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k2500 not shifting - electrical issues?

Discussion in 'Chevy C/K Truck Forum' started by carl s., May 10, 2009.

  1. carl s.

    carl s. New Member

    My 97 K2500 (6.5 dieslel) has been having some odd problems lately. A few weeks ago I went to pick up a trailer from a friend. The car drove fine on the way over. On the way back as we got onto the freeway we found it was not shifting out of 1st. Even manually shifting into 2nd or 3rd would not do anything. We hit the hazards to limp on the shoulder to the next exit - when the hazards were turned on, the gauge cluster flipped out. the tach and speedo bounced around, the gauge lights flickered and the engine actually started to run rough.

    We pulled off into a gas station and checked the trans fluid - it was full. we pulled the combination meter relay and the hazards fuse. We also unplugged the trailer connection. After all that the truck still would not shift out of first.

    The next thing we tried was driving it in reverse, putting it into 4H and 4L which didn't do anything. The last thing we tried was turning the truck off and on. Of course it wouldn't start. absolutely nothing, not even a click. There was a weird buzzing sound, like the door chime module or seatbelt module wasn't getting full power. but that was it.

    We then disconnected the battery, and clipped the wires for the electronic brake controller (which is what we were suspicious of due to its poor installation and the fact that the trailer had electronic brakes and the problem only happened once the trailer was connected). Once this was done the truck fired right up and shifted fine. It worked perfectly for the next week.

    Then this weekend I went to pick up a different trailer. About 20 mins of driving with that trailer the problem came back. The first clue was the tach was bouncing and settling on 0 rpm's while driving. then it stopped shifting again. We pulled over, found some wiring left over from the brake controller, removed it and it seemed to be ok. A little later the problem came back but this time the truck got stuck in 2nd instead of first. We parked and messed around with the wiring for a long time. When we started it, it ran fine and shifted fine - we hadn't really changed anything. We drove some more but then the problem came back, we were about 4 miles from a parts store so we limped it along - as we got closer the car lost more and more power and the gauge lights got very dim - almost like a dying alternator. we pulled the alt in the parking lot and had it tested - it was fine. we tried starting it again and it drove fine, shifted and everything - the only thing was we were missing the gauge cluster lights.

    Thats where it is now. It seems like it must be a grounding issue to me. any other ideas?
     
  2. Athanatos

    Athanatos New Member

    if you got electronic transfer case selector try the following



    MITCHELL 1 ARTICLE - 1997 TRANSFER CASES GM Corp. NV 243 Electronic Controls (Selectable 4WD)CLEARING DIAGNOSTIC TROUBLE CODES

    NOTE: DTCs will not be cleared if 20-amp T-case fuse is not removed for at least 30 seconds.
    Turn ignition off. Remove T-CASE (20-amp) fuse from fuse block. Wait at least 40 seconds and reinstall fuse. Cycle ignition on and off 5 times. All DTCs will be cleared from TCCM memory.
    TESTING

    TRANSFER CASE FUNCTIONAL TEST


    1. Place transmission is Park position. Turn ignition off and wait at least 6 seconds. Turn ignition to run position (engine off) and watch 3 shift select buttons. If all 3 shift select buttons blink once, go to next step. If all 3 buttons do not blink once, see step 2) in FUNCTIONAL TEST FAILED test.
    2. During step 1), if one button remained lit to indicate transfer case shift position, go to next step. If one button did not stay lit, see step 4) in FUNCTIONAL TEST FAILED test.
    3. Shift transfer case to 4HI, to 2HI, then back to 4HI. If transfer case mode shifts between 4HI and 2HI, go to next step. If transfer case mode does not shift between 4HI and 2HI, see step 6) in FUNCTIONAL TEST FAILED test.
    4. Apply parking brake. Place transmission in Park (A/T) or in 1st gear (M/T). Turn ignition to run position (engine off). Place transfer case in 4HI position. Pressure 4LO shift select button. If 4LO shift select button blinks for 30 seconds then stops when 4HI button illuminates, go to next step. If button blinking does not respond as indicated, see step 7) in FUNCTIONAL TEST FAILED test.
    5. Place ignition in run position (engine off). Shift transfer case to 4HI position and press 4LO shift select button while noting blinking. Place transmission in Neutral (A/T) or push clutch to floor (M/T). If 4LO shift select button stops blinking and stays lit when transmission is shifted as indicated, go to next step. If 4LO button does not respond as indicated, see step 7) in FUNCTIONAL TEST FAILED test.
    6. Press transfer case 2HI shift select button and shift transfer case to 2HI position. Place transmission in Park (A/T) or in 1st gear (M/T). Turn ignition off. Using a jumper wire, ground DLC pin No. 13. See WIRING DIAGRAMS . Turn ignition to run position (engine off). If all 3 shift select buttons blink once then stay off, test is complete, system is functioning normally. If all 3 shift select buttons do not respond as indicated, see step 8) in FUNCTIONAL TEST FAILED test.
    FUNCTIONAL TEST FAILED


