The 4WD transfer case encoder motor position sensor or the selector switch may fail causing the service 4WD message to be displayed. Fault code(s) stored in the transfer case control module will be of assistance in determining the exact fault causing the message to be displayed.Google+
Car Problem Reports
Chevrolet Silverado 1500 4WD Transfer Case Position Sensor/Selector Switch May Fail
Chevrolet Silverado 1500 Problem
Drive Trains Affected: 4WD, Automatic Transmission
Average Mileage: 120,459 mi (2,000 mi - 277,000 mi)
I have found out that usually the two ground wires that are attached to the frame right under the front of the driver’s door is the culprit that causes the 4wd selector switch in the dash to go bad. Chevy had the bright idea of applying the undercoating and/or not cleaning the point of contact of the ground wires before they bolted them to the frame therefore overtime moisture, dirt and corrosion affects the contacts of the threads of the bolts which are the only source of ground the two sets of wires have. There are 2 things you will need to do. First you will need to take the bolts out and use a wire brush to clean down to the metal of the frame as well as the bold threads and ends of the wire attachments and then reattach the ground wires to the frame (time to complete – less than 5 minutes). Second you will need to replace the 4wd selector switch in the dash. You can purchase this online from Amazon (Dorman 901-062 4-wheel drive switch for $31.15 – no tax or shipping and handling). To replace, gently pull the outer trim of the dash out by using just your fingers. You do not need to completely remove it, just pull it out far enough so that you can pull the old switch out of it slot. Then unplug the two plugins located in the back of the switch. Plug them into the new switch and push the switch back into the slot and then push the trim back into place (time to complete – less than 5 minutes). This should take care of your problem. Most often, people make the mistake of just switching out the dash switch and when that does not correct the problem they then replace the more expensive and time consuming actuator motor and location indicator on the transfer case that does not need to be replaced. I should point out that when the Service 4WD light comes on, there are no codes that show up on the code readers which is awful strange in its self. I hope this helps everyone with this problem because I sure wish I knew this before my many costly and time consuming trips to multiple repair shops including the dealer and none of them were able to successfully repair the problem. It sure seems like Chevy could release a repair bulletin so that everyone could fix Chevy’s blunder. I bought my 2005 Silverado new in September of 2005 and this has been the only major problem I have every had with this truck with the exception of the check engine light that came on this past spring and the error code was P0446, which was the Vapor Canister Purge Valve. They have since come out with a new conversion kit that cost close to $100.00 and is very time consuming to replace. I highly recommend that you can purchase the original equipment part from Amazon – ACDelco 214-2147 OE Service Vapor Canister Purge Valve for $16.36. You will have to cut the vent tubing right at the old canister and use a 2 inch long piece of vacuum tubing the next size up to attach the new canister because the original tubing is hard and cannot be stretched to remove on to reinstall the new part. The canister is located at the back of the gas tank and can be accessed without having to even jack up the truck. It clips right onto the back of the gas tank and has one plug in going into it (time to complete – less than 5 minutes). Best wishes, Mike Gilbert, St. Joseph, MO
no lights at the selector switch, service four wheel drive message, changed selector switch,encoder,fuses check wiring harnesses replaced front actuator still no luck, the selector switches lights do flash when the key is turned to start the truck
Visitor, 2005 Chevrolet Silverado 1500, 4WD, 150,000 mi
automaticaly shifts itself in to four hi or four low when i start it and says sevice 4wd
Visitor, 1999 Chevrolet Silverado 1500, 4WD, 114,000 mi
electronic pushbutton panel for 4WD intermittently stops working and cannot get vehicle into 2WD or 4WD; lights go completely out
Visitor, 2005 Chevrolet Silverado 1500, 4WD, 47,000 mi
the four wheel drive indicator switch switches almost everytime I start the truck. when I try to switch it using the buttons nothing happens. It seems like the truck has a mind of its own at times and will change in to four wheel drive low and it makes it hard to accelerate.
Visitor, 2000 Chevrolet Silverado 1500, 51,000 mi
service 4 wheel drive light comes on when driving for a short time
Visitor, 2004 Chevrolet Silverado 1500, 4WD, 200,000 mi
While idleing truck will put itself into 4 low, I put truck into neutral and gassed it then tried to push buttons to put back to 2 wheel. Put it into gear and gassed hard and could hear it click back. Keep wanting to put itself into 4 low though
Visitor, 2003 Chevrolet Silverado 1500, Automatic Transmission, 64,000 mi
push button engagemaent of 4x4 and 4x2 somrtimes will not engae at all. Usually transmission will default to computer controlled four wheel drive. After vehicle sits for a few hours push button control returns.
Visitor, 2000 Chevrolet Silverado 1500, 4WD, 142,000 mi
I bought a new switch online for $35 and replaced it myself. Quick and easy.
Visitor, 2006 Chevrolet Silverado 1500, 4WD
I bought a 2006 Silverado that has a service 4 wheel drive light that comes on when driving for a short time. I notice that a visitor posted that he bought the switch to resolve the problem for 35.00 online and replaced it himself. If I can the info. from the place the switch was purchased will be helpful. Thank you.