CAUTION: When replacing any component upstream of the Hydraulic Control Unit (HCU), including the HCU itself, the brake system MUST be bled using the appropriate T4 procedure to ensure that all air is removed from the new part(s).
NOTE: The brake system can be bled using the appropriate T4 procedures or using the procedure below. The procedure below is for bleeding the brake system when replacing components after the HCU.
NOTE: If the operations performed affected only one of the brake system circuits - main or auxiliary - then only this circuit is bled. Partial bleeding of the brake system is permitted only in the case of minimal losses of brake fluid when disconnecting the brake pipe or hose.
1. CAUTION: Never work on a vehicle supported solely by a jack. Always support the vehicle securely.
Raise and support the vehicle.
2. Make sure all brake system connections are tight and there are no signs of leaks. If there are signs of brake fluid leaks, find the cause of the leak and fix it before bleeding the brake system.
3. Press and release the brake pedal until the vacuum booster disengages.
4. Remove the manifold panel. Release the 2 clamps.
5.
CAUTION: Do not allow dirt or foreign fluids to enter the reservoir. Use only fresh brake fluid from a sealed container that meets technical requirements. Do not mix different grades of brake fluid because of possible incompatibility.
CAUTION: Brake fluid may damage paintwork if it comes into contact with it. If coolant is spilled, remove it immediately and rinse the area with water.
Remove the brake fluid reservoir cap. Disconnect the brake fluid reservoir electrical connector.
6. Add brake fluid to the reservoir up to the MAX mark.
7. Attach the bleeder tube to the brake caliper bleeder nipple and submerge the end of the bleeder tube in a suitable container containing a small amount of the specified brake fluid.
8. Start with the brake caliper farthest from the master cylinder: loosen the bleed screw about a half to three-quarters of a turn.
9.
CAUTION: Throughout the bleeding procedure, the brake fluid reservoir must remain filled with new, clean brake fluid.
With the help of an assistant, press the brake pedal evenly all the way down and allow it to return to its original position. Repeat the procedure until clean, bubble-free brake fluid begins to flow into the container.
10. When clean, bubble-free brake fluid starts to flow into the container, press the pedal and do not release it.
11.
CAUTION: After bleeding, do not forget to put the cap on the bleed nipple. This will protect the bleed nipple from corrosion.
With the brake pedal fully depressed, tighten the bleed screw. (tightening torque 10 Nm).
12. Add brake fluid to the reservoir up to the MAX mark.
13.
CAUTION: Failure to bleed the brake system in the correct sequence can seriously affect braking performance.
Repeat the above procedure to bleed each brake caliper.
14. Add brake fluid to the reservoir up to the MAX mark.
15. Press the brake pedal and check for leaks.
16. Install the cap on the brake fluid reservoir. Connect the electrical connector of the brake fluid reservoir.
17. Install the manifold panel. Secure the clamps.
Comments on this article