    1. If any of the 3 shift select buttons blinked once, go to next step. If any button did not blink once, see ALL SHIFT SELECT BUTTONS DO NOT LIGHT test.
    2. If one shift select button stayed lit to indicate transfer case shift position, go to next step. If one button did not stay lit to indicate position, go to step 4).
    3. If transfer case mode shifts between 4HI and 2HI, go to next step. If transfer case mode does not shift between 4HI and 2HI, see REDUCED OR NO MODE & RANGE SHIFT OPERATION test.
    4. Turn ignition to run position (engine off). Place transmission in Neutral position. Push vehicle forward about 5 feet. If transfer case mode shifts between 4HI and 2HI, perform diagnosis of transfer case mechanical components. See TRANSFER CASE OVERHAUL NV-243 article in the POWERTRAIN section.
    5. If more than one shift select button stays lit, see MORE THAN ONE SHIFT SELECT BUTTON REMAINS LIT test. If more than one shift select button does not stay lit, see REDUCED OR NO MODE & RANGE SHIFT OPERATION test.
    6. Set parking brake. Place transmission in Park (A/T) or 1st gear (M/T). Turn ignition to run position (engine off). Pressure 4LO transfer case shift select button. If 4LO button blinks for 30 seconds, go to next step. If 4LO button does not blink for 30 seconds, to go step 8).
    7. With ignition in run position (engine off), press 4LO shift select button and note blinking. Place transmission in Neutral (A/T) or depress clutch pedal (M/T). If 4LO shift select button stops blinking and stays lit when transmission is shifted as above, see PERFORM A DIAGNOSTIC ON TCCM . If 4LO shift select button does not react as indicated, see REDUCED OR NO MODE & RANGE SHIFT OPERATION test.
    8. If, following steps 6) and/or 7), transfer case range shifts to 4LO, see ALL SHIFT SELECT BUTTONS REMAIN LIT test. If transfer case range does not shift to 4LO, see REDUCED OR NO MODE & RANGE SHIFT OPERATION test.


    if you get to step 8 in the failed functional tests you will need to check the harness for shorts and connectors are ok, if they are you will need specialized diagnostic equipment to check TCCM communications with the computer



    now also check if you can switch between 2wd and 4wd if not then you need to change the actuator motor on the front axle

    here's how to diagnose that

    MITCHELL 1 ARTICLE - 1997 TRANSFER CASES General Motors Corp. Borg-Warner 44-01 & 44-70 Diagnosis & Overhaul4WD Will Not Engage


    1. Test power to transfer case switch. With ignition on, connect test light to ground and backprobe Brown wire terminal at transfer case switch connector. Test light should light. If so, proceed to next step. If not, inspect 25-amp 4WD fuse in fuse block. If fuse is okay, attach test light to ground and backprobe Pink/White terminal at convenience center. Test light should light. If so, repair open in Brown wire between convenience center and transfer case switch. If not, repair open in Pink/White wire between convenience center and 4WD fuse in fuse block.
    2. Test transfer case switch. With transfer case shift selector in 4WD position and ignition on, attach test light to ground and backprobe Light Blue wire terminal at transfer case switch. Test light should light. If so, proceed to next step. If not, replace transfer case switch. NOTE: Remainder of transfer case electronic testing and diagnosis is performed with transfer case gear selector in 4WD position and ignition on.
    3. Test front axle solenoid power circuit. Attach test light to ground and backprobe Light Blue wire terminal of disconnected front axle solenoid. Test light should light. If so, proceed to next step. If not, repair open in Light Blue wire between front axle solenoid and transfer case switch.
    4. Test front axle solenoid. Attach test light between Light Blue wire terminal and Black wire terminal of connected front axle solenoid. If test light comes on, replace front axle solenoid and proceed to next step. If test light does not come on, repair open in Black wire between front axle solenoid and ground. If No opens in circuit are found, replace transfer case relay.
     
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