Removing Brake Booster

WARNING: This page is about a different car, the 2010 Porsche Cayenne, 2009 Porsche Cayenne, and 2008 Porsche Cayenne. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Brake Booster

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Information

During assembly work on hydraulic connections, the electrical plug connections on the hydraulic unit must always be connected. This prevents the plug connections on the hydraulic unit and the inside of the connectors being splashed with brake fluid or water.
Damp connectors must be wiped dry before disconnection.
Brake fluid on electrical contacts (even thinned brake fluid) leads to corrosion and may cause faults in the system.

The brake master cylinder is located on the left in the engine compartment, under the cowl panel cover -arrow- , together with the brake booster.

Fig 2: Identifying Brake Master Cylinder

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Information

Brake lines are to be sealed with suitable plugs.
To catch escaping brake fluid, place a cloth under the brake booster.

Push both connectors -arrows- on the plenum panel (oxygen sensor cable) from the bracket.

Fig 3: Identifying Plenum Panel Connectors (Oxygen Sensor Cable)
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Open the cable clip on the plenum panel and loosen the cable.
Remove left plenum panel partition.
Partly remove the brake master cylinder (brake fluid reservoir) → Removing The Brake Master Cylinder .
Disconnect the vacuum line on the brake booster.
Disconnect the connector from distance sensor of the brake booster -arrow- .

Fig 4: Locating Distance Sensor Connector
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Unclip the cable over the brake booster from the holders -arrows- and pull upwards.

Fig 5: Locating Brake Booster Cable Holder
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Unclip the brake line to left front wheel out of the bracket underneath the relay carrier.
Remove the brake master cylinder → Removing The Brake Master Cylinder .
Loosen two M6 screws on the lower closing panel -arrows- (upper screw head covered) (shown here when fitting the brake booster, relay carrier removed).

Fig 6: Locating Lower Closing Panel Screws
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Information
- If the rubber bushes stick to the holders in the plenum panel when removing the relay carrier, these must be fitted in the openings provided before being inserted again.
Release the relay carrier in the plenum panel and hinge it to one side. To do this, unclip the six plugs in the rear section of the relay carrier (-arrow- and right marking).

Fig 7: Locating Relay Carrier
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Remove the cover under the dashboard on the driver's side in the passenger compartment → Removing front trim (engine compartment) .
Pull off connector of stop light switch -arrow- and remove the complete holder. .

Fig 8: Locating Stop Light Switch Connector
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Information
- When loosening the pushrod of the brake booster with the unlocking tool T10189 from the pushrod of the pedal, the tool must first be inserted and then the brake pedal pulled out into the passenger compartment.
Release brake pedal from pushrod -arrow- of brake booster with unlocking tool → Removing brake pedal .
To do this, insert the unlocking tool T10189 from below into the bush on the brake pedal -arrow- .

Fig 9: Identifying Unlocking Tool (T10189)
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Fig 10: Locating Brake Pedal Pushrod
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Remove the four M8 lock nuts on the brake booster in the passenger compartment.
Remove front left wheel housing liner.
Disconnect the brake line in the wheel housing on the intermediate piece -arrow- and seal with suitable stoppers.

Fig 11: Locating Brake Line
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Remove both clips for the air-conditioning lines in the plenum panel.
Pull the brake lines to the brake master cylinder and left front wheel carefully forward and press the air-conditioning lines down. Make sure that the boot on the brake booster -arrow- does not get stuck in the duct to the cabin.

Fig 12: Locating Brake Booster
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Carefully pull out the brake booster -direction arrow- to the front.

Fig 13: Pulling Out Brake Booster
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