Four Wheel Drive

MARK RAGNOLI

MEMBER
GMC JIMMY

1999 GMC Jimmy 4x4 4.3L 180,000 miles.
When going from 2 wheel drive to 4 wheel drive any mode AWD, 4 High, 4 Low push swith on dash lights flash the returns to 2 wheel drive. Never transfers from 2 whee drve to 4 wheel drive.
Any thoughts?

4 Replies

CHEVY22

MECHANIC
1,375 POSTS

First check to see when you turn the key if all of the lights on the switch cycle you should see all yellow and one red if this is ok, open your door and try and switch in and out of 4x4 see if you hear the encoder motor under you whining and clicking into gear, if you dont hear anything or if you hear a whine and no clunk the encoder motor is bad if you hear nothing it may be the tccm let me know
jim

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Wednesday, October 10th, 2007 AT 10:25 PM

NENADV23

MEMBER
2 POSTS

Writing again just to add my address nenadv23@yahoo. Ca

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Thursday, October 25th, 2007 AT 8:10 PM

NENADV23

MEMBER
2 POSTS

I see my first message did not go but the secon did. Wanted to say I have similar problem with Jimmy 1999, 185,000km. When dushing the 4HI button nothing hapens, when pushing the 4LO button it works. The previous owner told me he was told that one (of the two) selenoid does not work. Please let me know if you find out what could be the problem. I'll do the same. Thanks Nenad

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Thursday, October 25th, 2007 AT 8:28 PM

CHEVY22

MECHANIC
1,375 POSTS

I would try the switch before I do anything on yours, they are failrly inexpensive and they go bad alot, start there and let me know what happens

ps this is mandatory on any 4x4 problem I work on, but I have spares in my tool box

jim

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