Service 4WD Light

oldredhat6 · February 19, 2005

Have been experiencing my Service 4WD light coming on. Also last week when I tried to engage the 4wd it would not engage into 4hi or lo. Then once I turned off the truck and restarted it, it would go in. Then I had to do the same to disengage it. I have the push button 4wd on the dash. Do not like it, but they did not have the floor shift when I bought the truck.

Has anyone else experienced this? Is there a way to check the codes? Any help would be appreciated before I break down and take it to the dealer.

99silveradoz71 · February 20, 2005

The switch has been a fairly common problem on the nbs trucks. My light went on and that ended up being the solution.

oldredhat6 · February 20, 2005

The switch has been a fairly common problem on the nbs trucks. My light went on and that ended up being the solution.

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Is there a way for me to check this through an engine diagnosis or such? Appreciate the feedback.

airbalancer · February 20, 2005

I think trucks are run with a XP OS, because something you have to turn it and off and restart to get it working

71GMC_3/4T · February 20, 2005

I had this same problem Wednesday night on the way home in my '03 K2500HD Crew. I pulled over, shut it off and restarted it and it still didn't work. When I got home, I shut it off again and restarted it and still no worky. About the only thing different that day was that I parked my pickup facing north and the sun may have warmed the switch module in the evening. Usually, I park facing south in the winter.

I went in the house, launched Google, and did a search for "Service 4WD" and found that most of the problems were due to the switch. I went back outside, pushed all the buttons several times with it off and it came up normal and hasn't failed since. When it wasn't working, I couldn't change modes, stuck in 2WD, and none of the LEDs were lit. I can't remember if the backlights were working or not.

I hear it's a cold or cracked solder joint in the switch module, so I plan to fix that myself instead of letting the dealer fix it under warranty. That way I know it's fixed, instead of getting the "could not duplicate problem" answer from the dealer. I plan to pull the dash panel overlay when it's warmer so I don't crack the plastic parts.

Take it to the dealer and tell them to change the switch. Keep an eye on it as it may fail again if they put the same replacement switch back in. That's why I plan to fix my own. I know how to solder quite well...

Good Luck ol' RedHat6, And let us know if the dealer changes it out even if it's still working when you bring it in.

dbajaer · February 20, 2005

I have had the exact same problem with my 2003 2500HD Diesel. I also have the service brake light problem also, they are I think unrelated. I am scheduled to have the 4 wheel push button switch replaced. They have never found the reason for the brake light and warning bells that go with its failure. My tranny was pulled for a leaking pump and the four wheel started after that repair, lots of attempts to repair but never can fjind the problem, even when showing up with the 4 wheel fault light on. Hope my switch change gets the 4 wheel part fixed. It does make it hard for one to even think about selling truck as what can we tell the buyer? Are we trapped into only a trade in? On one dealer visit they found the cigarette lighter fuse blown and I guess this can cause some of the problems, it was better after that but still occurs at times.

8100 Power · February 20, 2005

Ive got a solution!

Replace the switch, thats what i done, and no light since......!

71GMC_3/4T · February 20, 2005

Well, I pulled the switch this morning. Getting it out wasn't much trouble at all. Had it removed and in my hand within 10 minutes.

It took me a while to get the switch apart, but with patience it can be done without breaking anything. I checked all the solder joints under a magnifying glass and didn't see any cracks in the solder around any of the pins for the connectors. I desoldered and resoldered all the pin connections anyway. We'll see... I'm now wondering if it might be a bad ground where the black wire off the harness eventually ends up. It's probably grounded to the frame somewhere with a lot of other black wires. That could also explain why none of the LEDs would light up.

I remember having trouble with ground wires up under the dash on my '83 S-10, where all the indicators on the dash would light up when the headlights were on. Maybe it's time to go on the hunt for bad grounds. I thought that was a mopar problem though...