Service 4WD Light?

[AKDmax]

I have been seeing the service 4WD light come on just after starting the truck. Goes off after about 1/2 a second. Is this a normal self test thing with the computer(S)? No other problems other than the light coming on. Anyone know what this may be indicating if it's not a self test.

[pepperidge]

Mine did that last week at the Hunting camp and I was worried the truck might leave me stuck somewhere on a logging road in nowhere land Alabama. Could it be low fluid? I had mine drained/refilled with transynd not to long ago.
Or is it just a service reminder to change out the fluid. just hit 30k mi.

Anyone?

Thanks

[TxDoc]

This question was asked on another site and this is some info that was given:

I've heard there is upwards of 20 things that can set a service 4wd light, so its about impossible to know for sure what it is. But based on what I have seen on other forums, its more then likely the control head (push buttons) or the shift motor on the t-case.

Put that man on the payroll! (K-Kid!
When I had my '99 Z71, (with autotrac), on several occasions, the Service 4WD message came on briefly. The second time I took it in, no stored codes...wasted trip. But the switch did finally fail. It was out of warranty. I forget what it cost to replace, but too much. I think hastening its demise, was the fact I would dim my dashboard instrument lights. This caused the area immediately underneath the 4x4 switch to get very hot. New truck has the old fashioned lever on the floor. Autotrac was nice when it worked, but I prefer the back-to-basics lever.

maybe that will give you a place to start.

[TxDoc]

btw- if you go to gm-trucks.com and do a search under the 1500 area, you will get many hits. The recurring theme seemed to be the control panel switches. Good luck.

[CSDMAX]

AKDmax,

Same problem here. When I had my truck in for the leaking hydraulic booster, I mentioned it to the Service rep. and after servicing, he said there were no codes triggered and that it was probably the switch. I have not seen it appear for several weeks now, but if it continues, the stealer said they would replace the switch.

DON

[Lawnboy]

Wait a minute guys...!!!

I think AKDmax is simply seeing a "bulb" check at startup. At startup, ALL dash icons are illuminated on almost ALL vehicles. This is to ensure that the bulb isn't burnt out. He said it goes out in a 1/2 second.

IMHO, I don't think there is ANY problem here.

NOW, if it stays on, or comes on while driving or attempting to shift into or out of 4WD, then I'd suspect a problem.

I think you's be makin' a mountain out of a mole hill here.

[jmckelvy]

I had a similar problem with my truck. Service 4WD light came on, could not engage 4WD. The fault cleared after turning engine off and restarting. After doing this twice in about 2 weeks it happened again and would not clear. The dealer replaced the 4x4 switch and an electronic module under the dash. Worked fine again.

This as it turned out lasted about 1 month and the same thing happened. Dealer called Tech Support and they suggested check for loose ground wires. This turned out to be my problem.

The ground wire in question is on the engine side of the firewall, about the height of the brake booster and just to the left of the brake booster when facing the rear of the truck. It is a fairly large braided wire bolted to the firewall.

[SDWA]

Lawnboy - "Service 4WD" isn't a bulb illuminated light, it's a text message that appears in the message center, so it's definitely triggered by something. I've seen it pop up briefly on mine on startup twice (that I've noticed) in 6 months.

Scott

[ 08-29-2002: Message edited by: SDWA ]</p>

[AKDmax]

SDWA, you got it! Pops up in the message center and goes away. I shifted in and out of 4WD this morning and did't see the light. Doubt that fixed it though.
jmckelvy, thanks for the tip on the ground wire. I'll check it in the morning and post if I find something wrong.
I think this is going to be one of those "cannot duplicate" :mad: items at the dealer. It's going in for an alignment and leaf spring isolators soon anyway. Also spent a little time under it this evening looking for grease zerks and wiggling wires. Didn't find anything that looked out of the ordinary.

[dcpdave]

akdmax,
the svc 4wd light should not come on in the message center on start up. if it does, there IS a problem developing. g.m. has a service bulletin out to replace the engagement switch in the dash, the bulletin number is 02-04-21-004. because your light is only coming on for a brief second, it may, or may not store a code in the computer. if it is stored, it will be a "body" code b2725. we have replaced several of these switches. have your dealer test it. if it is the switch and he has one in stock great, if not, the last one i ordered(a few days ago) went on a back order, so it may be a bit for them to get one. if your truck is not under warranty anymore, it's a simple job to replace, you can do yourself.

hope this helps,

[Lawnboy]

Sorry Gang!

I just thought it was an idiot light.

Hell, I didn't even know there was such a thing as a "message center" . LOL

Just one more reason for me to start gettin' with the program and buy a new DMax!!

Hey, anyone want to "donate" one to me? Heck, I'd even take an ugly '03 if it were free!