2001 Chevy Suburban stuck in 4 wheel LO


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Old 11-01-09, 12:39 AM
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2001 Chevy Suburban stuck in 4 wheel LO

My 16 yo new driver backed over a friends mailbox and metal pole. The pole wedged under the rear bumper he says, but took a lot of prying to release. He says the pole was laying against the spare tire and probably other parts of the undercarriage. He freed vehicle then drove off.
Car is stuck in 4 wheel low when driven, and a slight rythmic screech is heard only when the car is moving in a forward direction.
It was dark out when this happened. Will be able to get under in the morning. Any suggestions as to what to look for, and how to disengage 4 wheel lo.
Thanks,
Dave
 
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Old 11-01-09, 04:32 AM
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Not sure what damage could have happened at the rear of the vehicle, only, since the transfer case and controls to the axles are in the front. If the post was run over from the front (as opposed to being backed over), then damage could have occurred to the vacuum hoses and/or electrical connections at the transfer case. I am assuming it is and electrical engagement as opposed to a manual engagement setup. Check up closer to the transfer case for damage to the undercarriage, wiring or hoses. I believe you will find something there. Let us know.
 
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Old 11-01-09, 08:45 AM
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Undercarriage looksfine. No evidece of physical damage. Just can't get out of 4 wheel Lo no matter what button I push. What do you suggest?
Thanks
 
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Old 11-01-09, 09:00 AM
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There is no vacuum hose on a GM transfer case.

The 4L60E transmission is electric shift and the transfer case has a encoder motor that shifts the transfer case in and out of 4 wheel drive.

It's all ran by computer and electricity, no more shifters - unless it does not have Autotrac and even then the shifter is not directly connected to the inner workings of the transfer case.

Time to take it to a transmission shop or a GM garage.
 
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Old 11-02-09, 08:24 AM
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i supose you have tried this,
start the unit up
place shifter in Neutral
now select 2hi.
 
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Old 11-02-09, 09:17 AM
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Originally Posted by DIRTWRKZ View Post
i supose you have tried this,
start the unit up
place shifter in Neutral
now select 2hi.
put trans in neutral,& 'put foot on brake'
 
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Old 11-02-09, 03:01 PM
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If you go over to the Chevy Avalanche Fan Club forum, there is many people there that can help you.

The transfer case is electric shift.

When you have a problem with the transfer case - which when you add a 8 year old vehicle and a 16 year old kid - it will usually equal double trouble.

There is a technical side to the transfer case, where there is fluid inside of there that has to be changed at regular intervals and also a encoder motor that shifts the transfer case in and out of four wheel drive.

The days of direct drive gears inside of a transfer case is long gone.

There is a set of clutches that looks similar to the clutches found inside of a old TH 400 transmission and a lot of things that requires a certain amount of clearance to work properly.

When ever any of those clutches or other parts wears and gets out of specifications, you will have problems.

Haynes does not even have a section in their repair manual for the transfer case due to the fact that it takes many special tools to take it apart and even more specialized tools to replace all the bearings and the retainers and the races and by the time you bought all the tools, you could buy several transfer cases.

Take it to a garage, have them diagnose the problem, have them give you a written estimate of how much it will cost to repair, then you can decide if you want to buy a good used unit or if you wish to buy a re manufactured unit from GM = probably $1000+ or if you wanted to send your unit to a transmission shop and have it rebuilt.

The first problem is sometimes something as simple as a bad switch in the dash board. Or a bad relay or a bad fuse. But usually the module on the side of the transfer case that shifts it in and out of four wheel drive is what goes bad first.

If it has over 100,000 miles and you never changed the transfer case oil, chances are the unit might be burned up and needs to be replaced.

I believe I paid $12 a quart for the fluid the last time I changed mine and I believe that it took just a little over 1 quart to refill it. The fluid is green and it pours like water.
 
 

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