Transmission Shifts Frequently Between 3RD & Overdrive When Driving Uphill (4-Speed A/T)

If transmission is shifting frequently between 3rd and overdrive when driving uphill on vehicles equipped with 4-speed A/T, perform the following procedures in order:

• Perform THROTTLE VALVE OPENING SIGNAL CIRCUIT CHECK  under SYSTEM TESTS.
• Perform OVERDRIVE & TCC OFF COMMAND SIGNAL CIRCUIT CHECK (A/T)  under SYSTEM TESTS.
• Replace actuator with known-good unit. See ACTUATOR ASSEMBLY  under REMOVAL & INSTALLATION.