Faulty Shift Solenoid Valves
Shift Solenoid Valves harness is open or shorted
Shift Solenoid Valves circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
Hydraulic pressure to each clutch is controlled by the shift valve. The shift valve activates according to the ON/OFF status of shift solenoid valves A, B, C, D, and E. Hydraulic pressure supply in D position is shown above. The line pressure or the clutch pressure control pressure (CPC A, CPC B, or CPC C) is supplied to each clutch by the shift valve activated. The Powertrain Control Module (PCM) computes the actual ratio of mainshaft to countershaft revolutions. If a difference between the actual ratio and the commanded gear occurs when shifting to each gear position, a malfunction in the shift solenoid valve or the hydraulic system is detected and a Diagnostic Trouble Code (DTC) is stored.