Service 4x4 light on dash. 2003 GMC Sierra 1500hd 6.0 4L80E, fully automatic 4x4. Has been working on and off. Usually the light is off after a few days, then the 4L lights up and stays on even though I am driving freeway speeds, transfer case is in 4H but dash says 4L. Cannot change any buttons. When I do, they blink then stays on 4L. Trans seems to change shift patterns, goes into 1-4 gears quickly and lock-up by 35mph. I have to manually shift trans when 4x4 lights go wierd and service 4x4 light is on, otherwise trans goes into a sort of safemode. I was told by dealership to replace selector buttons on dash, but no luck. P1875 code came up. No help.
Thursday, November 18th, 2010 AT 2:32 AM