AWD disable and anti-lock light is on after changing a rear coil-spring. I had to disconnect the speed sensor from the wheel hub assy (I did reconnect). Any ideas on fix? It was sugested to repalce the hub assembly as i probably damaged the sensor.

You need to have the ABS system scanned. You probably have a bad wheel speed sensor. most likely located in one of the hub bearings meaning; you may have to replace a hub wheel bearing assy with the faulty sensor. Traction control uses the same speed sensors as ABS. when the warning lights are on the system is not working.

Hi! Matt, Most likely if the anti-lock brake light and the awd disable light come on at the same time a wheel bearing / wheel speed sensor assembly is faulty.Listen for a humming noise when driving and try to determine where it is coming from(left/right/front/ back) or any looseness/play in any wheel. That's the possible bearing/wheel speed sensor causing the problem. Or have the abs system scanned to determine which wheel sensor is reading incorrectly.If the awd disable light is off then the awd system should be funtioning.

It's called a wheel speed sensor..what do you want to know? Some vehicles have replaceable sensors and some you have to change the wheel bearing hub assy on the front's and rears, what is the code it is throwing ? a scanner should be able to pull code and also read each speed sensor individually to pin-point which is bad

Adjustment

1. Place parking brake lever in -full released- position.
2. Raise and support vehicle.
3. Remove plug in parking brake shoe support to access adjuster star-wheel.
4. Through the access hole, rotate the adjuster star wheel in the following direction to expand the shoes outward against the drum:
   1. Left brake - Rotate star-wheel toward rear of vehicle.
   2. Right brake - Rotate star-wheel toward front of vehicle.
5. Using an appropriate tool, turn adjuster star wheel until wheel will not rotate (dead lock).
6. Back off adjuster six detents (teeth).
7. Rotate wheel, checking for light drag. If drag is too heavy, continue to back off adjuster one detent at a time until light drag is present. Do not back off star-wheel more than 17 detents from wheel lock.
8. Install access plug.
9. Adjust opposite wheel parking brake shoes using same method.
10. Lower vehicle.
11. Apply and release parking brake lever once to ensure proper operation of parking brakes.

Removal & Installation NOTE The following procedure may be used to remove shoes on either side of the vehicle.

1. Lock out automatic adjuster in parking brake lever.
2. Raise and support vehicle.
3. Access and remove rear hub and bearing.
4. Remove parking brake cable bolt at knuckle.
5. Completely back off parking brake shoe adjustment.
6. Remove parking brake shoe adjuster spring.
7. Remove shoe adjuster.
8. Remove upper brake shoe hold-down clip and pin.
9. Remove lower brake shoe hold-down clip and pin.
10. Remove upper and lower shoes with return spring from shoe actuator.
11. Remove return spring from shoes.
    
    

    Fig. View of the actuator (1), support (2), adjuster spring (3), return spring (4), caliper adapter (5), shoes (6), hold-down clips and pins (7) and adjuster (8)
    

To install:

1. Install return spring between upper and lower shoes.
   NOTE Before installing shoes on actuator, make sure actuator hooked to rear cable is positioned with word -UP- facing outward.
2. Install upper and lower shoes with return spring on shoe actuator located on parking brake cable.
3. Install lower brake shoe hold-down pin through rear of support and lower shoe, then install hold-down clip.
4. Install upper brake shoe hold-down pin through rear of support and upper shoe, then install hold-down clip.
5. Install shoe adjuster. Place end of adjuster with star wheel upward.
6. Install parking brake shoe adjuster spring.
7. Install bolt securing parking brake cable to knuckle and tighten bolt to 21 ft. lbs. (28 Nm).
8. Using Brake Shoe Gauge, Special Tool C-3919, or equivalent, measure inside diameter of parking brake drum portion of rotor.
9. Place Gauge over parking brake shoes at widest point.
10. Using adjuster star wheel, adjust parking brake shoes until linings on both park brake shoes just touch jaws on gauge. This will give a good preliminary adjustment of parking brake shoes, before a final adjustment is made at end of this procedure.
11. Install hub and bearing with wheel speed sensor as well as all components necessary to access it.
12. Lower vehicle.
13. Unlock automatic adjuster in parking brake lever.
14. Perform final adjustment of parking brake shoes

15. 
    Adjustment This vehicle is equipped with permanently sealed rear wheel bearings. There is no periodic lubrication or maintenance recommended for these units.
    

