I njust noticed my steering wheel in my 2000GMC 1500 is now rotated about 100 degrees when the truck is going straight. My mech. says tie rods and tierod ens are tight and everthing seems normal...he did say my idler arm is a little weak but doesn't know how that would affect it...frames not bent and have not been 4 wheelin with it...just one day the steering wheel is turned... weird

You have worn front end parts, most likely tie rod ends. Have it fully inspected.

Because the car need a front-end alignment.
Here's how that works.
The steering wheel is attached to 2 tie rods (they go by different names sometimes).
These tie rods are then attached one to each front wheel.
There are at least 2, and sometimes 4 adjustments for these under the front of the car.
When someone does a front end "alignment". they will loosen all these joints and will set the wheel straight to match the direction of the car.
Over the years, these parts wear and the wheel gets crooked.
Be blessed.

To Remove:

1. Before servicing the vehicle, refer to the precautions at the beginning of this section. NOTE: The wheels of the vehicle must be straight ahead and the steering column in the LOCK position before disconnecting the steering column or intermediate shaft from the steering gear. Failure to do so will cause the SIR coil assembly (clock spring) to become uncentered, which may cause damage to the assembly.
   
2. Lock the steering column by installing the J42640 into the underside of the steering column.
3. Raise and support the vehicle.
4. Remove the tires and wheels.
5. Remove the power steering gear heat shield.
6. Remove or disconnect the following: CAUTION
   Failure to disconnect the intermediate shaft from the rack and pinion stub shaft can result in damage to the steering gear and/or intermediate shaft. This damage can cause loss of steering control, which could result in personal injury.
   
• Intermediate shaft lower pinch bolt and coupling from gear
• Pressure and return pipes from the gear
• Electrical connector, if equipped
  Stabilizer shaft links at lower control arms
• Remove the left stabilizer shaft insulator.
• Rotate the stabilizer shaft to access steering gear bolts.
• The outer tie rod retaining nuts.
• Using J24319-B separate the outer tie rods from the steering knuckles.
• Rack and pinion attaching bolts
• Rack and pinion assembly through the left wheel opening.
7. Transfer the outer tie rods if replacing the power steering gear.

To Install:

1. Install or connect the following:
   • Rack and pinion assembly through the left wheel opening and tighten the bolts to 70 ft. lbs. (95 Nm)
   • Electrical connector, if equipped
     Pressure and return lines to the steering gear and tighten the fittings to 22 ft. lbs. (30 Nm)
   • Heat shield and bolts. Tighten the bolts to 7 ft. Lbs. (10 N)
   • Install the left stabilizer shaft insulator.
2. Install stabilizer shaft Links to lower control arms
3. Intermediate shaft to the steering gear and tighten the pinch bolt to 35 ft. lbs. (47 Nm)
4. Install the outer tie rods to the steering knuckles.
5. Install the outer tie rods retaining nuts. torque the nuts to 22ft.lbs(30 Nm) plus an additional 180 degrees.
6. Install the tires and wheels.
7. Lower the vehicle.
8. Remove the steering column anti rotation pin from the steering column.
9. Fill and bleed the power steering system.
10. Adjust the front toe.

Lock the steering column by installing the Steering Column Anti Rotation Pin tool J 42640 into the underside of the steering column--Aurora


Steering gear mounting bolts--Aurora




Power Rack & Pinion Steering Gear Heat Shield Removal & Installation To Remove:

1. Raise and support the vehicle.
2. Remove or disconnect the following:
   • The stabilizer shaft links.
   • Rotate the stabilizer shaft downward.
   • The electrical harness clip.
   • Power steering gear heat shield mounting bolts.
   • The heat shield.

To Install:

1. Install the power steering gear heat shield.
2. Install or connect the following:
   • The mounting bolts And torque to 89in.lbs.(10 Nm)
   • The electrical harness clip.
   • Rotate the stabilizer shaft into position.
   • The stabilizer shaft links.
3. Lower the vehicle.

Figure of heat shield removed from above rack bolts with location shown

Copied from AutoZone.com:

1. Before servicing the vehicle, refer to the Precautions Section.
2. Turn the steering wheel to the straight ahead position and remove the key from the ignition.
3. Turn the wheel counterclockwise in order to lock the steering column in place.
4. Raise and support the vehicle.
5. Remove the front wheels.
   WARNING Do not rotate the intermediate shaft once separated from the gear. Possible damage or a malfunction could occur.
   
   
   Fig. Steering shaft pinch bolt
   
   
   Fig. Steering gear mounting
   
6. Remove the steering gear to intermediate shaft pinch bolt and discard.
7. Disconnect the intermediate shaft from the steering gear.
8. Remove both steering gear outer tie rod to knuckle nuts and discard the nuts.
   WARNING Do not attempt to separate the joint using a wedge type tool.
   
