My automatic transmission will only shift into reverse or first gear.
The computer on these cars are prone to interference if the owner has put on an aftermarket code scanner to the ALDL connector to scan the computer. Some owners use these to monitor system functions or for other reasons. These aftermarket testers have been known to cause many problems with the computer or components in the car like transmission, ABS, Engine and other items that require use of the communication lines that this aftermarket tester also uses. Try to remove the tester and restart the engine and road test for problem to be fixed. I recommend to have a qualified mechanic check it out such as one from YourMechanic.
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