Another 4wd post 4hi problem

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drakon543

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sorry for the long post.

ok so i did some forum searching and google searching on my problem to start. so my problem is 4lo locks in fine and locks the front axle. when i hit the button for 4 hi it blinks and just goes back out. i haven't triggered it yet to blink any codes back to me ill do that in these next 3 days. last year i had no 4wd as the front actuator was shorted and kept blowing the fuse. i replaced that with the gm upgrade to ditch the thermo switch for faster axle engagement. so the one relating issue i found was tied to the transfer case sensor/switches. specifically the one that tells it that it successfully shifted into 4hi. so i tried to do some more digging on that rockauto lists 2 switch sensors for the transfer case relating to that. both of them look identical and they both have a 2 pin and 3 pin versions. does anyone have a breakdown of the pushbutton transfer case that clearly indicates where all the electronics are located on the transfer case and what each one does. also if i have the door open when i push 4hi i can hear the motor shifting the tranfer case but it immediately shifts it back. ive googled for a transfer case breakdown a few times and found some good ones but they aren't tied to the other half of the image that tells me what it is.
 

HiHoeSilver

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sorry for the long post.

ok so i did some forum searching and google searching on my problem to start. so my problem is 4lo locks in fine and locks the front axle. when i hit the button for 4 hi it blinks and just goes back out. i haven't triggered it yet to blink any codes back to me ill do that in these next 3 days. last year i had no 4wd as the front actuator was shorted and kept blowing the fuse. i replaced that with the gm upgrade to ditch the thermo switch for faster axle engagement. so the one relating issue i found was tied to the transfer case sensor/switches. specifically the one that tells it that it successfully shifted into 4hi. so i tried to do some more digging on that rockauto lists 2 switch sensors for the transfer case relating to that. both of them look identical and they both have a 2 pin and 3 pin versions. does anyone have a breakdown of the pushbutton transfer case that clearly indicates where all the electronics are located on the transfer case and what each one does. also if i have the door open when i push 4hi i can hear the motor shifting the tranfer case but it immediately shifts it back. ive googled for a transfer case breakdown a few times and found some good ones but they aren't tied to the other half of the image that tells me what it is.

I know this is not what you're after and it sure sounds like you're farther along than this, but are you following the instructions from the manual on getting in /out of 4lo? iirc, there's a little more to it than simply hitting the button. Have you tried it at a slight roll?
 
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drakon543

drakon543

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ya its with me going from 2 to 4hi. getting it back out of 4lo can be difficult as it will shift back to 4lo a few times before i manage to get it back into 2hi
 

Sean James

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I had a similar issue, it was the stupid $30 switch on the dash. Autozone has them because they must be a common issue. Took me 5 minutes to pop out the old switch and install the new one. Fixed the problem immediatly! Tahoe would go from 2hi to 4hi and when stopped to 4low or auto all by itself. I would push the switch to change from one to another and it would have a mind of it's own.
 

Sean James

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OOpps, the switch was $59 at auto-zone, make sure you get the right one. I had a rpo code in the glove box that was "NP8", and autozone had one just for that particular RPO code.
 

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