Unscrew the locking cap. Do not put the cap "on the head", this can damage the electrical contacts.
Suck the liquid out of the expansion tank using a pipette or syringe.
Dual-circuit (tandem) GTZ: 1 - hydraulic piston rod brake circuit; 2 - "floating" main brake circuit; 3 - primary cuffs; 4 - separating cuffs.
Carefully press the empty expansion tank off the master cylinder with your hands.
When installing, insert new sealing rings into the holes of the master brake cylinder. Pre-lubricate the sealing rings with fresh brake fluid.
Press the expansion tank evenly into the sealing rings. The tank should fit into the grooves. Fill.
Screw on the locking cap. Check the operation of the indicator light switch by pressing on the elastic center of the cap
Bleed the brake system as described.