Calculated Ratio

Undefined Ratio Circuit:

Ratio is an input calculated by the PCM/TCM from the output and input speed sensor readings.

If the PCM/TCM calculates a ratio for gears 1st, 2nd and 3rd, that is inconsistent with the gear being commanded by the PCM/TCM, and the condition lasts for over 2 seconds, Code 85 (undefined ratio) will set.

While code 85 is present, line pressure (force motor duty cycle) will be set to a default value. If the undefined ratio condition goes away, normal transmission operation will resume after the next ignition cycle.