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Discussion Starter · #1 ·
My suburban is stuck in 4 Lo and won't come out. When I parked it last, it was in 2 Hi. When I started it this morning, the 4 Lo light was lit and it won't come out. When I put the truck in Neutral there's a faint growling from what I assume is the transfer case. Longer than what I would expect the shift motor to take to change from 4 Lo.

I have read some other posts here and I think I'll try again with the transmission in neutral and the switch ON, but not running.

I'm at a loss. Over this summer the transfer case voluntarily shifted from 2 Hi to N while I was in a parking lot. I took it to a local shop who replaced the shift motor on the transfer case. Now I'm back to shift problems. If I could move it, I'd take it back to the shop again.

Any insight would be appreciated.

Dave
 

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2001 Suburban 5.3L, 296k miles
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My suburban is stuck in 4 Lo and won't come out. When I parked it last, it was in 2 Hi. When I started it this morning, the 4 Lo light was lit and it won't come out. When I put the truck in Neutral there's a faint growling from what I assume is the transfer case. Longer than what I would expect the shift motor to take to change from 4 Lo.



I'm at a loss. Over this summer the transfer case voluntarily shifted from 2 Hi to N while I was in a parking lot. I took it to a local shop who replaced the shift motor on the transfer case. Now I'm back to shift problems. If I could move it, I'd take it back to the shop again.

Any insight would be appreciated.

Dave

Well, the encoder motor has an electric brake to lock it in the shift range that was selected. The only way it will change to another shift range is if the motor brake loses power or if the transfer case module is being commanded to shift.
1. Check that the encoder motor brake is supplied power by the transfer case fuse.
2. The transfer case module is always waiting for any an input signal from the dash switches. The dash switches are just momentary switches. So check that the switches are not sending any false signal voltage to the module.
 
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Discussion Starter · #3 ·
Thanks for the response @bazar01 . I got it back to 2Hi with the truck in N, rolling slightly and the switch on not running. I'm headed back to the shop with it.

I will have to digest all of what you shared above to be sure I understand it correctly. I'll also share this with the shop, although if he's any good he should already know. He's a new guy to me, but I understand he came from the local GM dealership shop.

Thanks again. I appreciate the expertise that this group has and shares.
 

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Great you got in 2Hi. So the encoder motor is good then.
Check the fluid level and condition first before you do anything.

Do you see any trace of fluid outside the case close to the output towards the drive shaft? These transfer cases are known for the lube pump housing thin tabs wearing in on the case causing loss of fluid.
 

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Discussion Starter · #5 ·
Roger that. Some history I didn't share... The transfer case was EMPTY when I bought the suburban. I replaced the entire case with one from a 1500 and swapped the input (or was it output) shaft to match the K2500. I put a pump rub plate in at that time and topped it off. That was maybe 5k miles ago? I've been trouble shooting this thing since then. It would nearly always start in AUTO, but push the button and it compliantly went to 2HI. This summer it shifted to N at low speed two or three times. That's what finally sent me to the shop where the guy replaced the encoder motor on the transfer case. The one thing I hadn't tried yet. I had previously cleaned the grounds under the driver's feet, tried new switches (from a similar truck), tried a new computer (from a similar truck) and replaced the front end actuator.

It was great after the new encoder motor... for a few weeks. Occasionally on start-up the push button light wasn't lit in any position. After 30 seconds it would light on 2HI. The issue above came this week with the transfer case sent to 4LO for no apparent reason. With as much trouble as I had getting it out of 4LO, I am surprised it went in without notice.

Thinking on this more now, I will replace the dash switches. I tried my buddies switches in my truck once before when it always started in AUTO, but that didn't seem to fix that problem so I put mine back in. I'll spring the few bucks and do it now. I'll report back what happens.

Thanks again for the guidance.
 

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Discussion Starter · #6 ·
UPDATE:

I put a new switch in the dash and it's been working fine since. Only a few trips on the new switch, but it starts in 2 HI every time, I listened to it engage the front in AUTO and I heard and felt it engage 4HI when pushed. I am hopeful that I'm fixed. I will certainly monitor for a while longer and report back if anything changes. No news here means good news...
 

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Discussion Starter · #7 ·
Final post here. The 'burban's been fine since putting the new switch in the dash. I am embarrassed that it was such a simple fix and I spent many hours and dollars going around in the wrong direction. I've called for 4 HI a couple times here during hunting season and it's been reliable going in and out of 4 HI. I call this fixed. Thanks for the input.
 
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