Solenoid Application Charts

The solenoid application chart below is a tool used to diagnose automatic transmission shift problems. Transmission solenoids are electrohydraulic actuators that the TCM uses to control the flow of pressurized transmission fluid throughout the transmission.

Transmssion solenoid chart showing the symptoms of a bad shift solenoid A.

A quick glance at the chart reveals that activating shift solenoid A causes the transmission to shift into first and forth gears. The TCM powers solenoid B to shift into first and second.

It contains two shift valves, A and B, that provide for four different shift valve combinations; a four speed transmission. The TCM powers both solenoids for first, solenoid B for second, neither for third, and solenoid A for forth.

Clutch and band application chart.

Using solenoid and clutch and band charts a technician can quickly interpret which solenoids and which friction devices are activated for each gear. Through a process of elimination it can be determined if it’s electrical or mechanical in nature.