The service 4wd light is much like the check engine light. When it is on, codes have been stored in the TCCM. You need to have your TCCM scanned by a GM Tech2 or equivalent full feature scan tool to know what the TCCM has reported as being the source of the problem.

 

could be the sensor on the front axle is faulty as well had that happen before replaced that and it stopped doing that.

 

could it just be the tccm?
or the actuator?

 

Get the codes read and go from there.

 

i've seen them sensors fail more than once. get locked in 4wd and you cant get out

 

like swartlkk was saying get those codes read first. if your having problems disengage best bet is that front sensor, i believe its on the diff. have you ever had problems getting 4wd to engage? those actuator/motors are usally at fault when you cant get into 4wd. that was the case on mine

 

its not that it wont disingage is that as soon as my service 4wd light comes on i hear a click in the tccm and then the buttons are like froze
when i hit a botton on the dash to try and switch from 4wd to 2wd or vise versa it will just stay how it is until i discontect my battery and reconect it and it resets everything

 

almost sounds like your actuator is getting stuck in between 4wd & 2hi which is kinda weird. never seen that before. get those codes scan and then that will make diagnosing it alot easier

 

how much does it cost to get the codes scanned?

 

where im from (MI) we have autozones that scan for free i dont know if you have autopart places like that or not that scan for free