4WD will not engage.

[m610]

I'm finally getting around to fixing some of the things that haven't worked since I bought my Tahoe, and I'm actually having some success. One thing I'm still having a little trouble with is switching from 2WD to either 40-Hi or 4-Lo. The switch had been busted and I recently replaced it, and now at least something is happening. When I select 4-Hi the light flashes but never stops. When I select 4-Lo I hear something under the truck engage/move, but the light just keeps blinking. When I select 2WD again I hear that something underneath move again and the lights stop blinking and my Tahoe drives normally.

It seems I have the electrical part taken care of. Where do I look next?

(1996 Tahoe, base, 4-door, 4WD, 315k miles.)

Thanks in advance,
Mike

 

[PNW NBS Z71]

Don't know if you got this fixed but I would suspect the encoder motor having a problem.

Either this: https://www.rockauto.com/en/moreinfo.php?pk=926457&cc=1061356&pt=10456&jsn=1018

Or this: https://www.rockauto.com/en/moreinfo.php?pk=10378352&cc=1061356&pt=10456&jsn=1023

Don't just assume that it is the part when it could be wiring to it. Also, check all grounds related to that wiring.

Best source I have found for help with diagrams/pics/wiring schematics/diagnostic procedures is ALLDATAdiy.com

Same info supplied and used in shops across the country.

 

[m610]

I finally looked into this again. Trying to engage 4WD blows the 4WD fuse, #22 I believe, in the oddly named "convenience center."