4wd Service light

Sierra5.3 · April 10, 2003

Today I had my 4wd service light come on today when I was driving down the road. Has anyone had this happened to them?? Thanks

Kania2k1 · April 10, 2003

If you have the Auto-trac tranny, then it's the switches. I had that happen about a year ago. Just a quick switch out, bout 20 minutes.

THE BIGPUNN · April 10, 2003

kania is on the right track!

silverado man · April 10, 2003

Ditto you have to replace the switch it is about $40 at either of our supporting vendors. GMPartsDirect.com or Partszonline.com. That is what I had to do about 8 months ago. The part number for the switch is, 15709327. But if you still have warranty left just take it in and they will replace it for you.

seadoons · April 10, 2003

I think this happened to my brother's z also...the light came on (he has autotrac) but he could still switch it into 4WD (not all the time, but if you messed with it you could get it to work)...are these the symptoms?

silverado man · April 10, 2003

I think this happened to my brother's z also...the light came on (he has autotrac) but he could still switch it into 4WD (not all the time, but if you messed with it you could get it to work)...are these the symptoms?

Yeah those are pretty much the symptoms. Do the lights on the switch go dim that is also another symptom.

2porkchops · April 11, 2003

Just had my 'Service 4wd' light come on last night on my ride home from work. Dealer said it's safe to drive, will be bringing it in next tuesday. Will let you know how i make out.

2003 1500 z71 xc

Sierra5.3 · April 13, 2003

Is the switch difficult to install??

ClipperSkipper · April 13, 2003

It's not so much the switch, but the solder joints on the switch, and an easy fix according to the GM Techs in the 4x4 Chevy newsgroup.

silverado man · April 14, 2003

Is the switch difficult to install??

No the switch is not difficult to install at all, it might take you a good ten min. to do but that's about it.

Gilbert · April 17, 2003

GM has issued a service bulletin (dated Feb. 2003) regarding malfunction of the 4WD encoder motor on the transfercase of vehicles containing either the NP1 (NVG 263EAU) or NP8 (NVG246EAU) transfercases.

Models affected include 2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe; Also, 2003 GMC Sierra, Yukon, and Yukon XL.

The following is straight from the Service Bulletin:

CONDITION:

Some customers may comment that the service 4WD light has set and/or the 4WD is inoperative.

SERVICE DIAGNOSTICS:

Technicians may find a DTC (diagnostic trouble code) C0327 in the Transfer Case Control Module and/or DTC P0836 in the Transimssion Control Module and/or DTC P0500 in the Powertrain Control Module.

CAUSES:

Design issues within the encoder motor on the transfercase are leading to an incorrect voltage signal being returned to the TCCM, due to heat and vibration issues.

Engineering is aware of the issue.

--Replace the encoder moter with currently designed and released parts will most likely result in another customer concern in a similar time frame as the original concern.

--Timing for updated parts is unknown at this time.

--This bulletin will be revised when parts become available.

DEALER ACTION:

Record customer information on a permanent record so you may call the customer whenparts are available.

--For those customers who must have a functional 4WD, replace the encoder motor and advise the customer this is a temporary repair until the new parts become available.

--For those customers who are willing, remove the 4wd fuse. this will turn off the 4WD light and make the 4WD system inoperative.

Advise the customer that the availability of the new part is UNKNOWN at this time and that YOU (the dealer) will call them as soon as the parts become available.

Whoooo!

FYI:

I have read from some owners on other forums that have had their 4WD kicked in to low all by its self. So watch out. Your dealer is playing with your life by telling you it's OK to keep driving it around. Another owner mentioned that his tranny kept going into neutral. So far, mine has worked flawlessly, but then again, my truck only has 1000miles.

From literature that I've read, it's my understanding that GM, in an effort to reduce production cost, changed parts suppliers from the earlier tranny modules used in the 2002 models. Hence, this TSB (tech. service bulletin) only affects 2003 model GM's with 4WD and the transfer cases mentioned above. I have already mentioned this to my Dealer and had them put my name on a waiting list for the corrected part(s) when released. I suggest you do the same.