AWD Shift Selector Problem

[Thauber]

Hey guys, new to this forum but far from new to these trucks. Have had several of them over the years, but just picked up another one the other day. It is a 2004 Yukon XL SLT, and it is their "AWD" version. I bought it knowing it had a few issues, but I really enjoy these trucks and don't mind getting my hands dirty if the price is right. And the dude was great about keeping records of what he had done to it. My '03 of the exact same model and setup was totaled out about a month ago by a USDA employee driving an F150 at 65mph and playing on her damn phone... Had a tear in my eye when the salvage yard guy drove it up on to his flatbed. Was still a damn beast at 180K

Here's the kicker I'm working on now. The truck drives fine, no issues at all, no CEL or warnings (except tire monitor because of aftermarket rims and tires I put on after purchase, so no TPMs in them), but the 4x4 ("AWD") selector will only work in normal AWD or 4 LO (middle and bottom buttons). When I try to select Stabilitrack mode (the top selection on these AWD models), it kicks up a message STABILITY SYS DISABLED, and lights up the TC warning for just a second. It simply refuses to engage that mode. This is a Florida truck, very very little signs of rust anywhere, has had calipers replaced over the last couple years, brake booster and master cylinder, front differential rebuilt about 40k miles ago, but didn't see anything about wheel hubs in his papers. Guessing this mode uses wheel speed sensors, so possible culprit? I checked the hubs for play when I put my tire setup on it, and they were nice and tight, as well as all the steering linkages and ball joints. I asked him about when did it stop going into that mode, but he had no idea because he never changed it from the one it was in.

I read through the discussions that came up using the search, but didn't see anything like this posted. Definitely no REDUCED POWER issue at all, this baby runs like a champ, as well as averaged 18.5 mpg doing 70-72 mph during the 3 hour drive back after buying it. And with 200K on the clock


Looking for advice on where to start. How to diagnose. Not a fan of throwing money at a problem unless I'm pretty damn sure it will do some good.

 

[about20ninj45]

What transfer case do you have?

 

[Doubeleive]

not likely to be wheel hubs if they are tight and no abs light or braking issues

 

[Thauber]

RPO is NR4 - TRANSFER CASE ALL WHEEL DRIVE (AWD), OPEN DIFF, TWO SPEED

I believe that is for the Borg Warner 4482

 

[about20ninj45]

Put it on Jack stands, have someone try to engage stabilatrac mode, while listening for the engagement of the transfer case. If it doesn't sound normal, or doesn't engage, the shift forks in the transfer case could be broken, not allowing it to shift in that mode. I believe their are two shift forks in that transfer case and one could have failed, but it will require disassembly to know for sure.

 

[Thauber]

It makes no attempt to go into Stabilitrack mode. No click or sounds from the transfer case that I could hear. It is in AWD now (FT 4x4 HI), and goes back and forth from there to 4 LO no problems with the proper click and clank.

So does the second fork change the power ratio in the transfer case for Stabilitrack mode? Like from AWD 30/70 to traditional 4x4 at 50/50? Nerding out right about now trying to understand this

 

[swathdiver]

Hey guys, new to this forum but far from new to these trucks. Have had several of them over the years, but just picked up another one the other day. It is a 2004 Yukon XL SLT, and it is their "AWD" version. I bought it knowing it had a few issues, but I really enjoy these trucks and don't mind getting my hands dirty if the price is right. And the dude was great about keeping records of what he had done to it. My '03 of the exact same model and setup was totaled out about a month ago by a USDA employee driving an F150 at 65mph and playing on her damn phone... Had a tear in my eye when the salvage yard guy drove it up on to his flatbed. Was still a damn beast at 180K

Here's the kicker I'm working on now. The truck drives fine, no issues at all, no CEL or warnings (except tire monitor because of aftermarket rims and tires I put on after purchase, so no TPMs in them), but the 4x4 ("AWD") selector will only work in normal AWD or 4 LO (middle and bottom buttons). When I try to select Stabilitrack mode (the top selection on these AWD models), it kicks up a message STABILITY SYS DISABLED, and lights up the TC warning for just a second. It simply refuses to engage that mode. This is a Florida truck, very very little signs of rust anywhere, has had calipers replaced over the last couple years, brake booster and master cylinder, front differential rebuilt about 40k miles ago, but didn't see anything about wheel hubs in his papers. Guessing this mode uses wheel speed sensors, so possible culprit? I checked the hubs for play when I put my tire setup on it, and they were nice and tight, as well as all the steering linkages and ball joints. I asked him about when did it stop going into that mode, but he had no idea because he never changed it from the one it was in.

