Stuck in 4WD

Boomer

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#1
Make
Chevrolet
Model
S10
Year
2002
Miles
144000
Engine
4.3
2002 S10 4x4 ZR-2 4.3 144,000 miles. This morning I backed out of the garage and went to enter the street and I could feel the familiar pull of 4WD. Weird thing is, I haven’t put it in 4 wheel since winter. I tried pushing the button to go back to 2 wheel and nothing happens. No light blink. Nothing. Stays in 4Hi. I’m guessing possibly encoder motor?
 
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#2
your sure its the TC?
Sometimes the TC gets torque locked, shifting to N stopping completely then R might unload the TC.
What happens if you select 4lo?
 

Boomer

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#3
your sure its the TC?
Sometimes the TC gets torque locked, shifting to N stopping completely then R might unload the TC.
What happens if you select 4lo?
I’m not sure about anything currently. I had to go to work so I just jumped in my other truck. As soon as I can (maybe late tonight) I will try your suggestions. I’d love for it to be simple. I’m just a little puzzled how it got into 4 wheel drive
 

grcauto

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#4
your sure its the TC?
Sometimes the TC gets torque locked, shifting to N stopping completely then R might unload the TC.
What happens if you select 4lo?
I don't know how you ask about the TC when he never mentioned it......
2002 S10 4x4 ZR-2 4.3 144,000 miles. This morning I backed out of the garage and went to enter the street and I could feel the familiar pull of 4WD. Weird thing is, I haven’t put it in 4 wheel since winter. I tried pushing the button to go back to 2 wheel and nothing happens. No light blink. Nothing. Stays in 4Hi. I’m guessing possibly encoder motor?
I would start by checking the encoder. It's the logical place to start. Nice if you have an enhanced scan tool.
 

Boomer

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#5
Ok, I got home and tried messing around like Kev suggested. At first, nothing was happening. Finally, I held the 2Hi button and managed to get it to switch. I started driving and it went back to 4hi. I ended up getting it to go back into 2 wheel again and drove around a little bit and it stayed there. I guess I'll see if it stays there in the coming days. I can't help but feel this is a warning sign that something is going haywire.

My scan tool is not bi-directional. It's an Actron CP9580A. Hopefully there are ways to troubleshoot it without an expensive tool. I'm a DIYer not a pro mechanic. I'm good with electrical though so I should be able to check some things out. Since it's just spring, I'd be happy if it stayed in 2WD. That would give me plenty of time to fix it before I'll need 4 wheel again.
 

Boomer

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#6
While driving to work once I noticed the 4Hi light back on. I couldn't tell if it was really in 4WD or the light was just lit up. Considering when it happened before it was in 4 wheel, I'm gonna guess it probably was. I got it back in 2 wheel by holding the button for a second. The next work trip, it stayed in 2WD. It's an intermittent problem for now it seems.
 
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#8
I first took TC to mean "torque converter" but then realized you meant "transfer case". Your use of the words "torque locked" took my brain down the wrong path. I'll bet that is what happened to grcauto. But "torque locked" is a great way to describe the problem of the parts being too bound up to shift to another function.
 

Boomer

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#9
Im still not sure what’s allowing it to change to 4 wheel by itself.
 

Boomer

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#10
Im still not sure what’s allowing it to change to 4 wheel by itself.
Drove home from work and turned into the driveway. Felt like I lost power steering. Sure enough, it was in 4WD. Do you guys think the encoder motor is weak and causing this? Any troubleshooting trees maybe?
 
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#11
I suggest that you get it into 2WD and the disconnect the encoder motor wires and see if the transfer case remains in 2WD for (x) miles or days.
 

Boomer

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#12
I suggest that you get it into 2WD and the disconnect the encoder motor wires and see if the transfer case remains in 2WD for (x) miles or days.
That's a great idea Dan. I've just noticed I'm leaking what appears to be trans fluid. I'm hoping it's just the pan gasket and not something worse.
 
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#13
quick question have you looked for codes ?

There may be a clue there, the codes are likely 'B' series so a good scanner needed, Dans idea is a good check BUT scan first,

Hope thought is not to late.
 

Boomer

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#14
quick question have you looked for codes ?

There may be a clue there, the codes are likely 'B' series so a good scanner needed, Dans idea is a good check BUT scan first,

Hope thought is not to late.
I haven’t seen the light come on so I have not. To the best of my knowledge my Actron scanner has been ok at retrieving codes. I can check it. Maybe I need to go with a Bluetooth option? I know Nickb2 talked to me about that a couple of years ago