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HELP !! No 4X4 in my Avy !!!

Discussion in 'Chevy Trucks' started by Superior L & L, Dec 3, 2008.

  1. Superior L & L

    Superior L & L PlowSite Veteran
    from MI
    Messages: 3,039

    I was plowing earlier this week and I lost my 4x4 in my 2004 1500 Avalanche. (i know i should not plow with 1500). I checked both the electric engage motors and they are activating but no 4x4. The weird thing is it will work (with some clinking) in 4 low but not 4 high. Our automotive handy man thought it could be electrical since it has 4 low but we are stumped.

    Also last year we had some noise in the front diff.

    Please help me it sucks plowing in 2x4 or even worse the back up truck!
     
  2. fyerfytr

    fyerfytr Junior Member
    from Iowa
    Messages: 27

    Does the 4x4 indicator light up either in 4lo or 4hi?
     
  3. Superior L & L

    Superior L & L PlowSite Veteran
    from MI
    Messages: 3,039

    Yep in the cab the light lights up for 4 high and 4 low
     
  4. fyerfytr

    fyerfytr Junior Member
    from Iowa
    Messages: 27

    You might want to check the sending units on the transfer case. After replacing my transfer case with a rebuilt one, it would only work in 4lo. After replacing the sending units on the transfer case both 4hi and 4lo worked so it's worth looking into.
     
  5. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Could be the shift fork in the front axle. Ours went in our Trailblazer. It was aluminum. Did you pull the front axle actuator to confirm it is working?
     
  6. fyerfytr

    fyerfytr Junior Member
    from Iowa
    Messages: 27

    Thats the other thing I was thinking was the shift fork but I believe it's in the transfer case.
     
  7. MLLC

    MLLC Member
    from MA
    Messages: 49

    on my old 1500 it was the encoder motor for the t-case. but mine had autotrac 4x4
     
  8. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    There's a shift fork in the front axle to engage the passenger side shaft.
     
  9. Superior L & L

    Superior L & L PlowSite Veteran
    from MI
    Messages: 3,039

    Sending unit may be the ticket.


    Any thoughts b & b
     
  10. NBI Lawn

    NBI Lawn PlowSite.com Addict
    Messages: 1,797

    In my Tahoe the front actuator went bad, the 4x4 light would just flash though. I got under the truck, hit it a few times lightly with a hammer and it worked untill I sold it :)

    I believe I just saw them in a summit catalog for like $80
     
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Does it work in the "auto" position? In other words can you feel the front tires pulling if you launch it hard while in the auto position?

    And your positive they pull in 4 low as well? Or your simply stating that it works in 4 low because the T-case is going into low range?
     
  12. Superior L & L

    Superior L & L PlowSite Veteran
    from MI
    Messages: 3,039

    We put it up on jack stands and in 4 high the front wheels did not turn when engaged but in 4 low the front wheels would turn
     
  13. Superior L & L

    Superior L & L PlowSite Veteran
    from MI
    Messages: 3,039

    I replaced the actuator motor last year also :cry:
     
  14. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    What about the front drive shaft? Did it turn in 4 Hi with it in gear and running?




    The actuators can make noise and sound like they're engaging but not actually do so. But in your case if it works in low, it should work in Hi as well so I wouldn't suspect the actuator. So I'd be looking for a switch or encoder motor issue first.
     
  15. ght1098

    ght1098 Member
    Messages: 86

    Have you been plowing in 4hi or auto? Might have ruined the clutches in the transfer case.
     
  16. Superior L & L

    Superior L & L PlowSite Veteran
    from MI
    Messages: 3,039

    I plow in 4 hi
     
  17. Superior L & L

    Superior L & L PlowSite Veteran
    from MI
    Messages: 3,039

    Yep the drive shaft does turn in 4 hi.
     
  18. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Then I'd be likely to suspect a 4x4 switch failure and not a T-case, encoder motor, or axle actuator.
     
  19. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    I tried to post this morning but my DSL died. Anyhow....
    You said Lo Range works, and your front driveshaft is turning in 4 HI. I presume you meant the driveshaft is turning on it's own when the truck was up on jackstands and in gear with the engine running.. I would still say your problem is in the front axle. When the axle shift fork went in our Trailblazer, the symptoms were very similiar to what you are describing. Sometimes if felt like it would work for a bit, then not. And Lo Range still worked. Also the dash would light up correctly.
    You said the front driveshaft turns in 4 HI. If the xfrer case is in 4HI (with the vehicle not moving) you should not be able to turn the front driveshaft by hand at all.

    Try this test with at least one front tire off the ground. You don't need the engine running, just the key on. Try spinning the front shaft in all Xfer case positions. It should spin easy in 2 HI. No spin in 4 HI or 4 LO. 4 Auto it may spin, with some resistance. If this seems right, I would confirm operation of the front axle shift motor. It should be easy to get off and confirm operation. Pull it off and change from 2 Hi to any other position. You should see the actuator extend, then retract for 2 HI. Also, the front axle sensor is in the actuator. So if the actuator works, the truck thinks you are in 4WD.
    If all of these things work properly, you very likely have a broken axle shift fork. Or something else like a shaft or differential component in the front axle is broken. Replacing the fork will probably require removing the pass side CV shaft tearing down the pass side of the axle. You could probably pull the diff cover and confirm the pass side axle is not connected to the diff gears before tackling that.
     
    Last edited: Dec 6, 2008
  20. mikeauto1

    mikeauto1 Junior Member
    from nh
    Messages: 6

    no 4 wheel drive

    i would put a scanner on the vehicle to seee if the any code in computer anywhere. if tyou have a bad encoder motor it would trip a code. then there is a mode in the scanner where you can command the transfer case to go through all the functions, try that if you can get a scanner before replacing any more parts.