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Home >> Chevrolet >> 1999 >> Blazer 4D Utility, 4WD, Automatic >> Repair and Diagnosis >> Transmission >> Transfer Case >> Transfer Case - Diagnosis - New Venture 233 (SELECTABLE 4WD) >> Diagnostic Tests >> DTC 3: TCCM Motor Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Did you perform Diagnostic System Check - Transfer Case? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK .
  2. Turn ignition on, with engine off. Backprobe and measure battery positive voltage (CKT 1640) at the transfer case shift control module. Does the voltage measure about battery voltage? If yes, go to step  6. If no, go to next step.
  3. Inspect the ATC Fuse 20A. Is fuse blown? If yes, go to step  5. If no, go to next step.
  4. Repair battery positive voltage circuit (CKT 1640) for an open or high resistance. After repairs, go to step  11.
  5. Repair battery positive voltage circuit (CKT 1640) for a short to voltage or short to ground. Replace ATC fuse. After replacing fuse, go to step  11.
  6. Connect a test light from the battery positive voltage circuit (CKT 1640) to the ground circuit at the transfer case shift control module. Does the test light illuminate? If yes, go to step  8. If no, go to next step.
  7. Repair the ground circuit for an open or high resistance. After repairs, go to step  11.
  8. Backprobe and measure voltage at the transfer case shift control module between the transfer case motor control "A" circuit and transfer case motor control "B" circuit. Press the 4HI then 4LO on the shift control switch. The DVOM should read +12V in one direction and -12V in the other direction. Does the voltage measure as specified? If yes, go to next step. If no, go to step  10.
  9. Check for open or high resistance in the transfer case motor control "A" or "B" circuits. Are circuits okay? If yes, replace transfer case encoder motor. If no, go to step  11.
  10. Replace transfer case shift control module. After replacing module, go to next step.
  11. Clear all DTCs from memory. Operate vehicle while pressing each of the buttons on the transfer case shift control switch. Does the DTC reset? If yes, go to step  2. If no, system is okay.
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