I read through the discussions that came up using the search, but didn't see anything like this posted. Definitely no REDUCED POWER issue at all, this baby runs like a champ, as well as averaged 18.5 mpg doing 70-72 mph during the 3 hour drive back after buying it. And with 200K on the clock


Looking for advice on where to start. How to diagnose. Not a fan of throwing money at a problem unless I'm pretty damn sure it will do some good.

Welcome Tim, get your bi-directional scan tool and pull the codes. They're not bad enough to set a CEL but they are their because of the warning. Know someone with a Tech-2?

 

[Thauber]

Found some reading material on this BW 8842 transfer case: (also for future readers craving the info)

The Borg Warner (BW) model 4482 NR4 transfer case is a two-speed, full time 4WD, transfer case. The transfer case has an external planetary type differential, which has two different sets of pinion gears. The planetary differential provides a 40/60 torque split front/rear full time. This means the front and rear propeller shafts are constantly being driven for maximum traction in all conditions.

While in the 4HI mode, the transfer case external type planetary differential functions the same as a typical rear axle differential. The transfer case differential pinion gears function as the spider gears, and the sun gears function as the side gears.
The following actions occur because of the planetary differential:
• If the vehicle is on a hoist, and in the 4HI mode, the front propeller shaft can be rotated by hand.
• The vehicle cannot be driven in the 4HI mode if one propeller shaft is removed.
• Operating the vehicle on the hoist, in the 4HI mode, can damage the differential pinion gears, by over-spinning.
• Operating the vehicle with one propeller shaft removed, in the 4HI mode, causes over-spinning of the differential pinion gears.

The BW 4482 design of the planetary differential allows use with the Vehicle Stability Enhancement System (VSES) vehicles. The VSES takes use of the planetary differential, by applying braking to a tire that has less traction and dividing the engine torque to the other axle. A high/low planetary carrier assembly provides the high and low ranges, which is a 4-pinion gear, sun gear, and annulus gear arrangement, giving a 2.64 low range reduction ratio.

The BW 4482 case halves are high-pressure die-cast magnesium. Ball bearings support the input shaft, the front output shaft, and the rear output shaft. A needle roller bearing is located inside of the input shaft gear to support the front of the mainshaft. The rear of the mainshaft is supported by a bronze bearing inside the rear output shaft. The transfer case requires DEXRON®III ATF Fluid GM P/N 12378470 (Canadian P/N 10952622), which is red in color. An oil pump pumps the fluid through the mainshaft oil gallery to the gears and bearings.

Transfer Case Shift Control Switch

The BW 4482 transfer case features a 3-button shift control switch located on the instrument panel. When the vehicle has the ignition key in the RUN position, the transfer case shift control module starts monitoring the transfer case shift control switch to determine if the driver desires a new mode/range position. At a single press of the transfer case shift control switch, the lamp of the new desired position will begin flashing to inform the driver that the transfer case shift control module has received the request for a new mode/range position. The lamp will continue to flash until all shifting criteria have been met and the new mode/range position has been reached, or has been engaged. Once the new mode/range position is fully active, the switch indicator lamp for the new position will remain ON constantly. In addition, the switch includes a VSES request button which sends a voltage signal to the transfer case shift control module. The transfer case shift control module in turn sends a request via the class 2 data bus to the ABS control module which controls the VSES system.

During normal driving situations, the transfer case operates in the 4HI mode. When the 4HI mode is selected, the transfer case shift control module sends 12 volts to an electrical motor, which is the transfer case encoder motor. This motor rotates the transfer case shift detent lever shaft which moves the shift forks and range sleeve to obtain different modes/ranges.

