another service 4wd light question

slimjim2525 · January 11, 2005

When I came out of work today and started the truck I got a service 4wd light in the DIC. Stopped at a store on the way home, again I got a service 4wd light on start up. Proceeded to call the dealer and bring it to them, and when I started it now the service 4wd light is out, and the light by the 2wd drive button is now on, where it had not been, and it will now engage 4wd. My question is, will this problem throw a code that the dealer can identify? It sounds like a switch problem from what I'm reading. And should they replace the switch anyway? Thanks in advance

silverado man · January 11, 2005

I'm almost sure that it is the switch. To be sure you can take it to Auto Zone and have the codes read for free. If you decide that you want to replace it I would replace it yourself and not take it to the dealer it is a 5min change and you can save $100 or so.

slimjim2525 · January 11, 2005

yeah i hear ya, but the truck is an 04 silvy ex cab with only 14k on it, so i figured it's still under warranty.

silverado man · January 11, 2005

Than take it to the dealer. And let them worry about it. Most likely they will just replace the switch.

Yukon04 · January 11, 2005

Same situation happened to me last week. The 4X4 switch lights went out in the morning and the 4X4 was disabled. In the afternoon, everything was fine and worked OK. Anytime a "check engine" or "service" light comes on in the dash, a diagnostic trouble code (DTC) is set. Whether the light is still on or turns off, the DTC will be stored as current or history, respectively. The dealer should be able to read the DTC that was stored. In my case, the transfer case module went bad. I had 12 DTC's stored as history in the module. Replaced under warranty. No issues since.

slimjim2525 · January 11, 2005

well here's the update. Just got back from the dealer, and was told that there was no code stored, and that they reprogrammed the transfer case module. Does this make sense?

Yukon04 · January 11, 2005

Sounds like BS to me. Whenever a light comes on and a "function" is disabled, in our case 4x4, a DTC is set. Not sure what they did, but I know that they had to reprogram the t-case module after replacing mine with a new one. Dealer maybe legit, but next time try and pull codes another way. Scantool, power programmer, etc...but make sure during this process that the history codes are not erased. Then bring it to your dealer. Good luck.