The rare AWD Tahoe and some questions.

[01ssreda4]

Yep you sure can, at least in the rear. Im not super familiar with the IFS front diffs in these trucks.

 

[TTro33]

Ahhh, now my wife says the brakes are doing the ABS stuttering thing and it has never done that, and I haven't touched it since I replaced the bearings. Not to mention the rear flap that changes hot and cold is broken. I don't have enough time but I'm too stubborn to pay anyone.

 

[TTro33]

Never mind I think she just means shaking when braking, I think I will have all 4 rotors turned.

 

[W8TVI]

On an all wheel drive its perfectly normal for the truck to roll around if the front wheels come off the ground(or if an axle/driveshaft is removed too). The AWD trucks run 3 open differentials. Front, Center and rear. With the front wheels off the ground there is no resistance in the drive train and the open differential in the trasnfercase allows the back wheels to roll. the front wheels or wheel should turn the same amount as the rears. just like when you jack up the rear on an open diff and spin one tire forwards the other spins backwards the same distance.

The locking mechanism for park is internal in the transmission, thats upstream of the transfercase. upstream of where the "slip" is happening when a wheel is off the ground.

In the future to prevent the truck from rolling, chock the rear wheels or set the parking brake.

I had a '94 Olds Bravada with the Borg-Warner AWD T-case, and the it had the G80 in the rear end (best winter driver I've ever had).

Why would they put the G80 on a '94 AWD Bravada, but not a Denali when the G80 is standard on the rest of the Tahoes/Yukons?

 

[6speedblazer]

I had a '94 Olds Bravada with the Borg-Warner AWD T-case, and the it had the G80 in the rear end (best winter driver I've ever had).

Why would they put the G80 on a '94 AWD Bravada, but not a Denali when the G80 is standard on the rest of the Tahoes/Yukons?

Gm uses brake bias to simulate a limited slip differential. Its cheaper amd almost as effective.

Personally im a big fan of ghe viscous coupler style cases used in the bravadas syclone and typhoons silverado ss and early denalis.

 

[TTro33]

Ok so I did some more experimenting and lifted the rear, the brakes work fine, no tight and loose spots like from warped rotors. I ordered a new brake switch since that can affect this whole issue, turned out not to be the right one for an adjustable brake pedal. I took apart the original switch and the bottom contacts were not chromed and corroded, or burnt looking, even the side of the plastic looked a little scorched so I sanded them up. Then I plugged the rear wheel speed sensor I keep unplugged and played around I can turn off and on traction control, remember this is AWD, put it in neutral and put it in 4 lo. Still says service stability. Brakes still doing that thing while going around up and down the driveway, so no progress, unplugged the tire sensor, so the brakes feel good.

I ran across a thread where someone said that in another make of car the rear diff. can have some missing teeth causing the speed sensor on the diff. to cause ABS to come on once per tire revolution, I though Eureka! That is why it doesn't feel like constant ABS on the brakes just intermittent. Pretty sure the Tahoe has no speed senor on the differential, just the bearings, and they can't have missing teeth, or the metal things the speed sensor reads. That leads me to think and shudder, could it be the something in the transfer case, that the transfer case speed sensor is picking up? It would be cool to have everything working but dropping and taking apart the t case would suck. I bought a code reader, maybe that will help.

 

[M1Gunner]

Yes, first step with any diag is to pull current and/or history codes!

 

[kingMautief]

I just put on some new wheel bearings and noticed every time I tried to jack up the front end the Tahoe on a slight rear end decline would move backwards. So after putting some chocks on
the rear tires and finishing, I moved the Tahoe to level ground and jacked up the rear end. The tires spin freely, the drive shaft would make little movements as I spun the tires.

Is my rear diff obliterated, and I been using just front wheel drive for the two years I've had this? ? I was thinking perhaps it engages when in use, and since the traction control, stability control is disengaged because after fixing the wheel sensors trying to solve the error messages and not being able to push to engage the 4 lo button I had to leave one of the rear ones unplugged because when I did fix them, whenever I pushed on the brakes I got this weird push back like the brake petal was moving up and down against my foot, not abs stuttering. I even had the ABS module rebuilt and no fix, but that's a separate mystery, or maybe the cause for the rear wheels spinning freely when jacked..

Anyone familiar with this system? Does traction control and stability need to be working for the rear to get power? Any help would be appreciated, and I do everything possible to avoid a mechanic, so far so good.

Have you found the problem? I have the same issue as of last week.

 

[Fless]

Have you found the problem? I have the same issue as of last week.

The OP hasn't been on here since Jan 2019. Doubt you'll get a response. Recommend starting a new thread for your issue.