A/T Won't Kick Down Out of Overdrive - Faulty TPS

Transmissionbeginner✓ OP Confirmed

Problem

Automatic transmission would not kick down out of overdrive when accelerating. The car would just slowly accelerate instead of downshifting. Problem appeared after winter storage despite the car running and driving fine before.

Transmission won't kick down out of overdrive when stepping on the gasCar slowly accelerates in OD instead of downshiftingWith OD on, RPMs rise then drop ~500 RPM before rising againOccasional RPM bouncing when coasting to a stop before settling to idleDrives mostly normally with OD turned off, but still not quite right

Root Cause

Faulty Throttle Position Sensor (TPS). The TPS provides throttle angle data to the transmission control module, which uses it to determine when to command downshifts. A failed or out-of-spec TPS prevents the TCM from recognizing wide-open throttle and commanding a kickdown.

Confidence

High confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted March 2021 on SupraForums.com