2005 GMC sierra 4wd problem

[melanie33]

My 2005 GMC sierra truck indicator came on saying service 4wd. When I try to change from 2wd to either 4wd hi or low it doesn't the light stays on 4wd hi even if the other buttons are pushed. If I start to drive it only kickes in 4wd hi if I accelerate while turning the wheel, if I coast while turning it doesn't it stays in 2wd even though the light stays lit on 4wd hi I can feel its not. Any suggestions on fixing this mess?

[Chris]

Take it in, there is a code to be diagnosed

[Tulsa Tom]

Agree that the OBDII code will hopefully tell the story. You will need 4WD to explore the Jemez this winter. I do miss living in Rio Rancho and having 10 billion acres of backyard to explore.

[Chris]

A standard scanner will not read that code

[Tulsa Tom]

A standard scanner will not read that code

What about a Tech-2 with a CAN interface? As long as you have the software? Thanks.... cause I was thinking of getting one for my 2007.

[Chris]

Yes a Tech 2 can read them with the CAN interface. I was looking into one for the Sierra, Rainier, and the G6. A CAN interface is needed for the G6

[Chris]

I misspoke, you do not need the CAN interface for your 07 classic, The GMT-900 needs it and anything else that has had a body change after 06

[Tulsa Tom]

Your description really fits a scenario for the dashboard 4WD switch being bad. I found a video about 4WD switch problems being a large percentage of the root cause of 4WD Service lights. It has the procedure for checking the impedance of the various switch positions. Might save you some $$$$. Just need a multimeter. I think it's worth a try before going to the dealership. You can find the video under you tube user "MAY03LT"

[Chris]

That issue was something about poor soldering

 

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