Service 4WD Message

2500HD4X · September 6, 2004

Hey all- I know the service 4WD thing has been hashed to death on here, but I just got it myself. Therefore I need reassurance. I just installed a new dual tune PCM last week. I got the service 4wd message after driving it about 100miles and then it just went out. All the 4WD buttons were working, it went in and out of 4WD fine. Well this morning, while getting pummelled by Tropical Storm Frances- The stinking light came on again.....It went into 4WD fine, but seemed a little balky going back in to 2WD (Had to hit the button a few times it seemed like). Restart, the light was out.

My question is this, is the service 4WD message related to installing a new PCM, or is it just perfect timing for the buttons to go out? Somebody please help, I don't know whether to blame the PCM for the trouble, or just replace the buttons..... It is making me !

toddoughty · September 6, 2004

Hey all- I know the service 4WD thing has been hashed to death on here, but I just got it myself. Therefore I need reassurance. I just installed a new dual tune PCM last week. I got the service 4wd message after driving it about 100miles and then it just went out. All the 4WD buttons were working, it went in and out of 4WD fine. Well this morning, while getting pummelled by Tropical Storm Frances- The stinking light came on again.....It went into 4WD fine, but seemed a little balky going back in to 2WD (Had to hit the button a few times it seemed like). Restart, the light was out.
My question is this, is the service 4WD message related to installing a new PCM, or is it just perfect timing for the buttons to go out? Somebody please help, I don't know whether to blame the PCM for the trouble, or just replace the buttons..... It is making me !

<{POST_SNAPBACK}>

Mine kept doing that too. Kept bringing it in and found nothing.

Eventually, they replaced the buttonsl ( or the switch assembly it was tied to) and it fixed the problem. Turned out being electrical, but not PCM or drive train.

2500HD4X · September 7, 2004

Well, it came on again- happened to be driving past Auto Zone this afternoon through the wind and rain and had the guy plug it up to a code scanner. No codes stored. Guess I will try replacing the switch tomorrow since it doesn't seem to be PCM related. Oh well-Hope that fixes it. I hate the big yellow dash light... I even hate it when it tells me I am low on washer fluid.....MUST KEEP YELLOW LIGHT OFF!! IT MAKES ME !

GMCTech · September 7, 2004

There is a software update that GM has released to address Service 4WD light on with no codes present.

My guess is you'll need to get it updated.

Hope this helps.

2500HD4X · September 7, 2004

Isn't this just on the 03's and up? Thanks for the input, if the replacing the buttons doesn't get it, I will try that. It comes on after driving about 8-10miles.... feels like it is in auto 4wd, but the light shows 2hi....Just got off the phone with the dealer, they have 2 in stock. On my way to try it out.

jcebruin · September 8, 2004

Well this morning, while getting pummelled by Tropical Storm Frances- The stinking light came on again.....

I had the switch replaced on my 04 yukon. We got a rain storm that lasted about a week, and by the end, my swith went out with the service 4wd message. Anyway, as soon as the rain stopped and the truck dried out, the problem "fixed" itself. I took it in, and the dealer replaced it without any hassle.

Haven't had any problems since it was replaced, but it hasn't rained as much since then either....

hope this helps.

J

2500HD4X · September 8, 2004

Well, I replaced the switch and drove it around a good bit, I have gone successfully for about 25 miles without the dreaded yellow light... It seems to have been the switch. They ran it on the Tech 2 and the guy said, yep its the switch. 5 minute install-$55.00. Hopefully no more yellow light of DOOM!!!

Blue-2001-Z71 · September 8, 2004

Well, I replaced the switch and drove it around a good bit, I have gone successfully for about 25 miles without the dreaded yellow light... It seems to have been the switch. They ran it on the Tech 2 and the guy said, yep its the switch. 5 minute install-$55.00. Hopefully no more yellow light of DOOM!!!

<{POST_SNAPBACK}>

Yeah, the 99-02 trucks seemed to have problems with the switch and sometimes the shift module in the case. the 03's and up usually need a reflash. I got lucky, found the switch for mine online for $38 and have NEVER had that stupid light come back after almost 10K miles. Hope you have the same luck!

boutbroke · September 26, 2004

Please post your finding. Just got the fuel sensor / low fuel light fixed on my '99 Z71 and now I get a Service 4WD light in it's place. I took it to my mechanic who ran some test and said everything was working fine, no codes, lights on, 4WD engages, etc. It clears when the ignition is turned off and on but still comes back eventually.

He felt the problem might be in the wiring to the transfer case lock solemnoid.

Blue-2001-Z71 · September 26, 2004

That's exactly what mine did. I would be driving and the Svc 4WD lt would come on but would clear by cycling the ignition switch. GM Parts Direct has the switch for $31.89 and the light hasn't come back since May when I replaced it. No guarantee but that's what's worked for most of the 99-02 Autotracs here.

GM PART # 15709327

CATEGORY: All

PACK QTY: 1 CORE CHARGE: $0.00

GM LIST: $55.95

OUR PRICE: $31.89

DESCRIPTION: SWITCH

2500HD4X · September 27, 2004

Well, It has been several weeks and I have had no more SERVICE 4WD lights. Apparently the switch was the problem......I know it is available online cheaper but I was and still am into instant gratification. $38+shipping and a 2-3 day wait VS. $55 and now, it was an easy decision..... Good luck w/yours boutbroke, I feel your pain! The guy at the stealership told me they see a bunch of these every month and that is why they keep 2 of the switches on hand. It is a really easy install, just drop the steering wheel all the way down, pop off the dash and unplug the switch assembly. It literally took about 3 minutes in the dealers shop to swap it out. Still no light and about 600 miles on it now.