We spend a great deal of time helping installers with electronic-circuit codes for shift solenoids, PC-solenoid codes, input and output speed sensors, and pressure switches. Nearly all vehicles have issues with circuit codes. The focus of this article will be on Chrysler transmissions, as they seem to have more of these types of concerns than other vehicles.
Two- and three-pin harness connectors have been used for quite some time, and they have always been a primary source of circuit problems. The issues with them seem to be getting more prevalent since the vehicles that use them are aging. Loose pin fit and corrosion are the primary causes found with them, and cleaning with a heavy base (baking soda, for example) and a mild steel brush will usually dissolve the corrosion.