2003 Silverado Z71 Service 4wd

cjskelton · August 7, 2010

I am new to this so please bare with me. I have been reading all about what the problem could be when the service 4wd light comes on but getting a definitive answer has become difficult. Here is my problem, The service 4WD light is on constantly and does not shut off. The truck is in 2WD, all of the lights on the 4WD control switch are off with the exception of the back lights. I can not switch to 4WD at all. I have had a friend of mine connect his Snap-On analyzer to pull the codes and when the vehicle is off he gets the message referring to the transfer case and then when the truck is turned on he gets no reading. I personnaly have pulled the 4WD control switch out of the dash to check for loose solder connections and there are none that I can see. There is a circuit board inside of the switch that can not be removed without damaging it. All of the fuses in the engine compartment have been checked as well as the ones on the side of the dash inside the truck and they are good. I am at a loss at what it could be because there are so many things that it might be, encoder motor, transfer case control module, loose wiring, etc.... I have made an appointment with a dealership to try and pull the codes at a charge of $92. If anyone has any suggestions I would be greatly in your debt. Thanks

Majorleaguebass · August 7, 2010

replace ur 4x4 switch...common problem

gmtech4 · August 7, 2010

no one charges that much to scan a veh,but ,your switch may be bad and has a code for it ,2725 or something close to that ,they are a POS switch alright

Z45 · August 8, 2010

Delphi made parts that had high failures and likely led the the demise of Delphi. GM had to sue them to get satisfaction for all the bad electronic parts they supplied to GM.

Monday, September 10, 2007

Delphi settles GM parts issue

Company pays $100M to mend warranty issues and agrees to replace 1.1M electronic parts.

David Shepardson / Detroit News Washington Bureau

WASHINGTON -- Delphi Corp. will pay General Motors Corp. at least $100 million to settle long-standing disputes over warranty issues and also will replace 1.1 million electronics parts -- worth more than $80 million -- at no charge as part of a wide-ranging agreement between the companies.

The settlement, reached Aug. 14 and made public late Thursday, opens a window into the costs GM has incurred in dozens of recall campaigns as a result of parts supplied by its former parts unit. GM has blamed dozens of warranty claims on shoddy Delphi parts, especially electronics.

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Meanwhile, two GM investigations into other allegedly defective parts by Delphi remain ongoing, "and GM has not yet determined if Delphi has any responsibility," according to the agreement

My06GMCSierraZ71 · January 4, 2011

I am new to this so please bare with me. I have been reading all about what the problem could be when the service 4wd light comes on but getting a definitive answer has become difficult. Here is my problem, The service 4WD light is on constantly and does not shut off. The truck is in 2WD, all of the lights on the 4WD control switch are off with the exception of the back lights. I can not switch to 4WD at all. I have had a friend of mine connect his Snap-On analyzer to pull the codes and when the vehicle is off he gets the message referring to the transfer case and then when the truck is turned on he gets no reading. I personnaly have pulled the 4WD control switch out of the dash to check for loose solder connections and there are none that I can see. There is a circuit board inside of the switch that can not be removed without damaging it. All of the fuses in the engine compartment have been checked as well as the ones on the side of the dash inside the truck and they are good. I am at a loss at what it could be because there are so many things that it might be, encoder motor, transfer case control module, loose wiring, etc.... I have made an appointment with a dealership to try and pull the codes at a charge of $92. If anyone has any suggestions I would be greatly in your debt. Thanks

This might help you, I have posted this on several different threads for the same reason. I have a 2006 Sierra Z71 and have had problems with the 4WD for some time now. My truck would go into 4WD on its own and then wouldn't go into 4WD when I wanted it to. The light would say one thing, my front end grinding around corners and poor fuel mileage said another. I took it to the dealership, they charged me $100 to tell me what was wrong. It was the Encoder Motor on the transfer case and the Transfer Case Control Module. They wanted $1600 to fix it. BUT... I have some good news for people with the same problem!! The Transfer Case Control Module is located under the driver side dash, just above the E brake. You DO NOT need to take apart the dash, at least on the 06 model. I changed the TCCM in about 10 minutes in a freezing cold parking lot. The Encoder Motor I bought a new rebuilt off Ebay from BuyAutoParts.com for $250 and that included shipping. The company was great to work with as well. It was VERY easy to change with basic hand tools. I had it swapped out in 30 minutes, start to finish and was driving it 5 minutes later. I know my way around trucks a little, but I am far from a "mechanic". My 4WD works like a champ now. Take it from me, don't pay thousands for labor because it wasn't hard at all. I hope this helps someone out there and Good Luck