Component Testing

A16 Transfer Case Motor (Transfer Case Range Actuator)

1. Remove the A16 transfer case motor from transfer case. Using a paint pen or marker, place indexing marks on the A16 transfer case motor drive gear and the mounting surface of the A16 transfer case motor.
NOTE:
• When test probing harness terminals, it is imperative to use the proper test probe from the most current version of the J 35616  GM-Approved Terminal Test Kit. Use of an improper test probe may deform the terminal, resulting in intermittent open conditions.
• Testing for steps 2-11 is performed on the A16 transfer case motor harness connector using the PU probes J 35616-5.
2. Attach the red lead from one of the EL-49741  harnesses to the battery positive voltage terminal of the A16 transfer case motor, terminal B.
3. Attach the black lead from this same jumper harness to the transfer case lock solenoid control terminal of the A16 transfer case motor, terminal C.
4. Attach a 9-volt battery to this harness (not included). You should hear the A16 transfer case motor unlock.
   • If you do NOT hear the A16 transfer case motor unlock 

     Replace the A16 transfer case motor and perform the Range Actuator Learn procedure. Refer to Transfer Case Two/Four Wheel Drive Actuator Replacement , and Transfer Case High/Low Clutch Reset .

   • If you DO hear the A16 transfer case motor unlock 
5. Attach the red lead from the other EL-49741  jumper harness to the transfer case motor clockwise control circuit of the A16 transfer case motor, terminal A.
6. Attach the black lead from this same jumper harness to the transfer case motor counter-clockwise control circuit of the A16 transfer case motor, terminal D.
7. Touch the battery terminals of the 9-volt battery to the battery terminals of the jumper harness. This should rotate the A16 transfer case motor drive gear in either a clockwise or counter-clockwise rotation depending on battery orientation.
   • If the A16 transfer case motor drive gear does not perform as described 

     Replace the A16 transfer case motor and perform the Range Actuator Learn Procedure. Refer to Transfer Case Two/Four Wheel Drive Actuator Replacement , and Transfer Case High/Low Clutch Reset .

   • If The A16 transfer case motor drive gear performs as described 
8. Verify 0.3-40 Ω resistance between the transfer case motor clockwise control circuit of the A16 transfer case motor, terminal A and the transfer case motor counter-clockwise control circuit of the A16 transfer case motor, terminal D.
   • If NOT 0.3-40 Ω 

     Replace the A16 transfer case motor and perform the Range Actuator Learn Procedure. Refer to Transfer Case Two/Four Wheel Drive Actuator Replacement , and Transfer Case High/Low Clutch Reset .

   • If 0.3-40 Ω 
9. Test for infinite resistance between the following circuits and the A16 transfer case motor case:
   • Transfer case motor clockwise control circuit of the A16 transfer case motor, terminal A
   • Transfer case motor counter-clockwise control circuit of the A16 transfer case motor, terminal D
   • If less than infinite resistance 

     Replace the A16 transfer case motor and perform the Range Actuator Learn Procedure. Refer to Transfer Case Two/Four Wheel Drive Actuator Replacement , and Transfer Case High/Low Clutch Reset .

   • If infinite resistance 
10. Test for infinite resistance between the transfer case motor clockwise control circuit of the A16 transfer case motor, terminal A and all other terminals on the A16 transfer case motor harness except the transfer case motor counter-clockwise control circuit of the A16 Transfer Case Motor, terminal D.
    • If less than infinite resistance 

      Replace the A16 transfer case motor and perform the Range Actuator Learn Procedure. Refer to Transfer Case Two/Four Wheel Drive Actuator Replacement , and Transfer Case High/Low Clutch Reset .

    • If infinite resistance 
11. Test for infinite resistance between the transfer case motor counter-clockwise control circuit of the A16 transfer case motor, terminal D. and all other terminals on the transfer case range actuator harness except the transfer case motor clockwise control circuit of the A16 transfer case motor, terminal A.
    • If less than infinite resistance 

      Replace the A16 transfer case motor and perform the Range Actuator Learn Procedure. Refer to Transfer Case Two/Four Wheel Drive Actuator Replacement , and Transfer Case High/Low Clutch Reset .

    • If infinite resistance 
12. A16 transfer case motor OK.
13. Inspect the transfer case shift detent lever shaft for a binding condition.
    • If binding 

      Remove the transfer case and repair the binding condition. Refer to Transfer Case Shudder or Binding .

    • If not binding 
14. Refer to Symptoms - Transfer Case , and Transfer Case Will Not Shift .