4x4 Won't Disengage from 4hi to 2hi while driving.

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RHamill

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Truck: 1996 Chevy K1500
Transfercase: NP243 (New Process) Button Actuated

Upgrades: Updated Electric Actuator, New Transfercase Switch

Problem: Truck won't disengage from 4hi to 2hi while in motion, unless stopped, put in reverse, roll 5 feet, then put back in drive.

What is my problem??

TCCM? Buttons? Encoder Motor?

Buttons are $48 bucks, encoder motor is $157, TCCM I'm not sure of cost.
 
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JParker2012

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I wish I could help but I have no clue about the electronic 4wd shifting mechanism. Iv always delt with the manual shifting levers that link up to the auto engaging hubs and transfer case. have you tryd using an error code reader on it to trouble shoot it? the plugin is just under the dash and I figure since the electronic 4wd buttons use the computer interface to work maybe they would show an error code if broken.... :shrug:
 

RHamill

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I wish I could help but I have no clue about the electronic 4wd shifting mechanism. Iv always delt with the manual shifting levers that link up to the auto engaging hubs and transfer case. have you tryd using an error code reader on it to trouble shoot it? the plugin is just under the dash and I figure since the electronic 4wd buttons use the computer interface to work maybe they would show an error code if broken.... :shrug:

I know all about OBII scanning, we have a GM Tech II scanner at work that will tell you every bit of information, in fact I just plugged it in friday to recheck my already on engine light just to make sure the codes were still just the lean o2 sensors (which rears arent plugged in because I have no cats). Everything was fine.

My mom has a 97 with the 243 transfer case, so I will be pulling her buttons out and putting them in my truck to diagnose the problem.
 

badazzbulldog

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Electric Actuator sticking? with the scanner you can run tests on the switch and the encoder motor,but to me it sounds like the actuator sticking cause it disengages when stopped
 

RHamill

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Electric Actuator sticking? with the scanner you can run tests on the switch and the encoder motor,but to me it sounds like the actuator sticking cause it disengages when stopped

Would putting silicone grease on the metal piece that you slide in the front diff with the actuator help any?
 

RHamill

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I'm not sure how to get that piece out of the diff? I took the actuator out, cleaned it, put it back in and tightened it pretty good, and it seems like the 4hi is disengaging more often when at slow speeds, I was climbing the mini dune in my back 40 and I heard from someone that if you tap the brake pedal the same time you press 2hi, it helps it disengage, and it worked. But still when cruising at 60 mph in 4hi, I should be able to immediately disengage to 2hi shouldnt I?

EDIT: I just thought of using a high powered magnet to get that piece out.
 

badazzbulldog

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well i know on my truck which has the floor shift,if i'm out plowing and switch from 4 to 2 while driving i back off the gas pedal and it will disengage and thats in the 30mph range and it takes a few seconds to kick out and there have been times it would stay in till i came to a stop and accelerated again then it kicked out,i think too outside temp has an effect on how fast it moves
 

Farmerdan91

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Some older trucks you have to put it in reverse to unlock the 4X4, its not a transfer case problem and if theres somethin else wrong id probably change the transfer case oil with 3 quarts of tanny fluid and clean out the metal shavings in it.
 
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