Shift Solenoid: Testing and Inspection

Transaxle Mode Switch And Shift Solenoid Circuit Diagram:

Chart C-8B, Transaxle Mode Switch Diagnosis (4 Of 4):

CIRCUIT DESCRIPTION
The PCM controls automatic transmission shift points by the use of solenoids inside the transaxle. The solenoids get power when the ignition is "ON", and become energized when the PCM completes the circuit to ground.

OPERATION

Shift Solenoid Operation/Commanded Gear Selection Chart:

When the transmission is placed in "D" range, the PCM energizes both shift solenoids to engage first gear. The PCM constantly monitors engine speed, vehicle speed and throttle position to determine shift points. When vehicle speed and throttle position sensor signals reach calibrated values, the PCM turns solenoid "A" off, forcing a shift to second gear (second gear - only solenoid "B" is energized). When a third gear shift is required, the "B" solenoid is turned "OFF" (third gear - solenoids "A" and "B" are "OFF"). In fourth gear, only solenoid "A" is energized. The PCM ignores all positions of the "PRNDL" switch except for manual low. When the gear selector is in the manual low position, the PCM will keep both solenoids "A" and "B" energized until the engine reaches 5,400 rpm, when the PCM will turn solenoid "A" off and force a first-second shift. This is to avoid engine and transmission damage.