hi
i have an '04 silverado hd2500 4x4 with an 8.1 and allison trans w/electronic 4x4. the problem i have-and it's happened 5 times so far (under 6k miles) is none of the 4x4 lights come on when i start it and the odimeter error msg comes up to service 4x4. has always happened the 1st start up in the morning when it's been cold out(was winter so was always cold) this happens usually on the way to work and by the time i go home it's working fine. dealer has been told about it but unless it happens when i can get it to him to see/check out he says not much he can do at the moment. luckily so far it has always been stuck in 2 wheel drv. anyone else have this problem or have any ideas on the cause/fix for it?
thanks
2004 silverado 2500HD crew cab 4x4 long bed 8.1L gas hog
2006 skyline nomad 3260 platium edition, prodigy, reese dual cam
1 very part time camping son and 3 full time camping, 4 legged fur balls
1 SU (spousal unit) who loves rv'in as much or more than me
I have had the same problem with my 01. It would never save a code so my dealer would not believe me. His answer was to bring it in when it happened. As it only happened at start up and not consitently, I could never get it to happen for the dealer.
As I understand the problem is the computer can't always communicate right away at start up with the 4x4. so the light comes on. After it can communicate with the 4x4 the light goes out. water in the plugs or poor ground seems to be the possible problems. what I did is pull every plug on the transmission and 4x4 and put a dab of dilectric greese on each contact and re insert the plug. Since then I have only had the problem a few times usually in very wet weather.
Hope this helps
Gordon
2001 GMC Sierra 2500HD L/B E/C D/A 4x4
2003 Eagle Cap 950 Loaded
Overly complex because they've dumbed it down for the newbies who really don't know the HOW2s nor willing to learn, so dumbed it down by making it computer controlled. So complex, it's tough to DIY and costly too.
Typically it's either the dash button assembly (one, as a lot of newbies try to engage both buttons at the same time, so there is an interlock in there). About $58 bucks plus 1-2 hours labor.
If it's with the motorized shifter on the case, that is about $500 bucks just for the assembly and then about 4 hours labor.
If it's in the computer, most of the cost will be in the diagnostic labor and usually open ended. Or they will just toss the computer and replace it. Don't know the cost of the computer, yet.
Open ended as it could be just the adjustments of the motorized shift assembly. Various limit switchs, but that takes a lot of time and need a computerized scan tool to do it from what I've read over at the Suburban board.
Since you have the 04, not the front diff actuator. OBS has a heater to vaporize liquid. That vaporized liquid increases pressure in that chamber, which pushes a diaphram to engage the front diff. Changed to motorized (solenoid) actuator for the NBS.
Suggest you have a 4x4 shop take a look. Too many dealers don't have 4x4 folks on their staff, so know nothing more than what the manual says, which is usually to replace it after a bit of diagnostics.
Simplist is that a fuse has gone, but find out why it blew before just replacing it. You'll have to replace it to find out, but don't leave it assuming okay. There maybe an underlying problem that will cost much more down the road.
Overly complex due to dumbing it down for the newbies. So complex it's just stupid and expensive for the sake of dash mounted buttons. I'll take floor mounted, manual levers anyday.
Why I tell anyone asking if they should or not..."if you have to ask, don't get it...you'll know when you need it". It's been bad for the 4x4 breed.
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...
There was a bulletin out when I had the same problem with my '03 3500 4x4. It's been so long that I've forgotten exactly what it was. They had to replace some switch or something in the front end. The truck was going into 4wheel without me doing anything. It was warranty work.
USE UP FOREIGN OIL BEFORE WE USE OURS. (leave it under our soil until they're out of it)
The World is a book and those that do not travel read only one page.
I work at a gm dealer as a tech. I am very sure that you truck will have a code C0550 and the atc module needs to be reprogramed. I am not sure how your dealer can be unaware of this it is covered by a tsb. Reprograming the module will take about 45 minutes.
My 01 6.0 2500 Suburban would sporadically display the Service 4x4 light. Internet research revealed this is commonly the dash switch, which is more than just a switch. The switch lights would also go on and off at will. I watched this for several thousand miles. The switch was just $49 (less than the cost of one dealer diagnosis, assuming they could anyway!) online so I bought one, installed it, and the problem is fixed. This fix may only apply to '01s.
GMCDually wrote: I work at a gm dealer as a tech. I am very sure that you truck will have a code C0550 and the atc module needs to be reprogramed. I am not sure how your dealer can be unaware of this it is covered by a tsb. Reprograming the module will take about 45 minutes.
I agree with this also. I had the service 4 wheel drive light come on in my 2003 2500HD and before I got it to the dealer it was working fine. The dealer told me they still need to reflash the computer even though the light was no nonger on. From what I hear it is actually fairly common.
Bryan
2003 2500HD Ext. cab short box
6.0 liter 4.10 gears, Nelson performance PCM
98 K1500 4x4 heavy duty 1/2 ton
6,600lb GVWR 5,280lbs on the scale empty
14 bolt rear diff. 3:73 , Tranny and oil coolers
280,000 miles still purrin' like a kitten
This happened to my 04 Silverado when it was almost new, turned out to be a faulty ground in the vehicle. Apparantly they fastened on the ground wires after they had undercoated the truck, poor contact.
Frank and Deb
2004 2500hd d/a prodigy
2004 Cedarcreek 37rdqs
duluth, mn
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