Automatic transmission hesitant or won 't upshift

SOURCE: 2005 Toyota Corolla with 36,000 miles Transmission now "jumps" into gears

hi,
when the check engine light comes on, your car goes into a mode where instead of everything being normal, things are forced, to try and compensate for something else being wrong. It most likely does need a new timing belt, and a complete tuneup INCLUDING plugs and wires. we have a 1984 toyota corolla and it purrs like ground rice, I suggest the tuneup to continue proper rice production.

J

SOURCE: Transmission "jumps" in all gears

Check the idle speed.

SOURCE: 1992 toyota 4 runner 4wd v6

There is an electronic module called ECT under the dash that controls the transmission ( a small computer), however if you had your vehicle serviced in the recent past the wiring connector (a 3 Pin connector) under the Drivers side (LHD) just before the T/case could have become loose or the wires broken, check this connector out.

SOURCE: automatic transmission won't upshift

has something stuck between the linkage visually inspect it as well as check the gear oil level hmmm check the vacuum line going to it ..ensure it is connected and not dry-rotted causing a leak

SOURCE: automatic transmission, gear shift stck in park,

There is a solenoid that controls this. The brake pedal energizes the solenoid. You can bypass this by popping the little clip down by the shifter and sticking a key into the slot to get it to a garage for repair.