One problem related to transmission noise has been reported for the 1999 GMC Sonoma. The most recently reported issues are listed below.
Dealer where vehicle was towed for repairs says the automatic transmission must be pulled and disassembled to determine what is broken and the factory will not provide warranty relief since the truck is over 4 years old even though the vehicle has only 36,489 miles. Original warranty was 3 years or 36,000 miles which ever comes first. Vehicle has been serviced by dealer since purchase. The truck gave a high screeching noise and loss of power in the transmission, forward drive gear. I pulled off the fairfax county parkway in herndon and pulled into a parking lot. Next day tried to back up truck and transmission gave screeching noise and vehicle would not move. If vehicle is 2, 3 or 4 years old but only has 36,489 miles why can't GMC provide relief for a vehicle defect in the transmission which is safety related due to loss of power and maneuver ability when it occurred? vehicle is at a GMC dealer which I did not purchase from for repairs as I have had it towed to the nearest dealer for repairs. Can you provide some assistance with GMC on warranty or secret warranty repairs?.