    
    Removal & Installation

    1. Raise and support vehicle.
    2. Remove wheel mounting nuts, then tire and wheel assembly.
    3. If equipped with AWD:
       1. Remove cotter pin, nut lock and spring washer from half shaft.
       2. While a helper applies brakes to keep hub from turning, remove hub nut and washer.
    4. Remove brake caliper and rotor from hub and bearing assembly.
       
       

       Fig. Hub assembly
       

    5. Disconnect vehicle wiring harness connector at wheel speed sensor connector.
    6. Unclip wheel speed sensor connector from spare tire mounting support.
    7. Disconnect two sensor cable routing clips on rear suspension crossmember.
    8. Disconnect two sensor cable routing clips along toe link.
    9. Disconnect sensor cable from bracket on brake support.
       
       
    10. Completely loosen, but do not remove four bolts fastening hub and bearing in place. Once loosened from threads in hub and bearing, push bolts up against rear of hub and bearing to keep brake support plate in place when hub and bearing is removed.
        
        

        Fig. Rear hub and bearing mounting bolts
        

    11. Pull hub and bearing off knuckle and half shaft (if equipped with AWD), then thread wheel speed sensor cable through hole in brake support plate as it is removed with hub and bearing.
        
        
    To install:
    
    1. Position hub and bearing bolts though rear of knuckle and parking brake support just enough to hold support in place as hub and bearing is installed.
    2. Install hub and bearing by first feeding end of wheel speed sensor cable through hole in bottom of parking brake support. As this is being done, if equipped with AWD, slide hub and bearing onto half shaft. Place hub and bearing through brake support, onto knuckle, lining up mounting bolt holes with bolts and placing wheel speed sensor head at bottom.
    3. Install four bolts fastening hub and bearing in place. Tighten mounting bolts to 60 ft. lbs. (81 Nm).
    4. Place wheel speed sensor cable routing grommet into bracket on parking brake support.
    5. Route wheel speed sensor cable along toe link and rear suspension crossmember connecting routing clips where shown.
    1. Connect vehicle wiring harness to wheel speed sensor connector.
    2. Install brake rotor and caliper.
    3. If equipped with AWD:
       1. Install washer and hub nut on end of half shaft.
       2. While a helper applies brakes to keep hub from turning, tighten hub nut to 180 ft. lbs. (244 Nm).
       3. Install spring washer, nut lock and cotter pin on end of half shaft.
    4. Install tire and wheel assembly. Install and tighten wheel mounting nuts to 100 ft. lbs. (135 Nm).
    
    
    

    
    
    

On my 2006 Montana AWD I had this same problem. It also disabled the auto start. There are 4 sensors, one on each wheel hub so either you can hear what sounds like a bad bearing while driving and locate it that way or you can have it hooked up to a diagnostic computar which should also tell you which one is bad. On the 06' the sensor and wheel hub are sold as one piece. Since owning this vehicle I have had to replace three hub assembles which do actually fix the problem till the next one fails. I have found this to be a common problem.

Yes on both questions, I have gotten bad ones right out of the box

awd disable is usually a $200 tube type sensor in the rear diff. abs light is usually front hub bearing

Rear wheel hub(s) will cause the AWD light to come on and sometimes off. After awhile that light will just stay on until you get the rear wheel hub replaced. You can either have a dealer do it for approx $500.00 or you can get the part at AutoZone for $129.00 and do it yourself. This will turn off the AWD light and also quiet the rear noise you hear.

AWD disabled from a sensor unit in rear differential that senses high temp. This thing is over $300. Whine is from fluid. Need to change fluid. This versatrack fluid is about $40 per bottle and you need 3 bottles. Thumping noise is from loose rear knuckle bushings. These are part of the entire rear knuckle assy. and you must replace complete knuckle.

I own the 2002 Buick Rendezvous CX and I've encountered the same problems listed here. The ABS / Traction Control Lamp stays on and was throwing a code for the left wheel speed sensor as well as an anti-lock brake code (both in the wheel bearing hub assembly). I replaced the left and right front wheel hub assembly yet this did not eliminate the abs codes. 
Ultimately, I traced this problem to a break in the wire that leads to the left hub assembly. Although the sensor was properly connected, the wire (which is encased in a plastic housing) was broken. This is the wiring which leads from the abs wiring harness under the hood down to the left wheel abs sensor. 
I would suggest that you simply remove the left wheel and inspect the wire that leads to the abs sensor (there is only one wire on each wheel). Mine literally fell apart when I removed the plastic housing around the wire. I spliced the wire together and put it back in the plastic housing. After this, my abs codes disappeared and my anti-lock brakes began working again!
This is a simple fix that many people spend $1000 + on by replacing the hub assembly which does not fix the problem.