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Electronic Shift Functional Test

  1. Place hublocks in AUTO position. Start engine and let idle. Apply and hold brake pedal. Place transmission in Neutral (A/T), or depress and hold clutch pedal (M/T). Place mode switch in 2WD position. Observe 4X4 and LOW RANGE indicator lights. If both indicator lights are not illuminated, go to step  3. If one or both indicator lights are illuminated, go to next step.
  2. Back up vehicle 10 feet to relieve driveline windup. Drive forward 10 feet. Depress and hold brake pedal. Place transmission in Neutral (A/T), or depress and hold clutch pedal (M/T). Hold these conditions for 20 seconds. Perform several tight turns on a hard surface. Check for driveline windup and tire scuff. If windup and tire scuff is present, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, problem in is transfer case. See NV271 & NV273 TRANSFER CASE OVERHAUL article. If 4X4 indicator light is illuminated, perform test TEST D  under DIAGNOSTIC TESTS. If LOW RANGE indicator is illuminated, perform TEST E  under DIAGNOSTIC TESTS.
  3. Turn ignition off. Turn ignition on and check if 4X4 and LOW RANGE indicator lights illuminate momentarily as a bulb check, and then turn off. If indicator lights illuminated and then turned off, go to next step. If indicator lights did not illuminate, or remain illuminated, problem is in instrument cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
  4. With ignition on, place mode switch in 4X4 HIGH position. Listen for relay clicks and shift motor operation. Wait 20 seconds as system attempts to engage 4X4 HIGH up to 5 times. If 4X4 indicator light is illuminated, go to step  6. If 4X4 indicator light is not illuminated, go to next step.
  5. Drive vehicle for 20 seconds at more than 5 MPH. Stop vehicle. If 4X4 indicator light is illuminated, go to next step. If 4X4 indicator light is not illuminated, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform TEST B  under DIAGNOSTIC TESTS.
  6. Drive vehicle for 2 minutes at more than 10 MPH. Check for driveline windup and tire scuff. If windup and tire scuff is not present, 4X4 HIGH did not mechanically engage. Retrieve DTCS. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, go to next step.
  7. Raise and support front of vehicle so wheels are off the ground. Rotate left front wheel while watching left axle shaft and universal joint. Repeat on right side. If both front axle shafts rotate, go to next step. If axle shafts did not rotate, perform TEST C  under DIAGNOSTIC TESTS.
  8. Rotate front drive shaft. If either front axle shaft rotates, perform TEST B  under DIAGNOSTIC TESTS. If either front axle does not rotate, problem is in front differential or axle. See appropriate article in DRIVE AXLES in lemon-25® ENGINE, CLUTCHES & DRIVE AXLES manual for DOMESTIC VEHICLES. Repair as necessary.
  9. Drive vehicle forward at more than 5 MPH and place mode switch in 4X4 LOW. Observe indicator lights. Place mode switch in 4X4 HIGH. Stop vehicle and apply parking brake. On A/T models, place transmission in Park and release brake. On M/T models, place transmission in Neutral and release clutch pedal. On all models, if LOW RANGE indicator light is off, go to next step. If LOW RANGE indicator light is illuminated, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform TEST C  under DIAGNOSTIC TESTS.
  10. Place mode switch in 4X4 LOW. Depress and hold brake pedal. If LOW RANGE indicator light is off, go to next step. If LOW RANGE indicator light is illuminated, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform TEST C  under DIAGNOSTIC TESTS.
  11. Place transmission in Neutral (A/T), or depress and hold clutch pedal (M/T). Place mode switch in 4X4 LOW. Listen for relay clicks and shift motor operation. Wait 20 seconds as system attempts to engage 4X4 LOW up to 5 times. If LOW RANGE indicator light is illuminated, go to step  13. If LOW RANGE indicator light is not illuminated, go to next step.
