HARNESS AS 2291953 - Caterpillar

Illustration 1 g00518837
(1) Lockup clutch solenoid valve
(2) Modulation reduction valve
(3) Pressure reduction valve For the speed positions that require direct drive, lockup clutch solenoid valve (1) must be activated after the upshift solenoid valve or the downshift solenoid valve is deactivated. The position of the transmission gear switch and the ground speed signal from the transmission speed sensor command the Power Train Electronic Control Module (Power Train ECM) to activate lockup clutch solenoid valve (1) at the correct time.Pump oil from the power train charging pump section sends oil to the power train oil filter. The oil is split after passing through the power train oil filter. Some of the oil goes to the torque converter lockup clutch and solenoid valve. This pump oil goes through pressure reduction valve (3) in the torque converter lockup clutch and solenoid valve. This converts the pump oil to pilot oil. The pilot oil flows to lockup clutch solenoid valve (1) in the torque converter lockup clutch and solenoid valve. When the Power Train ECM energizes lockup clutch solenoid valve (1), the pilot oil will flow to modulation reduction valve (2) in the torque converter lockup clutch and solenoid valve. Modulation reduction valve (2) allows pump oil to flow to the lockup clutch. The lockup clutch will stay in direct drive until the Power Train ECM de-energizes lockup clutch solenoid valve (1).