Five problems related to driveshaft have been reported for the 1999 GMC Sierra. The most recently reported issues are listed below.
The power steering pump driveshaft broke, causing loss of steering & loss of power assisted brakes while towing a 2 horse trailer . On this size vehicle it is extremely difficult to steer or stop even at slow speed. This is the second time this has happened. The first was 09/10/2000, also pulling a two horse trailer. The service manager has told me they have had to replace several of these pumps because of the shaft breaking. The pump assembly # is e9050. If this were to happen at highway speed the results could be catastrophic. There is no indication or warning that this has happened untill you try to steer or stop. In an emergency that may be to late.
Rear end vibrates due to misalignment of drive shaft to axle. Can't figure out why tranmission shifts hard. Tried replacing seat belt to fix tightening on bump.
Would be driving and removing foot from gas pedal for a short while. Would then depress on gas pedal, and it made a loud metallic bang. Would sound like metal against metal. Took to dealer & mechanic lubricated driveshaft. Was working fine until leaving dealership. Have been in to dealer ten times for problem , and it's not resolved.
The rear rotors u-joint, carbon build up on throttle, replaced window motor uses 2 qts of oil every 400 to 500 miles , transmission uses 1 qt of oil every 20000 miles , air conditioner fan does not work on high I believe the throttle build up is a safety issue with the gas petal sticking. We have a lemon.
Throttle body sticks while driving. Had built up dirt and varnish. This caused vehicle to lunge forward when pressing on pedal. Drivetrain makes a clunking noise due to a lack of lubrication. This can cause teeth not to mesh correctly.