Mitsubishi Hydraulic Pump Problem
This bulletin applies to 2008-2015 Mitsubishi Lancer Evolution and 2009-2015 Ralliart vehicles equipped with AYC/ACD (active yaw control and active center differential, which allows torque transfer between the rear wheels). If the AYC/ACD hydraulic pump bleeding procedure is not followed per the service manual, unusually loud noises will be heard when the pump operates.
A heavy click/clunk noise can be heard after starting the engine and depressing the brake pedal or while the brake pedal is depressed and the engine is then started. The noise is due to air being trapped in the AYC/ACD system. Continue to bleed until the noise is eliminated.
ATF is not filling the area below the filer in the AYC/ACD reservoir. If the bottom 1/3 of the reservoir is not filled with fluid after pouring ATF into the reservoir, squeeze the large inlet hose several times. This will help displace the trapped air and fill the lower 1/3 of the reservoir prior to bleeding the system. If trapped air is not removed, it may be drawn into the hydraulic system during bleeding. (Note: remove the inner trunk panel to view the reservoir).
If you encounter a negative response message from MUT3 SE while attempting to start the bleeding procedure for the AYC/ACD pump, check the steering wheel position. The steering wheel must be at the straight-ahead position for the activation procedure to begin.
After starting the bleeding procedure following service manual directions, keep the reservoir fluid full to prevent air from being drawn into the system.