The BW 4482 transfer case has the added feature of also providing the driver with 2 selectable mode/range positions and a VSES request button:
• 4HI - Full Time 4 Wheel Drive
• 4LO - 4 Wheel Drive Low Locked
• VSES - Vehicle Stability Enhancement System

The transfer case will not allow a shift into or out of 4LO unless the following criteria has been met:
• The engine is running.
• The automatic transmission is in Neutral.
• The vehicle speed is below 5 km/h (3 mph).

This transfer case also has a Neutral position. A shift to the Neutral position allows the vehicle to be towed without the transmission output shaft rotating. Refer to the Owners Manual for instructions for proper towing of the vehicle.

Neutral position may be obtained only if the following criteria have been met:
• The ignition switch is ON.
• The automatic transmission is in Neutral.
• The vehicle speed is below 5 km/h (3 mph).
• The transfer case is in the 4HI mode.

Once these conditions have been met, press and hold both the VSES and 4LO Lock buttons for 10 seconds. When the system completes the shift to neutral, the red neutral indicator will illuminate.

4HI Mode Power Flow

When the BW 4482 is in 4HI mode, the engine power flows from the transmission to the input shaft (1). The input shaft (1) is connected to the mainshaft (3) by the high/low range sleeve (2). The high/low range sleeve (2) outer teeth are engaged with the input shaft (1) high-speed teeth. The range collar is slip splined to the mainshaft (3). The mainshaft (3) delivers the power flow to the planetary differential (6), which splits the torque 40 percent through the front differential pinion gears (5) to the front sun gear (10). The torque to the front axle then goes through the drive sprocket (4), via the chain (11) to the front output shaft (12) and to the front axle. The differential planetary splits the torque 60 percent to differential rear pinion gears (9) and rear sun gear (7). The rear sun gear is connected to the rear output shaft (8) and the torque flows to the rear axle.

4LO Lock Mode Power Flow

When shifting the transfer case to the 4LO Lock mode, it commands the encoder motor (12) to turn the shift detent lever shaft (13), to rotate the shift detent lever cam (16). There are two cam profiles on the shift detent lever cam (16) functioning at the same time. The range profile on the shift detent lever cam (16) moves the high/range shift fork (18) and the high/low range sleeve (4) rearward to the 4LO range position.

The mode profile on the shift detent lever cam (16) moves the mode shift fork (17) rearward along with the mode shift collar (6).

The high/low range sleeve (4) outer teeth disengage from the input shaft (1) high-speed teeth. The high/low range sleeve (4) outer teeth then engage in the high/low planetary carrier teeth (19). The power flow is now from planetary teeth on the input shaft (1) to the planetary gears (2) in the carrier. Rotating the planetary gears, which are engaged in the annulus gear (3), rotates the planetary carrier. The planetary carrier delivers the power to the high/low range sleeve (4). The high/low range sleeve (4) then drives the mainshaft (5), providing a 2.64:1 reduction to the speed of the mainshaft (5).

The mode shift collar (6) locks the mainshaft (5) to the drive sprocket (7). Torque is sent by the chain (14) to the front output shaft (15) and to the front axle.

The rear propeller shaft power flow is delivered by the case of the planetary carrier (8) being splined to the mainshaft (5). The power flows from the planetary carrier case to the rear pinion gears (11), to the rear sun gear (9), and to the rear output shaft (10).

The torque distribution in this mode is now determined by vehicle dynamic conditions and weight distribution. The planetary differential (8) is not operating, and both the front and rear propeller shafts are being driven at equal RPMs, therefore giving a 4 low lock mode. This mode should only be used for extra traction during off road use. Using this mode on dry pavement will cause tire scuffing.

Neutral Mode Power Flow

Shifting to the neutral position, the high/low range sleeve is centered between the input shaft and the high/low planetary carrier. The high/low range sleeve is not engaged with either the input shaft or the high/low planetary carrier teeth. The planetary differential is in the 4HI mode.

Transfer Case Electrical Components

View the list of major electrical components that make up the full time four wheel drive transfer case (FT4WD) system below.

Service 4WD Indicator

The SERVICE 4WD indicator is an integral part of the cluster and cannot be serviced separately. This indicator is used to inform the driver of the vehicle of malfunctions within the FT4WD transfer case system. The SERVICE 4WD indicator is controlled by the transfer case shift control module via a Class 2 message.