9. Separate the outer tie rods from the steering knuckles.
10. Remove the steering gear bolts.
11. Remove the rear transaxle mount.
12. Carefully remove the steering gear from the frame and the vehicle through the LH wheel opening.

To install:

1. Install the steering gear to the frame through the LH wheel opening.
2. Install the steering gear bolts. Tighten the bolts to 81 ft. lbs. (110 Nm).
3. Install the rear transaxle mount. Tighten the rear transaxle mount to frame bolts. Tighten the bolts to 44 ft. lbs. (60 Nm).
4. Tighten the rear transaxle mount thru bolt. Tighten the thru bolt to 74 ft. lbs. (100 Nm).
5. Connect the intermediate shaft to the steering gear.
6. Install a new intermediate shaft pinch bolt. Tighten the bolts to 25 ft. lbs. (34 Nm).
7. Install the outer tie rods to the steering knuckles.
8. Install new outer tie rod nuts. Tighten the bolts to 44 ft. lbs. (60 Nm).
9. Install the front wheels.
10. Lower the vehicle.
11. Adjust the toe if necessary.

I changed mine a few months ago. It's pretty straight forward. You will need a jack and a pan to catch your fluid. Make sure you strap the steering wheel to the brake pedal before you disconnect the steering shaft from the rack or you will damage the airbag wire. The airbag is hardwired, not just a contact like the horn and turn signal connections. After you remove the tie rod nuts, you can whack the spindle with a hammer near the tie rods to get them out. Do not hit the tie rod with a hammer. You will need to get an alignment when you are done. It took me about an hour in the driveway.

BRAKE ROTORS WITH HIGH AND LOW SPOTS WILL CAUSE STEERING WHEEL SHAKES ALSO.LOOSE WORN WHEEL BEARINGS - WORN TIE ROD ENDS - WORN LOWER BALL JOINTS.

Chevy is having problems with the steering columns on these models. Feels like a jiggle in the steering wheel when you hit a bump of any kind. Cost about $75 at the dealer for a new part.

turn your steering wheel straight
look at both wheel to see which one is not straight ( may be both )
loose the tie rod end locking nut and turn the rod to whichever way that make the wheel straight.

Genreally speaking the outter tie rod is only worn. The inner connection to the rack is more of a coupling than a rod end. You will need a 22 mm openend wrench and probally a 16mm and a 18mm opened wrench. A set of pliers to remove the old and bend the new cotterpin. Remove wheel cover and loosen the wheel nuts. Jack up the car and place jack stand or wood blocking, (or as a minimum place the wheel you removed) under the car to prevent the car from falling on you while it's in the air. Do not rely on the jack to keep the car up. Cars are heavy. remove wheel Loosen jam nut that locks the tie rod end to the connecting rod of the steering rack, spray adjustment treads with penetetrating oil to help it spin free. You may have to lock the adjustable shaft by the placing wrench on the hex portion of the shaft just inwards of the tread. Remove the cotter pin from the tie rod end. Remove nut. Take hammer and drive the tie rod from the steering knuckle. To help with the alignment of the front wheel try not to move the the steering knucle brake assembly. Unscrew the tie rod , lubricate the tread and in stall the new one. adjust the treads so that the tie rod slides back into the steering knuckle without turning the knuckle. Install the tie rod nut, tighten and secure with new cotterpin. Do not tightnen the jam nut that locks the tie rod nut to the inner adjustment rod for the steering rack, instead place the wheel back on the car, lower car and finish tightnen. with the car lowered, position the car steering wheel straight. Look at right side wheel. You should be able to line the the edges of the front wheel with your eye's with the outside edge of the rear wheel. if this doesn't line up check steering wheel postion. Now after seeing what the wheel alaignment looks like on the right side, go to the left side. If you look along the outside of the left ire and you see the tread of the rear tire , you have to muckh toe out. Lenghten the adjustmne t rod by turning it clockwise. If when you look along the edge of the tire and you don't see the rear tire, turn the rod counter clockwise. Adjust slowly and always check that the steering wheel is in the straight position. Once you have it fairly close to straight, lock the jam nut on the tie rod and take to a wheel alignment company for finishing adjustment. Good luck.

You need to retighten the tie rod end lockdown bolts. The tie rod end srews in and out of the tie rod itself. It's adjustment is secured by a 13mm bolt that clamps the end of the tie rod around the threads on the tie rod end. Tighten that bolt, if the bolt isn't there replace it.