Code 85, Undefined Gear Ratio: Notes

While in each gear, control module calculates actual gear ratio from input and output speed readings, also referred to as vehicle speed, then compares these to what gear ratio should be, taking into consideration selected gear range. This monitor includes reverse gear, but does not include overdrive gear.

1. An out-of-calibration transmission range pressure switch could falsely set Code 85.
2. This test verifies proper ratio.