Wish I could find the pics that go with this info.

 

[Thauber]

Know someone with a Tech-2?

I sure don't, just have a normal scan tool. It may be time to get one soon. Is there a certain brand you recommend?


EDIT:

Sorry, should have been more specific. If I do decide to get a diagnostics tool, do you recommend the GM Tech2? Or one of the tools from Autel, or Bosch, or Snap-On?

 

[about20ninj45]

It makes no attempt to go into Stabilitrack mode. No click or sounds from the transfer case that I could hear. It is in AWD now (FT 4x4 HI), and goes back and forth from there to 4 LO no problems with the proper click and clank.

So does the second fork change the power ratio in the transfer case for Stabilitrack mode? Like from AWD 30/70 to traditional 4x4 at 50/50? Nerding out right about now trying to understand this

There's only two shift forks, one for high and one for low. If your engaged in one more and not the other, then yes, a shift forks could have failed, only way to know for certain is to drop that transfer case and crack it open. Also, you won't get a coffee for broken pads on a shift fork

 

[about20ninj45]

It makes no attempt to go into Stabilitrack mode. No click or sounds from the transfer case that I could hear. It is in AWD now (FT 4x4 HI), and goes back and forth from there to 4 LO no problems with the proper click and clank.

So does the second fork change the power ratio in the transfer case for Stabilitrack mode? Like from AWD 30/70 to traditional 4x4 at 50/50? Nerding out right about now trying to understand this

There's only two shift forks, one for high and one for low. If your engaged in one more and not the other, then yes, a shift forks could have failed, only way to know for certain is to drop that transfer case and crack it open. Also, you won't get a coffee for broken pads on a shift fork

 

[Thauber]

There's only two shift forks, one for high and one for low. If your engaged in one more and not the other, then yes, a shift forks could have failed, only way to know for certain is to drop that transfer case and crack it open. Also, you won't get a coffee for broken pads on a shift fork

Okay, so if I'm understanding the functions, then no Stabilitrack would not likely have anything to do with mechanical internals on the t case? Hi and Lo have no problems whatsoever.

I wish I still had access to my '03 that was the same setup. Everything on it worked, and I don't recall hearing anything from the t case when selecting Stabilitrack mode, but maybe I just wasn't listening hard enough. I assumed it was all electronic, simply using wheel speed and abs sensors to apply brakes as the way to transfer power to the correct wheel(s). Anyone have one of these "AWD" setups and can verify if there is any sound from t case when changing from the normal mode (center button) to Stabilitrack mode (top button)?

Still hunting for a neighbor with a Tech 2 or similar.

 

[afpj]

I'm a simpleton so please don't flame me for these simple suggestions;
Check fuses? Since I don't have stabilitrack don't know if there's a fuse for that or perhaps abs as well. Since that system uses abs for proper function a mid grade scanner should see abs pending codes, live data on the wheel speed sensors to see if one or more is wonky. Just throwing some hopefully cheaper ideas out.

 

[Thauber]

I'm a simpleton so please don't flame me for these simple suggestions;
Check fuses?

All good man, sometimes we forget those simple things and cause ourselves some major headaches. I didn't check for that fuse specifically, but I have been over the two fuse panels and checked that every fuse was working. Being the truck had issues when I went to buy it, I went over everything I could to make sure I was okay.

I had a friend call me once, he was running late for a business meeting and his 2014 F150 with about 100k on the clock wouldn't start. Dash lights all came on, but no attempt to engage starter. Being a good friend, I had convinced him several months before when helping with a project that he needed to get a simple multi-meter to have around. I must have walked him through about 20 minutes of things to look at, check voltages, test fuses, etc, before it hit me like a brick. I asked "Dude, do you have a spare key?".... Truck started right up. Sometimes it is the simplest of things.

Anyway, back to this Yukon, I have someone coming over on the morrow with a Tech 2!! Hoping to find some answers.

I have also been repairing the A/C system on this. He had a quote a local shop gave him to fix the hot air coming out the passenger vents and rear vents when A/C was supposed to be on, they wanted $1k to fix it, with $600 of that for labor to remove/install dash for that passenger blend door actuator. I got home and said screw that, its summer, popped the dash vent out, "helped" the actuator get the passenger blend door to the cold side, then unplugged it. It's a damn tight fit to reach that bastard though. Rear was a breeze to move to cold and lock. Have new ones on the way, I'll get them in before it gets too cold.

