Code P028, Transaxle Pressure Switch/Circuit Problem: Notes

WARNING: This page is about a different car, the 1995 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.

PCM checks for illegal transaxle pressure switch inputs (000 & 010) in addition of any of following failure conditions:

Transaxle range switch indicating no in P/N position but transaxle pressure switch input to PCM indicating P/N (101) with a valid drive transaxle gear ratio (3.11 or less).
Transaxle pressure switch input to PCM indicating REV (100) with a gear ratio not within recognized reverse gear ratio range (gear ratio less than or equal to 2.02 or gear ratio greater than or equal to 2.23).
Transaxle pressure switch input to PCM indicating D1 (110), D2 (111), D3 (011) or D4 (001) with a reverse gear ratio (gear ratio between 2.02 and 2.23).

If any of above conditions are met for 5 seconds, Code P028 will set for the entire ignition cycle.