HELP!!! Tow Vehicle Problems... need knowledge

#1

I’ve got a 2004 Chevy Suburban Z71. I had my “Service 4WD” light come on a couple of weeks ago. The car was sat for a week of that time.

I took the car to the dealer to have them read the codes. They called back and said the 4WD Module was bad and it needed to be replaced. And for $706 (parts and labor) they could have it ready for me in the morning…

So I said “I’ll be right up to get it”

I tried searching to figure out what I need to know before shelling out new RA1’s sums of cash… problem is, all I could find we’re forums that charge to answer questions or it was real wishy washy with details. Something about… “pulling the fuse for 30 seconds then it should reset and if that doesn’t work, you’ll have to get the dealership to replace it, cuz they have to program it”…

Thing is the cars driving fine. We were planning on taking the dogs down to ATL for thanksgiving.

What say ye? If any of you can shed some light on this subject, I’d be very appreciative. (that means free beer)

#2

Probably as long as you don’t need to engage 4WD you will be fine. I will bet you cant engage it.

My tuck (Nissan Titan) get the 4WD light to come on sometimes. Its usually a bad ABS sensor. $145 for sensor and $100 to install. When that light comes on I can not engage 4WD since its all computer controlled for the front limited slip.

You need their “Xcon 5000” tool to tell you what sensor is bad or you can pull all four and test them individually for resistance. Real pain.

Modern cars and trucks are just a pain and when a computer or other electronic goes bad it usually shuts down whatever subsystem in bad. I got hit in a snow storm and lost my 4WD. Made for an interesting drive.

If you can find a good independent service center the fix may cost less.

#3

My “service 4wd” light has come on a few times (03 Avalanche Z71, same rig) and has always gone off on it’s own. I think it’s triggered when you try to switch into 4wd and there’s an error somewhere. Have you flushed the transfer case fluid? If not, you might be due, and that could help.

#4

Scott

I would bet you’ve got a bad switch or sensor on the transfer case or bad switch on the dash. Did you try searching some of the Chevy/GMC truck forums? I assume this is one of those Auto 4WD systems that you just turn a switch on the dash?

If this is a long term vehicle, I would invest in the factory service manual and a cheap generic OBD II code reader - assuming the 4WD codes are not GM specific and you need a GM Tech II scanner to read them.

For now - see if the thing will go into 4WD - and if there really is a problem, crawl under there and make sure all the sensors are plugged into the tranny and t-case. Next step would be to unplug and spray them with brake cleaner. Make sure none of your wires have melted against the exhaust.

If you can actually isolate it to this “4WD module” then I would start searching local wrecking yards or GMPARTSDIRECT.COM - they are usually 30% cheaper than the dealer…