4 Wheel Drive with mind of its own!?

[MedicatedMike]

well, I still havent had a chance to get the Transfer Case fluid changed or the new 4 wheel drive switch in the dash yet but with the newest turn of events, I feel I should ask for some advise before something more happens....

First off, all the lights in the switch light up when truck is started and everything in switch seems to work right, just the knob u actual grab onto, broke off not leaving much to grab onto. You can hold the broke off piece on their and it actually stays in place by itself for now.

It started acting up a little, meaning when we tried to switch from 2 wheel drive to All wheel drive for instance, it would light up the desired mode with a few flashes but then go back to the original mode and as far as we could tell, never changed modes physically, just the lights act like it wants to for a sec, and then gives up.

We decided to just leave it alone after getting it back in 2wd a few weeks back until I can get fluid and switch changed and then trouble shoot encoder motor most likey if still problems. WELL....now its going back and forth between 2wd and AWD randomly while driving....we aren't trying to make it switch, it does it all by itself when it feels like it.....

started off......try to switch....it wont. Now dont try to switch....it does by itself....LOL

Any ideas Roadie?

 

[Matt]

That behaviour sounds like it's the TCCM gone flaky, which is weird considering you have an 05. The 02's are normally the ones that go bad.

 

[The_Roadie]

Flaky switch first thought. Make sure it's in 2WD mode, then pull the fuse to the TCCM to keep it from trying to change. Since switches are cheap even at the dealer, just pry it out of the panel and swap it ASAP. Why are you putting it off? No local dealers? Then follow my normal advice about listening for the distinctive noises made by the front axle actuator and the encoder motor and you might be able to tell which of those two circuits has a problem.

 

[Voymom]

We had issues with our 4wd going out, hubby looked at the TCCM and wiggled a few wires, found a loose one and tightened it up, 4wd works just fine now!! So maybe a loose connection?

 

[navigator]

I say if the switch is visibly broken, it could be broken where you cannot see as well. I would change it quickly.

 

[MedicatedMike]

Well, already have another switch (but its out of a 06 and our TB is an 05) but just havent had time to install since it showed up this past week. With only 1 family vehicle and large family its very restrictive when i have time to work on the TB without it being needed half hour later.

Also I honestly didnt see how the switch itself could cause this weird behavior and was decently sure its an electrical or module problem most likely but I will get it switched out ASAP and report back. Might have to wait to thursday though.

I feel alot better that there is a deff easy fix with the fuse for TCCM if cant get straightened out in next few weeks since we need to take the TB all the way to South Carolina next month. (Im just afraid its not something real simple like the switch or fluid.)

Thanks for all the replies already and I will report back on the findings later this week.

 

[MedicatedMike]

*small update*

Swapped out the 4x4 switch tonight after she got home from work and at least it was encouraging! We havent had a chance to drive it enough to make sure it isnt going to change on its own any more but it does switch back and forth between 2WD and AWD at will like it should! I wasnt brave enough to try and shift in 4x4, lol. So crossing fingers it wont change on its own and it was just a flaky switch!

I do anything that requires a jack and stands at my brother in laws house as he has more tools and a garage. I was already planning on changing the oil on Thursday with the new AMSoil Sig series I got from Steve. Thanks Steve! So, Im just going to change the TC fluid with new Auto trak II at the same time. Also, if we have time, we will change the cat conv. and o2 sensor too as they should be here tomorrow! Go rockauto with fast delivery!!

 

[EAnton781]

My 2002 was acting up where it wouldn't change mode when the switch was turned. I pulled the fuse and cycled it and it hasn't come back.

Sometimes my wife complains that sometimes it switches out of 2WD but it's usually in wet conditions and she has made a tight u-turn or something. I'm assuming there is a traction control sensor that senses slipping and automatically switches it to AWD right?

 

[The_Roadie]

No traction control in 2002 Never had a mode switching feature either. Do you have the G80 code in your glove box sticker?

 

[MedicatedMike]

After several days and many 30-40 mile trips, it still hasn't shifted into AWD "by itself" like it was doing......so woooooot!!! :wootwoot::wootwoot::wootwoot:

I'm one of those OCD types as well and had to risk buying a used one with the "words" like I like and not those god awful new switches with arrows/symbols....lol...so I'm really surprised that didn't bit me in the rear.

*Got my used switch out of a 06 TB for $12 including shipping off ebay.

 

[EAnton781]

No traction control in 2002 Never had a mode switching feature either. Do you have the G80 code in your glove box sticker?

Yes, I have the G80 code. What does it mean?

 

[The_Roadie]

Yes, I have the G80 code. What does it mean?

If you're over 100K miles, have you changed the differential fluids? What's happening is that your wife is breaking one rear wheel loose probably punching it coming out of the turn, and the G80 automatic locker is engaging and that's a surprise if you're not expecting it or know what the traction improvement feels like. That's normal. If your wife claims she isn't punching it, then the G80 clutches are grabby and that can happen with stale, low or bad fluid. Also hugely important is to change the transfer case fluid every 50K miles. Are you current on that service interval?

 

[EAnton781]

Yes, flushed and refilled rear diff with amsoil and transfer case with the GM trek stuff 25k ago.

I'm sure she's not familiar with the feel of the diff locker as I've had to explain to her what is happening. However, why does the 4x4 light change from 2WD to AWD without turning the dial? Is this a normal result of the diff locker triggering?

 

[The_Roadie]

However, why does the 4x4 light change from 2WD to AWD without turning the dial?

The G80 is purely mechanical and gives no indication it's been activated except functionally. I don't remember you said the light on the switch changes. That's a bad switch.

 

[Up And Down]

Bumping this for some info. Does the 4WD switch need to be programmed when replaced? I know that some of the modules on these trucks do. Thanks in advance for the help.

 

[The_Roadie]

The switch is dumb. No programming needed. Only virgin TCCMs need programming.

 

[Up And Down]

The switch is dumb. No programming needed. Only virgin TCCMs need programming.

Thank you Roadie.