Silverado Service 4WD

[Don E. Foster]

Maybe it was on this site that I once saw posts concerning the message concerning the Silverado PU "Service 4WD". I am now getting that and all seems OK to me. Any comments?

Thanks

 

[Steve in IN]

A thread started up about this the other day on another site I frequent. Maybe you frequent there too:

http://www.weekendfreedommachines.com/cgi-bin/discus/board-auth.cgi?lm=1206398643&file=/46918/309372.html
service 4wd on WFM

 

[john_Bud]

I couldn't follow the link - not a member

There are a couple things that will give that message. In order of cost, low to high...


First is low electrical reference voltage. The ground for the system is on a cross bar under the truck about at the location of the drivers left foot. Yes, that's right in the road salt splash zone! There are 2-3 ground wires connecting there. Take off the bolt, sand down to clean bright metal on the frame and wire ends and bolt/nut. Put it all back together tight! Then with a can of spray under coat give it 3-5 light coats over the span of an hour or so and a couple heavy coats getting around the back sides and all that.

There is also a ground in the dash that the 4wd system / switch uses. Clean that one good too. But you don't need to undercoat it!

The switch may also be bad.

Last there is an encoder wheel assembly telling the hubs to lock and if that happened that goes bad.


If you are lucky, it's the ground or the switch. My guess is that you will be lucky as the encoder failure usually results in the 4wd indicator lights all blinking as the computer doesn't have a clue what is going on. The "Service" is probably the ground.

Here's to good luck!

jb

 

[T.C. in Tx]

The service 4 wheel drive light kept coming on on my 2001 Chev HD. Had it checked a couple of times and nothing seemed to be wrong with the transfer case.

There is a discussion thread on the Diesel Page to the effect it was likely the switch. So I ordered a new switch from GM Parts Direct and it seems to have fixed the problem. Easy to replace by just popping off the dash cover and unplug/plug.

Part number 15063844. Cost was $39.93 plus $4.04 handling and $6.91 shipping. The price at the local Chev dealer was over $68. Good luck.