  12. Back up vehicle 10 feet to relieve driveline windup. Drive forward 10 feet. Depress and hold brake pedal. Place transmission in Neutral (A/T), or depress and hold clutch pedal (M/T). Hold these conditions for 20 seconds. If LOW RANGE indicator light is illuminated, go to next step. If LOW RANGE indicator light is not illuminated, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform TEST C  under DIAGNOSTIC TESTS.
  13. Place mode switch in 4X4 LOW. Perform several tight turns on a hard surface. Check for driveline windup, tire scuff and reduced speed. If windup, tire scuff and reduced speed is present, go to next step. If windup, tire scuff and reduced speed is not present, 4X4 LOW did not mechanically engage. Retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform TEST C  under DIAGNOSTIC TESTS.
  14. Drive vehicle forward at more than 5 MPH and place mode switch in 4X4 HIGH. Observe indicator lights. Place mode switch in 4X4 LOW. Stop vehicle and apply parking brake. On A/T models, place transmission in Park and release brake. On M/T models, place transmission in Neutral and release clutch pedal. If LOW RANGE indicator light is illuminated, go to next step. If LOW RANGE indicator is not illuminated, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform test TEST C  under DIAGNOSTIC TESTS.
  15. Place mode switch in 4X4 HIGH. Depress and hold brake pedal. If LOW RANGE indicator is illuminated, go to next step. If LOW RANGE indicator is not illuminated, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform TEST C  under DIAGNOSTIC TESTS.
  16. Depress and hold brake pedal. Place transmission in Neutral (A/T), or depress and hold clutch pedal (M/T). Place mode switch in 4X4 LOW. Listen for relay clicks and shift motor operation. Wait 20 seconds as system attempts to engage 4X4 HIGH up to 5 times. If LOW RANGE indicator illuminates, go to next step. If LOW RANGE indicator light does not illuminate, go to step  18.
  17. Place transmission in Neutral (A/T), or depress and hold clutch pedal (M/T). Hold this condition for 20 seconds. If LOW RANGE indicator light is not illuminated, go to next step. If LOW RANGE indicator light is illuminated, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform TEST C  under DIAGNOSTIC TESTS.
  18. Drive vehicle in Reverse for 10 feet to relieve driveline windup. Stop vehicle. Place mode switch in 4X4 LOW. Drive forward and place mode switch in 4X4 HIGH and perform several tight turns on a hard surface. If 4X4 HIGH engaged and vehicle speed increased, go to next step. If 4X4 HIGH did not engage and vehicle speed did not increase, 4X4 LOW is mechanically bound or locked. Problem in is transfer case. See NV271 & NV273 TRANSFER CASE OVERHAUL article.
  19. Stop vehicle. Place mode switch in 2WD position. Wait 20 seconds. Listen for relay clicks and shift motor operation. If 4X4 HIGH and LOW RANGE indicator lights are not illuminated, go to step  21. If indicator lights are illuminated, go to next step.
  20. Drive vehicle forward at 5 MPH for 20 seconds. Stop vehicle. If 4X4 HIGH and LOW RANGE indicator lights are not illuminated, go to next step. If indicator lights are illuminated, retrieve DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, perform TEST B  under DIAGNOSTIC TESTS.
  21. Raise and support front of vehicle so wheels are off the ground. Rotate left front wheel while watching left axle shaft and universal joint. Repeat on right side. If both front axle shafts rotate, perform TEST C  under DIAGNOSTIC TESTS. If axle shafts did not rotate, go to next step.
  22. Apply parking brake. Attempt to rotate front drive shaft. If front drive shaft rotates, go to next step. If front drive shaft does not rotate, problem is in transfer case. See NV271 & NV273 TRANSFER CASE OVERHAUL article.
  23. Place both hublocks in LOCK position. Rotate left front wheel while watching left axle shaft and universal joint. Repeat on right side. If both front axle shafts rotate, go to next step. If axle shafts do not rotate, replace hublock.
  24. Place both hublocks in AUTO position. Rotate left front wheel while watching left axle shaft and universal joint. Repeat on right side. If either front axle shaft rotates, replace hublock. If both axle shafts do not rotate, transfer case is operating normally.
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