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4x4 engages without driver input !!

boomer 33

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boomer 33 Enthusiast

boomer 33

Posted
Posted

When I fire it up and head out, it could select auto 4x4 on it's own, or even go down to 4 wheel low !! Sometimes it shows "neutral" . Have to pull over, put it into neutral and rock it a little to get it to disengage. Took to dealer and he replaced the dash switch, but it still has a mind of it's own. I have a Westers tune and don't want it to be overwritten, but after doing a search here, it looks as if that has helped some folks when the dealer did a computer flash.

Anyone else have some experience with this situation?

 

2004 Yukon XL 2500, 8.1 with 4.10 gears. 51,000 miles

 

Thanks, Boomer

boomer 33 Enthusiast

boomer 33

Posted
  • Author
Posted
When I fire it up and head out, it could select auto 4x4 on it's own, or even go down to 4 wheel low !! Sometimes it shows "neutral" . Have to pull over, put it into neutral and rock it a little to get it to disengage. Took to dealer and he replaced the dash switch, but it still has a mind of it's own. I have a Westers tune and don't want it to be overwritten, but after doing a search here, it looks as if that has helped some folks when the dealer did a computer flash.

Anyone else have some experience with this situation?

 

2004 Yukon XL 2500, 8.1 with 4.10 gears. 51,000 miles

 

Thanks, Boomer

 

 

 

 

 

 

TTT

boomer 33 Enthusiast

boomer 33

Posted
  • Author
Posted

Oh Well, guess I should have made my question into another stupid poll, Should have read " How Many have had 4x4 problems" or "What color is your truck when the 4x4 does not work"

Shhesh.

Burbman Enthusiast

Burbman

Posted
Posted

No, no experience with this issue, and haven't heard of anybody else with the problem. The transfer case is all computer controlled, so you need some serious diagnostics here....could be an intermittent short in a wiring harness, could be a PCM issue, or could be a problem with the Wester's tune. Maybe youy should have the PCM reflashed by Wester's first so you don't lose the tune? Could also be the switch and the dealer replaced witha defective one...unlikely but it's happened.

 

I would think if it's acting this wierd, there should be some codes stored in the PCM that the dealer could extract and use to diagnose.

  • 2 months later...
DaveK Enthusiast

DaveK

Posted
Posted

Boomer,

I have exactly the same issue with my 2003 Sierra 1500HD. It's been going on for months now exactly as you described it...very intermittantly. Mine will start up in Auto 4WD, 2WD, or Neutral (I've never had it start in 4Lo). Everytime I switch it back to 2WD I get a "Service 4WD" on my information center. I've had it to the dealer twice now...naturally both times it was working ok and they said there was no code logged into the computer.

I suspect it's not the switch mechanism but maybe a sensor somewhere in the system or maybe the computer. Anyway it happens in cold, cool, hot, and warm temps so it doesn't seem temp related.

Hoping someone can identify this problem...want it solved before hunting season when I really need it.

Jimmy J Enthusiast

Jimmy J

Posted
Posted
Mine went away. but now is happening evertime I start up for the last 2-3 days.

 

 

 

 

 

Doesn't WESTERS offer some sort of re-tune/re-flash for return customers. I'd call 'em, tell them what is happening, and see what they can do for you IF... you were to take your rig into your local dealer and the dealer reflashes the pcm. Just my 2 cents.

  • 3 weeks later...
BrentNewland Enthusiast

BrentNewland

Posted
Posted

If your truck has the round Auto 4WD button, it will automatically engage the 4WD, whether or not the button is pushed. I work at an emission testing center in colorado, and all new GMC/Chevy's with this button have to be given an Idle test instead of an IM/240 test.

dizzy Enthusiast

dizzy

Posted
Posted

My 2000 Silverado Z71 did the exact same thing, Service 4WD would light on the dash, it would randomly display the wrong gear or it would not light the LED's at all.

 

As mentioned above, mine also had the "Auto 4WD" option. I replaced the switch myself (about $65 bucks from dealer) and it fixed it, took me all of 5 minutes to replace. Low range actually worked after that.

 

Mine didn't seem to be actually switching gears it would NOT go into Low range. If you didn't get back the "old" switch from the dealer or physically see that it was replaced, I would go buy another switch and replace it yourself.

azswede1960 Enthusiast

azswede1960

Posted
Posted

I have a 03 Z71, and I also have the same problem, where the autotrac can start in ANY position, OR be totally OFF .....

 

I have a friend with same year truck, so I tested with his switch and ECM with no luck .... I think I have Encoder Motor Sensor problem .... Ordered one at GMPARTSDIRECT and I am on my knees praying as we speak, that it will work!!!!

 

One thing is FOR SURE: My next truck will have 4wd shifter on the floor :cheers:

  • 11 months later...
HDSpence New Member

HDSpence

Posted
Posted

My 04 hd2500 also does this. I start the truck (after having shut it off in 2w hi) and the 4lo button will be illuminated, but the transfer case is in 4hi. Sometimes I have to drive about 50 miles, turn ignition off for awhile, then jump back in and hit the 2hi button for it to shift back to hi gear. After that, the engine light comes on and service 4wd comes up. What is the prob? One dealer told me it was an actuator in front diff -quoted $1000 to repair. I think he was trying to break it off in me....Trying to figure it out myself. Any help would be appreciated.

Haulin' 8.1 Enthusiast

Haulin' 8.1

Posted
Posted

The transcase motor/encoder is availiable as a reman from auto parts stores. I don't remember the exact price but it seems it was around $200. They have a core charge. Three bolts hold it on but you'll probably have to disconnect the front driveshaft from it's diff to gain access. The motor is relatively easy to replace. Don't test it off the case. The trans case selector shaft can be manually adjusted with a 15mm wrench.

 

Vernon

99 2500 Enthusiast

99 2500

Posted
Posted

Had this same problem on my brother's 2000 silverado, after a lot of hair pulling I found that one of the wires going to the encoder was open. Traced the problem to the electrical center under the hood, a rat decided to eat right through the wire and eat the insulation off of some other wires.

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