VERSA TRAC (AWD) probs

[STATIC_X]

I have a AWD disable light on and was wondering what it could possibly be. I noticed in the owners manual that in order to change the lube in the rear drive unit and the transfer case it needs chevy`s versatrac lube. Is there any substitute for that, like 75w90 or some other synthetic lube.
Also was wondering if there is a common problem with that versatrac system that I need to check out. PLEASE help me I am getting tired of having that HUGE light on the dash reminding me that I coulod have a huge repair bill in my future.

[rdh2]

Unfortunately, there is no alternative to the Versatrac lube from the dealer. The capacity is 2.1 quarts and at $25 for a 16 oz. bottle, you're going to spend $100+. (And GM wonders why they are in trouble)

From the factory manual:

In the event a spare wheel of a smaller diameter is used on any of the four positions, the wheel rotational speed difference is detected by the wheel speed sensors of the anti-lock brake system (ABS) system. The powertrain control module (PCM) directs the clutch pump check valve to close and block oil flow to the gerotor pumps. The clutch pump check valve also monitors the sump oil for an over-temperature condition. If differential oil temperature exceeds 110°C (230°F), the valve will close and block oil flow to the gerotor pumps. In both spare wheel usage and over-temperature conditions, a "closed" valve will alert the PCM to illuminate the control panel "AWD Disable" light.

From personal experience, a difference in tread depth on the tires can also trigger the light. All 4 tires had equal tread and were about half worn. I had to replace 1 rear with a new tire and that triggered the light. By replacing the other rear tire so the treads matched, the light extinguished.

I have spoken to another person who had a wheel bearing "growl". The "growl" appeared to have caused interference with the ABS signal and triggered the Disable light.

From the factory diagnostics:

Factors that may contribute to an inoperative rear differential include:

• Low gear oil levels

• Differential inoperative due to antilock brake system (ABS) function

• Inoperative powertrain control module (PCM) and/or wiring system

• A mini spare or different size tire installed

• A fluid over-temperature condition

• An inoperative or "stuck" clutch pump check valve

• A defective rear differential assembly

• An inoperative transfer case assembly

A dealer or independent shop with the appropriate scan tool can retrieve codes related to the Disable light. It may be worthwhile to have those codes read to have a good starting point.

[STATIC_X]

Well now my next question would be now, can I remove the drive shaft to the rear drive unit, I noticed that it does not utilize a Ujoint knuckle system more likely a CV joint system instead. What is involved in removing it from vehicle. I did see that there were around 6 to 8 bolts securing the shaft to the transfer case and the same at the carrier bearing assembly. If I do remove the shaft is there going to have, have a plate or something like that installed to keep the other half of the knuckle assembly clean and dry?

[rdh2]

From the Service Manual:

The propeller shaft (3) is of a tubular design with constant velocity joints at both the transfer case and the torque tube flanges. The forward and rearward ends of the propeller shaft mate to the transfer case and the torque tube flanges with 6 bolts each (2, 4) utilizing special crescent-shaped washers to pair the bolts together in order to evenly distribute the clamping force.

The front constant velocity (CV) joint receives the rotational forces from the transfer case output flange. The front CV joint is of a ball-and-groove design using 6 ball bearings set in a race. The CV joint allows axial, but not lateral movement of the joint in order to compensate for the driveline inclination changes imposed by the powertrain during acceleration and deceleration. The CV joint is lubricated with a special grease that is protected from foreign material contamination by a seal similar in design to the seal on a front wheel drive shaft. The mating surface of the CV joint is protected by a metal cap which is crimped on to the CV joint, and captured between the CV joint and the transfer case output flange.

The rear CV joint receives the rotational forces transmitted through the propeller shaft from the front CV joint. These forces are then transferred to the torque tube input flange. The rear CV joint is similar in design to the front CV joint, although the rear CV joint allows lateral as well as axial movement. The lateral and axial movement of the CV joint compensates for driveline inclination changes as well as the lateral movement of the driveline during acceleration and deceleration. The CV joint is lubricated with a special grease that is protected from foreign material contamination by a bellows-type seal. The mating surface of the CV joint is protected by a metal cap which is crimped on to the CV joint, and captured between the CV joint and the torque tube input flange.

The propeller shaft and the constant velocity joints are not serviceable. The CV joints and seals should be inspected periodically, whenever the vehicle is raised for service.

Also,

The Versatrak® on-demand system operates as follows: The propeller shaft assembly, mated to the output flange of the transfer case, is constantly rotating and spins at a rate equal to an average of the two front wheels. Under normal straight-ahead non-slip driving conditions, the external (2) and internal (10) gears of the differential gerotor pumps are rotating at an equal rate of speed. Under those conditions, there is no speed differential between the pump gears, no pump pressure created, no clutch pack activation, and no torque transfer. During a front-wheel slip condition, the external gears (2) of the gerotor pumps rotate at a faster rate of speed than the rear-wheel driven internal gears (10). The gerotor pumps pull oil from the sump through the clutch pump check valve sending pressurized oil to each individual piston to activate the separate clutch packs. On-demand torque/drive is provided to each of the rear wheels as required. A valve internal to each piston housing controls maximum clutch pack pressure. A second valve within each housing is temperature compensating and controls fluid flow based on ambient temperature. The system operates in both forward and rearward vehicle directions.

In the event a spare wheel of a smaller diameter is used on any of the four positions, the wheel rotational speed difference is detected by the wheel speed sensors of the anti-lock brake system (ABS) system. The powertrain control module (PCM) directs the clutch pump check valve to close and block oil flow to the gerotor pumps. The clutch pump check valve also monitors the sump oil for an over-temperature condition. If differential oil temperature exceeds 110°C (230°F), the valve will close and block oil flow to the gerotor pumps. In both spare wheel usage and over-temperature conditions, a "closed" valve will alert the PCM to illuminate the control panel "AWD Disable" light.

From the descriptions, I don't know what effect removing the propeller shaft would have on operation of the van. I suspect there may be an adverse effect. I would try to have a system diagnostic run; it may be an inexpensive fix. Good Luck!

[shampooguy]

I think I read somewhere in the Silhouette forum that someone used Amsoil dif lube in their rear axle. Alot cheaper alternative, and maybe a bit better.

[Monty66]

My ABS light and AWD disable light came on in my '02 Venture last winter. I knew I had a noisy rear wheel bearing. I had one of the big chain auto parts places look for codes in the computer, but it just showed a traction control fault or something and did not identify which wheel was causing it. I replaced both wheel bearings and it fixed it. One of the bearings was so bad I couldn't turn it by hand after I removed it! It no doubt damaged the internal wheel speed sensor when it went bad.

Anyway, same problem again a few weeks ago, so I decided to replace front wheel bearings. Removed them both and they both felt brand new. Replaced them anyway and the ABS and AWD is fine again.

Before changing the front wheel bearings I would drive a few blocks and everything was fine until you hit a bump or made a right turn and then the light would come on. It would stay on until you turned the van off. Evidently it had a bum sensor coil.

I ohmed out the old one compared to the new one and they checked the same, but maybe with some heat or vibration a connection broke down.

Hope this helps.

tom