Bleeding Brakes - Vehicles With ABS and ABS/TC
ABS and ABS/TC
The Boxster and Boxster S are standardly fitted with Solo ABS (3-channel system).
On special request, the Boxster S can be fitted with ABS/TC (TC = Traction Control) up to 2000 model and with PSM as of 2001 model. ABS/TC and PSM = 4-channel system
Bleeding vehicles with ABS/TC differs from vehicles with PSM.
NOTE:
- Observe brake-fluid quality! Use only new DOT4 brake fluid!
- This brake fluid is available under the following part numbers:
Quantity supplied 1 litre = 000.043.203.66! Container quantity 30 litres = 000.043.203.67!
Bleeding procedure
1. Bleed brakes as usual.
2. Subsequently proceed with bleeding the ABD circuit only on vehicles with ABS/TC (4-channel system).
1st step: Bleed brakes as usual
CAUTION:
For vehicles with extremely high mileage or for very old vehicles, damage to the brake master cylinder can occur and the primary boots can be damaged!
- Double the number of pumping cycles and use only half of the master brake cylinder stroke!
1. Fill reservoir to its top edge with new brake fluid.
2. Connect a bleeding device to the brake fluid reservoir. Switch on the bleeding device. Bleeding pressure approximately 1.0 to 2.0 bar.
NOTE: Bleed the outer bleeder valve first!
3. Continue bleeding at the brake calipers in the sequence:
Sequence: Rear right / rear left / front left / front right.
4. Open each bleeder valve until clear, bubble-free brake fluid emerges.
5. Use a transparent hose and a collecting bottle to check the escaping brake fluid accurately for cleanliness, lack of air bubbles and to determine the brake fluid used.
After installing a new brake master cylinder or a new hydraulic unit, observe the following while bleeding:
- Open the right rear bleeder valves, then fully depress the brake pedal several times.
- Hold for 2 - 3 seconds after each depression, then release slowly.
- Repeat this procedure in the sequence rear left / front right / front left. This will remove all air bubbles (from the primary circuit).
NOTE: Also carry out this procedure if the brake hydraulics was largely empty or if after bleeding residual air can be detected by excessive brake-pedal travel!
6. Switch off bleeding device on vehicles without TC (Solo ABS/3- channel system) and disconnect. Correct the brake fluid level if necessary.
7. Proceed with bleeding of ABD circuit on vehicles with Traction Control (4-channel system) (2nd step).
NOTE: In general, the following applies: On vehicles with TC consisting of ASR and ABD (4-channel system), the ABD circuit (in the hydraulic control unit) must be additionally bled when the hydraulic control unit is replaced or removed (2nd step).
2nd step: Bleeding the ABD circuit (secondary circuit) on vehicles with Traction Control (TC)
CAUTION:
For vehicles with extremely high mileage or for very old vehicles, damage to the brake master cylinder can occur and the primary boots can be damaged!
- Double the number of pumping cycles and use only half of the master brake cylinder stroke!
NOTE:
- Bleed brakes as usual!
- Do not carry out return pump activation with the Porsche System Tester 2 until after this has been done (after conventional bleeding)!
- To bleed at rear on right with running pump motor, the bleeding device should remain connected (switched on)! Bleeding pressure approximately 1.0 to 2.0 bar!
1. Connect the Porsche System Tester 2 to the diagnostic socket -arrow-.
2. Switch ignition on. In the ABS / TC system, select the "Bleed" menu.
3. Open the rear right bleeder valve (use hose and collecting bottle).
4. Press the Start button on the System Tester.
NOTE: This initiates certain functions in the hydraulic control unit (return pump, switch-off and switch-over valves are actuated)!
5. Bleed until clear, bubble-free brake fluid emerges.
6. In addition (throughout bleeding operation) fully depress (pump) brake pedal as far as the stop at least ten times.
7. Close the right rear bleeder valve. Then immediately press the Stop button on the System Tester. In this way pump operation is ended.
8. Switch ignition off and disconnect System Tester.
9. Switch off and disconnect the bleeding device. Correct the brake fluid level if necessary.