timrob

I checked the owners manual and it does list a procedure for getting the transfer case into neutral. It said you have to be parked, parking brake set, trans in neutral, and hold 2 buttons for 10 seconds. I was able to get the transfer case into neutral. The service manual did not say anything about rolling/moving. I mostly took apart the 4WD switch. I did notice some dirt or something on the button contacts. I'll clean those up, compeletly take apart the switch and resolder. Aaron, you can either cycle the ignition, pull the TREC fuse, or disconnect the battery to reset the system. This will temporarily fix the problem, at least it does for my truck.

On the switch panel, if you push 2hi and 4lo at the same time, the transfer case be put into neutral. The graphic on the panel shows a line between those 2 buttons. Last night, I tried to get the transfer case into neutral using the 2 button method, but was unable. I'll look at the owners manual tonight. This would explain everything but the U codes, but those could have been previously set. From another website "As far as the transfer case is concerned, when the neutral condition occurs, does the indicator show neutral? To electronically shift into neutral requires simultaneously pressing 2hi and 4lo. This specific resistance value(or volt drop) is interpreted by the module, and corresponds to the selected range output."

I've been having increasing problems for a few weeks with the 4WD. I would be driving along in Auto 4WD and I would receive the message "Check 4WD..." on the DIC. The transfer case would make growling sounds when this happens. I would stop the truck, cycle the ignition, and the problem would go away. It's done this for several years, but it would rarely happen. Now it's happening many times a day, but cycling the ignition still fixes the issue. I'm aware of the switch and encoder problems and will look into that. Coincidentally or not, I also had a transmission issue on Sunday, about an hour after the Michigan snow/ice storm started. I don't know if it's related or not. Driving along the freeway about 30MPH because of the snow buildup, the transmission disengages, just like I'm in neutral. I coast to the side of the freeway, turn the ignition off, wait for 5 minutes, and the transmission is fine. About 10 minutes before this, the 4WD switch panel has the red LED and none of the 4WD buttons will work. I'm stuck in 2WD. Cycling the ignition does not fix the 4WD. So I drive about 1 mile in 2WD and the trans disengages again. I cycle the ignition, wait about 10 minutes and the trans works again. I repeat the process 4 or 5 times till I get off the freeway. At this point, cars are spinning out and crashing left and right. I get off the freeway and wait for 3 hours for a tow truck. I try to engage the transmission again during the 3 hour wait with no luck. I've never had a transmission problem before this. The dealer reports the the transmission had a bunch of Class 2 U codes, network codes. The Transfer Case had a Encoder Motor sensor error. Trans fluid was filled, red, and not burnt. The dealer could not duplicate the transmission issue. Tuffy flushed the transmission and added new fluid 1 year ago at 110,000 miles. The encoder motor connector voltage and resistance was checked and ok. After the Dealer cleared the codes, everything has been working fine for a couple of days. Now my questions. 1. If the transfer case is acting wacky, either by a bad switch, encoder motor, loose ground, whatever, should rear wheel drive still work? Is RWD dependant on the transfer case? I know the drive shaft is connected to the transfer case. 2. When a GM vehicle with Class 2 has a communication error, will the transmission still work? This is not the "reduced power mode" also known as "limp home mode" as the trans was completely disengaged. Sorry for the long explanation, but I don't want to be stranded or throw a bunch of parts at it. 2003 Silverado, 124,000 miles, Z71, 5.3L, 4 speed automatic, 4WD push button