4x4 issues.

[DJ4180]

Hello once again guys. So today I realized I may not actually have a working 4x4 system. The other day in the snow I was in 4hi and put in reverse and backed up the way it should. It actually left ruts where the front tires were where you could see the front tires dig down to the cement in the parking lot. Although today in about seven inches of snow in the same parking lot I noticed a loss in traction. A purposely pulled into the fresh snow at the end of the lot and hung my head out the window and hit the gas. The front drivers side tire did not spin and I sat there spinning the back tires. I eventually got it "unstuck" with a little rocking and continues through with no problems. The lights on my 4x4 indicator switch have never fully worked. They seem really dim sometimes and sometimes while driving they get real bright. I have pulled the dash off and plugged them in a little better without helping thay problem. So im not sure if the switch is just bad. Someone also toltold me when engaging 4x4 it will clunk almost when it engages. And it has never done thay. I hear am the switch click and that's it. Any suggestions. Can it be the switch or is it something under the hood. Any suggestons would help. Thanks. Also it is a 99 tahoe LS

 

[lesterl]

There are several things that happen to engage the 4x4, first you have a shift of gears/ clutches in the transfer case, you have the front end lock into gear, and it is controlled from a module under the dash, hooked up to an interface ON your dash.

 

[DJ4180]

Just not sure what if anything isn't working. As I said it seemed to work great and then today didn't. We have alot of snow coming in the next 2 days and just wanted to get this hashed out. Thanks though

 

[lesterl]

If you start it up, drop it into 4x4 does the front shaft turn by hand? Jack up front end, chock rear wheels, do both front wheels rotate when one is turned?

 

[Ice98]

unless you somehow have had a limited slip installed on the front, the same will happen in any situation, one wheel will spin while the other stays stuck if one has some traction and the other has none...

best test would be to put the whole truck up off the ground on jack stands with the 4wd engaged, start it up and put it in gear, all the wheels should begin to rotate

 

[DJ4180]

Thank to u ice for your input. I will try that tommorrow if the weather isn't too bad as I am at work right now. But if I am understanding you right you are saying that is how it is suppose to work. Only the one that is slipping should spin when 4x4 is engaged?

 

[Ice98]

Thank to u ice for your input. I will try that tommorrow if the weather isn't too bad as I am at work right now. But if I am understanding you right you are saying that is how it is suppose to work. Only the one that is slipping should spin when 4x4 is engaged?

Without a limited slip differential if you were to hold one wheel tight with nothing on the other (IE, having one wheel stuck and the other free) then all the power just goes to the wheel that has no traction and that wheel spins uselessly

https://www.youtube.com/watch?v=-dh0VQxprJA

Skip to the 2 minute mark or so and it explains what happens when you lose traction on one wheel on each axle, without a locking differential or limited slip diff you cannot really avoid the spinning wheel parable, 4wd will always give you better traction than 2, but it is still a system with limitations

 

[DJ4180]

Thank you again sir. I guess I just need to figure out which one I have on my tahoe. But that makes more sense. Even on my way to work today I could tell it was working when driving up the mountain. But im assuming whatever is stock on my tahoe only allows the slipping wheel to spin. Thanks again for your help. It is greatly appreciated

 

[Ice98]

Thank you again sir. I guess I just need to figure out which one I have on my tahoe. But that makes more sense. Even on my way to work today I could tell it was working when driving up the mountain. But im assuming whatever is stock on my tahoe only allows the slipping wheel to spin. Thanks again for your help. It is greatly appreciated

You should definitely feel the difference when 4WD is engaged, the steering feels quite a bit different

 

[lesterl]

Front probably does not have a LSD.... Even with a LSD in my experience you will still one wheel peel most of the time..... With front end locked, it should feel like the front end binding up when turning....

 

[Ruthless]

Any update on this? My 4wd is also giving me problems. I bought it several months ago with a bad transfer case actuator. Finally replaced that and now it is shifting properly and it goes into 4lo and i get the reduced gearing however its like i have no power to the front wheels at all. I jacked up the rear end with it in 4wd and the back tires spin but the front did not. I'm mind boggled at this point. And just to make things worse when i first replaced the actuator it worked with all four tires off the ground then i lowered it and went into the back yard to play a little and give it a try and got stuck... talk about a long walk back to the house to get the other truck and my wife.:whymewhyme:

 

[lesterl]

Check the actuator in the front diff ..

 

[Ruthless]

But the whole front drive shaft isn't turning at all while the back one does. And also how would I go about checking the front actuator? Is it one or two?

 

[Ice98]

https://www.youtube.com/watch?v=JpHn9gRXVXw

 

[lesterl]

Looks easy, 2 min job..... that was quick.....

 

[Ice98]

Looks easy, 2 min job..... that was quick.....

Super easy


I have a decent clunk when my 4wd engages, hopefully that's not bad