# 1997 chevy 4wd pickup wont go into 4wd!

**URL:** <https://community.cartalk.com/t/1997-chevy-4wd-pickup-wont-go-into-4wd/61003>\
**Category:** Maintenance/Repairs\
**Tags:** chevrolet\
**Created:** [February 7, 2011, 3:58am UTC](https://community.cartalk.com/t/1997-chevy-4wd-pickup-wont-go-into-4wd/61003 "2011-02-07T03:58:09Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![lwhenshawiii](https://avatars.discourse-cdn.com/v4/letter/l/cab0a1/32.png) [@lwhenshawiii](https://community.cartalk.com/u/lwhenshawiii)\
**Post date:** [February 7, 2011, 3:58am UTC](https://community.cartalk.com/t/1997-chevy-4wd-pickup-wont-go-into-4wd/61003/1 "2011-02-07T03:58:09Z")

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I HAVE SHIFT ON THE FLY 4WD IN MY 1997 PU. THE 4HI SHIFTER JUST FLASHES WHEN PUSHED AND WONT GO INTO 4 HI 4WD.WHAT TECHNIQUES DO I USE TO TROUBLE SHOOT AND REPAIR THIS PROBLEM!!!

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**Author:** ![edb1961](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/edb1961/32/122_2.png) [@edb1961](https://community.cartalk.com/u/edb1961)\
**Post date:** [February 7, 2011, 4:44am UTC](https://community.cartalk.com/t/1997-chevy-4wd-pickup-wont-go-into-4wd/61003/2 "2011-02-07T04:44:28Z")

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Autotrac (Auto 4wd) or Controltrac? Is the transfer case engaging and/or the front hubs?

According to a GM tech I know, if 4wd is not engaged on a regular basis the Transfer Case Control Module (TCCM) will lock up. To reboot the TCCM, disconnect the wiring harness at the TCCM or disconnect the battery.

Next check the vacuum lines, I found a few rotten ones on my 2000 Blazer last year. When the 4wd quit completely on the Blazer it turned out to be the vacuum switch that controls the vacuum actuator that engages the front axles. Scroll about 1/3 of the way down the link to see the switch.

[http://www.automotiveforums.com/vbulletin/t572914.html](http://www.automotiveforums.com/vbulletin/t572914.html)

Here’s another useful link

> **['03 Chevy Blazer - where's my 4 wheel drive? (UPDATED) - kylestubbins.com](https://www.kylestubbins.com/03-chevy-blazer-wheres-my-4-wheel-drive-updated/)**
>
> Problems of corrosion on the TCCM wires on my 2003 Chevy Blazer 4 Wheel Drive.

Good luck and please turn off the caps,

Ed B.