4 wheel drive problems

[Jhohman]

Hello all,

Sorry if this has been posted before. I have a 2004 Tahoe Z71 with 190k on it. I started noticing that when I turn the truck on, it is in 4hi or 4lo. When I pushed the switch to put it back in 2hi, the switch would blink and then stay in either 4hi or lo. After multiple times it would finally go into 2hi then "service 4 wheel drive" would show up on the dash. After reading some forums and talking with others I found that the switch could be going bad, so I bought a new one and replaced it. The problem stopped for about 2 days or so and then same thing happened. This time when I pushed the switch to put it in 2hi and it went in 2hi fairly quick. It has been about 2 months since I have had a problem. Today I turn the truck on and the switch light is red and is in neutral. I pushed 2hi, 2hi lite up, then "service 4 wheel drive" shows up on the dash. I can put the truck in 4hi or lo and it is a hit or miss whether or not its a nice and smooth transition or clinking and not so smooth transition. I am not a mechanic by any means. I can get around with in reason, I normally do my own maintenance. I don't know all the acronyms so if you could put things into layman's terms that would be best. Thank you in advance for helping

 

[Jhohman]

UPDATE: Driving today and the lights on the 4 wheel drive switch have gone out. Now it just says service 4 wheel drive on the dash. Not sure where to go from here. Any ideas?

 

[Hitdog042]

UPDATE: Driving today and the lights on the 4 wheel drive switch have gone out. Now it just says service 4 wheel drive on the dash. Not sure where to go from here. Any ideas?

I had a similar issue and I just pulled the negative off the battery and waited 5 minutes to re set. Put it back on and all my 4wd lights came back on the switch and can use all modes again.

Not sure if it will work for you but it's worth a shot. My problem was no lights on switch and service 4wd. Replaced switch and it didn't work. Then did battery thing and voila.

 

[Jhohman]

The lights came back on the next day when I started the truck to go to work. Still every now and again I start the truck and it is in auto 4WD or in 4HI or LO.

Took the truck to a dealership(one that my buddy works at so I didn't get charged) had him hook up the Tech 2. I did not catch what code he said it was but he told me to replace the TCCM (Transfer Case Control Module). These vehicles are notorious for these things going out between 03-04 GM had a bad batch go out from what I was reading. Unhooking the battery seems like a pretty simple thing to do before I go drop money on a new TCCM. Found em for a couple hundred with a hundred core charge refurbished. Has anyone bought one of these? Should I buy new?

 

[mwkoenig]

confused

I have a 2005 Tahoe z71 with the service 4X4 on and Stability System disabled light on. I replaced the switch and the gear on the transfer case and nothing. What else can I do? I heard that someone reflashed the computer and it worked but that's a lot of money I don't have at this time.

 

[Hitdog042]

Try the battery reset. Couldn't hurt. Unplug negative. Wait 5 min. Reconnect. Worked for me.

 

[mwkoenig]

ok...ill let you know

 

[owlsarepretty105]

I'm new and I'm interested in this topic. Thank you!

 

[JMR 1964]

Hello,
I've recently bought a 2004 LT tahoe. When I turn it on, often times the transmission switch displays a new transmission setting- in example, I'm usually in 2wd. When I turn the truck on it will set in 4h, Auto 4wd, 4L. I replaced the TCCM, which helped one problem- I wasnt able to shift out of the selected gear, now it will shift back just finee, I'm able to shift back into 2 wd or any other configuration w/o a problem.
I believe the shift motor was changed prior to me purchasing the truck, so not sure if its that. Might not be an OEM part.
Any other thoughts as to why the truck is shifting when I turn it back on?
Thanks for any help. Bought the truck to pull a boat, and I like it very much.
Best regards,