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Help, 4x4 not engaging

thefox1

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thefox1 Enthusiast

thefox1

Posted
Posted

I have a 99 GMC Yukon 5.3l with an automatic transfer case. A couple of weeks ago I had the seals on the front wheels that go into the diff. changed, and since then the 4x4 no longer engages. Could the replacement of theses leaking seals cause my problem?

Ape0r Enthusiast

Ape0r

Posted
Posted
I have a 99 GMC Yukon 5.3l with an automatic transfer case. A couple of weeks ago I had the seals on the front wheels that go into the diff. changed, and since then the 4x4 no longer engages. Could the replacement of theses leaking seals cause my problem?

 

 

 

 

Did the mechanic remember to plug back in all the connectors he took out? =). Do the LED indicators on your switch do anything funny? These switches are known for failure, could be coincidence.

crazymjb Enthusiast

crazymjb

Posted
Posted

The only thing I could think of is that it has to be locked in 4WD during the procedure(or the diff falls apart and you gotta open it up), so maybe they screwed it up then.

 

I don't mean to hijack the thread... But I heard with pushbuttons systems from 4HI to 4LOW, and VV, the truck has to be in Neutral. Can anyone confirm this? Also, will it allow you to change between the two when in drive, or does it have a neutral safety switch(if that is the case)?

 

Thanks,

 

Mike

thefox1 Enthusiast

thefox1

Posted
  • Author
Posted
The only thing I could think of is that it has to be locked in 4WD during the procedure(or the diff falls apart and you gotta open it up), so maybe they screwed it up then.

 

I don't mean to hijack the thread... But I heard with pushbuttons systems from 4HI to 4LOW, and VV, the truck has to be in Neutral. Can anyone confirm this? Also, will it allow you to change between the two when in drive, or does it have a neutral safety switch(if that is the case)?

 

Thanks,

 

Mike

 

 

 

 

 

Yes, to go from 4Hi (or 2Hi) to 4Lo, you have to be in neutral.

Ape0r Enthusiast

Ape0r

Posted
Posted
The only thing I could think of is that it has to be locked in 4WD during the procedure(or the diff falls apart and you gotta open it up), so maybe they screwed it up then.

 

I don't mean to hijack the thread... But I heard with pushbuttons systems from 4HI to 4LOW, and VV, the truck has to be in Neutral. Can anyone confirm this? Also, will it allow you to change between the two when in drive, or does it have a neutral safety switch(if that is the case)?

 

Thanks,

 

Mike

 

 

 

 

This is correct. The truck must be in neutral to shift into 4-LO. I worked at chevy dealer last summer.. had a guy bring in a gorgeous 2500HD D/A because he couldn't be bothered to read his manual when it wouldn't shift into 4-LO. Oh well, didn't mind cruising around in it for a few minutes!

crazymjb Enthusiast

crazymjb

Posted
Posted

Does it require you to be in nuetral before it will even function(planetary gearset, correct?), or can I mechanically desacrate the system by hitting the button(in which case I will put a new set of buttons in with shields)? Also, how much reduction is offered in 4LO?

 

Mike

Ape0r Enthusiast

Ape0r

Posted
Posted
Does it require you to be in nuetral before it will even function(planetary gearset, correct?), or can I mechanically desacrate the system by hitting the button(in which case I will put a new set of buttons in with shields)? Also, how much reduction is offered in 4LO?

 

Mike

 

 

 

 

If you try to shift into 4-LO without the trans in neutral the lights will just blink at you and be like :cheers:.

 

4-LO gives a 2.72:1 reduction.

 

4-Lo + First gear + 3.73 rear = 2.72*3.06*3.73 = 31.05:1 overall reduction :P.

 

Just imagine what that does at the wheels when the engine is cranking out its peak torque at the flywheel! If you want to find out stick it in 4-lo and floor that sucker!.. but be sure your head is against the headrest first..

crazymjb Enthusiast

crazymjb

Posted
Posted

And I got the 350 In there(In 2Hi can one spin the tires with an empty bed?) :cheers:

 

I am hesitant to screw around with the engine because its got 80K on it and is working flawlessly.

 

BTW, I should have it registered and in my driveway by friday, I am so excited :P

 

Thanks,

 

Mike

thefox1 Enthusiast

thefox1

Posted
  • Author
Posted
And I got the 350 In there(In 2Hi can one spin the tires with an empty bed?) :cheers:

 

I am hesitant to screw around with the engine because its got 80K on it and is working flawlessly.

 

BTW, I should have it registered and in my driveway by friday, I am so excited :P

 

Thanks,

 

Mike

 

 

 

 

 

As long as you don't do what my buddy did. He put the pedal to the floor in snow with the steering completly turned to the right, then shifted it in reverse at 2500rpm. Bye bye tranny!!

  • 8 months later...
Zeppelin264 Enthusiast

Zeppelin264

Posted
Posted

Hi, i know this post is old but did you ever deicde what the deal was with the seals and the 4x4 not engaging?

 

i recently did this and have the same problem and im wondering if you have to be locked in to make sure the diff dosent fall apart.

 

Thanks

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