.
  • SERVICE indicator (4WD/AWD) lamp will be latched on for the remainder of the current ignition cycle.

Conditions for Clearing the DTC

  • The Transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists.
  • A history DTC will clear after 100 consecutive ignition cycle without a fault present.
  • History DTCs can be cleared using a scan tool.


Test Description
The number(s) below refer to the step number(s) on the diagnostic table.


  1. Tests the operation of the front axle switch.
  2. Tests the front axle control circuit for a short to voltage.
  3. Helps determine whether the short to voltage is due to a faulty transfer case shift control module or wiring.
icon_note_blank.gif Notes
icon_note_blank.gif Notes
Shift Mechanism Inspection
  1. Inspect the carrier connector for damaged splines and teeth. Replace as required. Inspect the shift fork for wear, scoring, and damage to the thrust surfaces. Replace as required.
  1. Inspect the differential sleeve and the inner output shaft for damaged splines and teeth. Replace as required.
  2. Inspect the damper spring for breakage. Replace as required.
  3. Inspect the differential actuator and the engagement switch for damage and frayed wiring.
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