4X4 shifting??

[billnourse]

My sister has a 2001 Suburban that won't shift into 4 wheel drive. When the buttons are pushed they blink then go back to 2 WD. After several trys it will finally work. This problem is more pronounced when the vehicle is cold. Dealer says everything is normal. This vheicle is a 6.0 Auto, with the automatic 4x4 option.

Any help or information will be appreciated.

Thanks,

Bill

[dmaxalliTech]

Bill, chances are that when the system malfunctioned, it would have stored a DTC. Dealer would retrieve this using the Tech-2 and looking under ATC DTC information. There is likely to be a code stored (B2725) for a transfer case shift select switch malfunction. There may also be failure with the encoder motor mounted on the transfer case. It is very rare anymore to see troubles with the front axle actuator now that they have gone to the electic unit. When it is acting up, try and listen for a motor noise from the transfer case area, see if the encoder is working or not, if its not making noise when lights are blinking, chances point to switch,. If its making noise, chances are encoder is confused and its not sure where to go. It may be better to 'hear' the motor with the truck off, just put the key to run, you also might want to try it in neutral cycling into 4 low also. Hope this helps

[NickLeinonen]

hmm. kinda sounds like a bad ground to the front differential actuator...

[turbowind]

Hi Guys !
My 2003 CC DMA 4x4 has a similar problem...the transfer swift panel lights all light up, then go out, the service 4 wheel Drive light message comes up and I get an a "thunk" from the transfer case area. The code shows encoder motor fail...They have re-flashed the OBC with an update , that worked for about a day. The dealer has ordered a new encoder motor with an unknown delivery date, and a note that this problem may not be fixed by a encoder change...Seems this is a known problem and no fix has been found.

Les

[DMaxCaptain]

This is a problem that I have had on my 2003 since day one. @ encoder changes and 1 transfer case motor change with no help. The latest is that GM says that there is a software glitch and a software fix is coming (sometime, so far it has been 3 month coming...)