01 s-10 stuck in 4hi

Hi guys, this is what I know... I have a NP1 transfer case. The control switch is always showing 4hi. if I hit 2hi, it flashes a few times then stays on 4hi, same with 4l. When I do this I hear clicking from the TCCM on the pass side. There are no codes in memory. I've already replaced the vacuum control switch with the updated switch(vacuum lines were full of tranny fluid). I have the GM service manual but as hard as I look, I can't find this specific problem. The no codes is the part that throws me, I'd like to know where to look next. Thanks for your time

What all push buttons does it have?
The transfer case id is on the rear of transfer case.
What one do you have?
If a 233 transfer case you can ground pin 13 on diagnostic plugin and get codes.
Post back any codes.
If the auto matic 4W you will need a transfer case capable scanner to get codes or test it.
MT

thanks for the reply. yes, it is the 233 transfer case. grounding pin 13 gives no flashes which means no codes. I have 2H, 4H, and 4L switches. The no codes part is what puzzles me.

Did you check the shift button lights for flashes or check engine light?
Does the shift button light come on for a bulb check key on?
Did they bulb check on the code check or do anything?
MT

Hi guys, this is what I know... I have a NP1 transfer case. The control switch is always showing 4hi. if I hit 2hi, it flashes a few times then stays on 4hi, same with 4l. When I do this I hear clicking from the TCCM on the pass side. There are no codes in memory. I've already replaced the vacuum control switch with the updated switch(vacuum lines were full of tranny fluid). I have the GM service manual but as hard as I look, I can't find this specific problem. The no codes is the part that throws me, I'd like to know where to look next. Thanks for your time

did you find fluid in lines now . fluid came from transfercase.

mt-2500... thanks for the reply. All lights come on for key on bulb check. i was watching the shift buttons, not the engine light. no bulb check or any flashes when i ground pin 13.
j cat... nope. tranny fluid all gone. the switch was faulty. GM came out with an upgrade.