 

[TM98]

I don’t recall hearing a noise when I hit the top button. I’m thinking it’s more electronic as it disables the stability and traction control. I will have to check later when I get a chance.

 

[Thauber]

I don’t recall hearing a noise when I hit the top button. I’m thinking it’s more electronic as it disables the stability and traction control. I will have to check later when I get a chance.

Thanks, much appreciated.

The guy with the GM Tech 2 wasn't able to come by yesterday after all, will be next weekend.

 

[TM98]

I pushed the stabilitrack button last night and the only thing it did was a single chime, said stability sys disabled, and had the t/c light up in the dash. They both stayed on until I hit the button again to turn it back on.

 

[TM98]

I also found this searching about the stabilitrack system. I do know if the system senses wheel slip it will cut power to the engine and you cannot give it more gas. I found that out the hard way the first time I drove out on the beach in very soft sand. Now anytime I drive on the beach I disable the stabilitrack system.

The StabiliTrak Vehicle Stability Enhancement System improves vehicle stability, particularly on slick surfaces or during emergency maneuvers. The system uses an array of sensors coupled with a master electronic control module to constantly monitor the driver’s steering commands. When StabiliTrak senses one or more of the wheels slipping, loss of lateral traction (side slip), understeer (plowing) or oversteer (fishtailing), the system adjusts engine torque and/or brake pressure at individual wheels to help the driver get the vehicle back on track.

 

[Thauber]

Thanks for that. I'm assuming your vehicle setup is also the 2-speed AWD version, with the 3 button selector where normally the 4 button 4x4 (or 3 if no Auto 4x4) switch is?

One like this:

For those that don't have one or haven't seen one, they really aren't that uncommon. This is the second one I've owned. Manual shows middle button as normal AWD (equates to FT 4x4 HI with power split 60/40) and the bottom is obviously 4LO. There is no 2wd on this vehicle, thus why they called this AWD, just with 2 speeds.

I can shift between them no problem whatsoever. It is when I try to activate the Stabilitrack (top button) that is says "nope, not gonna happen". I get the same message yours (TM98) shows, but only for a second or two and they go away, with the light never changing from normal AWD (middle button) to Stabilitrack (top button). My simple OBDII scan tool shows no codes, so if this guy doesn't show with a Tech 2 this coming weekend, I'll have to shell out $100 for the local stealership to tell me if there is a code hidden in there. Would be $75 cheaper to buy a used switch and swap them, but I hate buying parts that I don't know that I need... yet...

 

[afpj]

Hold on a minute... your saying that when you hit the top button, the stabilitrack system is disabled. Isn’t that what’s suppose to happen? When you start the car, I thought the stabilitrack system is automatically engaged. So when you hit the top button for the first time after a start, it will disengage. I’m missing something.

 

[Thauber]

Yes and no. It should behave the way TM98's does, with with message of "stability system disabled" on DIC and TC OFF light staying on. Mine just flashes up for about 2 seconds and disappears, as in both the message and the TC OFF light. It does not remain OFF like it is supposed to.

I think the miscommunication is I'm not trying to turn Stabiltrack ON, it is ON, but when I activate that button (depress it), it should shut Stabilitrack and TC OFF and stay OFF until I turn it back ON, or turn the vehicle off and then restart it. My apologies if I causes confusion on that part. By activate the button, I'm simply meaning "push the button to make it do what it is supposed to do", and this one isn't doing that, AKA turning OFF Stabilitrack and TC and keeping them OFF. I may have also confused when saying light for the top button, there is no light. Again, my apologies for not being clear.


What I was looking for is someone else that has had this issue or seen this issue and knows what to probe with a multi-meter to track the cause of it. Being there are no codes coming back on the scan tool, I fear there is a separate computer module that is to blame. If my neighbor ever makes it over with his Tech 2, perhaps that can see what the cause is, but that is also assuming he would know how to find it through that tool.



Edit: TM98's, not TD98's, oops