Service 4wd help

[Hink]

Ive been dealing with an intermittent 4wd issue for a while now and i want to try to actually fix it this winter lol. i have a service 4wd message and the only code it threw was a gm code 42 which i wouldnt think is related to the 4wd, or is it?? Ive been seeing the typical red neutral light from no light at all, as well as it being stuck in 2 high and not able to change out of it, and also the occassional 4 low light. Seems to work fine if i try to change into 4 hi or low before the service 4wd message pops up. i used 4 high the other day and its been worse since then, the lights wouldnt come on at all for a week afterwards ( they do light while starting the vehicle). Seems stuck in 2 high at the moment. i replaced the dash switch and trouble still persists. i hate the thought of throwing parts at it but it may come to that. From what i gather it could be the encoder ring in the transfer case motor or the transfer case control module, or heck it could be both or neither with my luck lol.

What should be my first plan of attack here? Any suggestions?

 

[Tonyrodz]

Back in 2012, I had the service 4wd pop up. I don't remember if any of the lights lit up in the 4wd buttons tho. Turned out it was one of the front axles. Boot was torn and was slinging grease. Changed the axle and no more service 4wd. Did you look underneath and check your axle boots? You might luck out.

 

[Z28TWITCH]

Code 42? What year is the truck? My 4wd has always been touchy. Had similar problems with mine and ended up throwing a new encoder motor and the front axle 4x4 actuator. Both were really easy jobs in the driveway. Truck goes in and out of 4hi real easy, 4lo is still touchy but hey, I RARELY use 4lo so Ill take a win where I can get it. Dont forget to get some new AutotrakII and change it out. Tcase only takes two quarts, real easy with a bottle pump. Good luck.

 

[ATIII]

Have your transfer case encoder motor and sensor checked out. Very common problem. I let mine go for too long ended up costing me $1100 to replace the motor, sensor and a shift fork in the Transfer Case.


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[Hink]

Tahoe is an 04, Z71 with 170k on it.

Thanks for the replies fellas, i appreciate it.