Booster Bleeding

Any time air is allowed to enter the brake system, due to damage or service, the system must be bled. Air in the system will not cause a spongy pedal, but instead may cause a trouble code to appear.

When bleeding brakes, maintain an appropriate level of DOT 3 brake fluid, and do not allow the pump/motor assembly to run continuously for more than 60 seconds. If it becomes necessary to run the pump for more than 60 seconds, allow it to cool for several minutes before running it again.

Booster Bleeding
1. Depressurize hydraulic accumulator as follows:
a. Disconnect battery ground cable, and ensure ignition is in the OFF position.
b. Pump the brake pedal at least 25 times with about 50 lbs. of force. A noticeable change in pedal feel should be evident.
c. When a definite increase in pedal effort is felt, pump pedal a few more times to remove hydraulic pressure from lines.
2. Connect negative battery cable.
3. Make sure all brake lines and hoses are tight, and fill fluid reservoir.

Fig. 47 - Bleeding Brake System:

4. Connect a transparent hose to the bleeder screw and place the other end into a clear container to hold brake fluid.
5. Open bleeder screw 1/2 - 3/4 of a turn.
6. Turn on the ignition switch to force fluid out the open bleeder. When the fluid flowing from the tube is free of air bubbles, turn off ignition. If fluid does not flow when ignition is turned on, the pump may need to be primed. First try shaking the pump return hose, with the ignition still ON to break up air bubbles. If necessary, turn OFF ignition, remove pump return hose at one end, fill with brake fluid and reconnect. Attempt bleeding operation again.
7. Remove bleeder hose, and torque bleeder screw to 7.5 lb-ft Do not over torque.
8. Top off reservoir to correct level, then turn ignition on to allow pump to charge the accumulator. The pump should stop after about 30 seconds.