4 wheel drive not working

Tiny
FCSMILEK
  • MEMBER
  • 2004 HUMMER H2
  • V8
  • AWD
  • AUTOMATIC
  • 130,000 MILES
When trying to engage into either high lock or low lock, a message appears "service 4wd" and the H2 Hummer just stays in the regular all wheel drive mode. This started happening last winter and is consistant in cold weather when in MT. When I am in Houston this rarely happens, it usually will engage in either high or low lock. Someone told me the electrical actuator needs to be replaced with a pneumatic actuator. Thoughts?
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Thursday, December 18th, 2008 AT 7:12 PM

8 Replies

Tiny
BRIAN 1
  • MEMBER
Hello,

It sounds like the transfer case encoder is out, here are diagrams to help you change it out. Check out the diagrams (Below). Please let us know what happens.
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Thursday, December 18th, 2008 AT 7:39 PM
Tiny
DUFFER69
  • MEMBER
Thank you for this post I got a new encoder for $127.00 and all set! Thanks guys :)
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Monday, December 10th, 2018 AT 7:24 PM
Tiny
SEASON4U
  • MEMBER
  • 1996 HUMMER H2
Drive Train Axles Bearings problem
1996 Hummer H2 V8 All Wheel Drive Automatic

got stuck in snow, after 3rd or 4th time stuck heard something break then my gears would not work in all wheel drive, but will work in 4 wheel low and high. Could this be a CV joint?
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Monday, December 10th, 2018 AT 7:24 PM (Merged)
Tiny
DR LOOT
  • EXPERT
No! You broke something in the transfer case
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Monday, December 10th, 2018 AT 7:24 PM (Merged)
Tiny
H2ANDYOU
  • MEMBER
  • 2003 HUMMER H2
  • V8
  • 4WD
  • AUTOMATIC
  • 80,000 MILES
We I start the vehicle in the morning it idles fine, but when I put my foot on the brake and put it in Drive the vehicle won't Idle. Second problem. I put it in 4 wheel drive low and it will not come out, Tried everything, I hear and feel activity when I press the 4HI and the 4HI LOCK buttons but the lights only blink and won't go solid. Could it be the motor actuator on the transfer case? Thanks, Troy
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Monday, December 10th, 2018 AT 7:25 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Troy,

It sounds like the actuator may be the problem, but before replacing that, check to make sure it is receiving power when you switch from 4lo to 4hi.

As far as the idle, has the check engine light ever come on?
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Monday, December 10th, 2018 AT 7:25 PM (Merged)
Tiny
H2ANDYOU
  • MEMBER
Thanks for responding. I got it back into 4HI but as far as the idle. Yes the engine light has been on for a few months. I have a P0135 fault (bad oxygen sensor) but the idle problem has only been happening for a few days.

Thanks,
Troy
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Monday, December 10th, 2018 AT 7:25 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Channces are the O2 sensor wasn't working correctly at first, and now it has gone bad. If you remove it, check to see if it is carboned (black).

Let me know what you find.
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Monday, December 10th, 2018 AT 7:25 PM (Merged)

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