Test 09 - Hydraulic Unit, Pressure Release

TEST SEQUENCE
1. Connections needed:
- T-plug (4a) with adapter (A) at Antilock Brake System (ABS) wire harness (1)
- T-plug (4b) at ABS control unit (2)
- Connecting lead at adapter (A) to cigarette lighter - red telltale lamp comes "On"
2. Rear axle on BPS and flashing "*" on tester for REAR L/R.
3. Switch "On" ignition; note voltage between leads 1 and 10 (if necessary, run engine at idle speed). Switch "On" brake dynamometer for both wheels.
4. Apply brakes until BPS reading is 2000 N (charge axle if nec.), and maintain this pedal force steadily.
5. Press acknowledge button. After 2 sec. the pump (RFP) is started, the valve opened briefly and brought to the main phase, and the "S" display starts to run. When 3 sec. are displayed, press the acknowledge button; end of measurement.
6. To repeat, press acknowledge button; pass on to next wheel (down arrow). Test positions: REAR L/R, FRONT L/R.





Nominal Values

7. Compare the displayed actual values obtained from the test equipment with the nominal values provided above. If nominal values are not obtained, proceed with the troubleshooting procedures below as needed.

TROUBLESHOOTING
Voltage Between Line 1 And 10
- Switch "On" ignition.
- Run engine.

Recharge, check battery.

Front Left - Right - Right/Left Rear Left - Right - Left/Right
- Due to high inrush currents, repeat test step with engine running.
- Refer to test step 05/06/07.
- A prerequisite for the ABS test is that the conventional brake system is in working order - System well bled, no leaks at brake line connections, brake pads OK., master and wheel brake cylinders OK.
- Ensure uniformity of wheels on one axle.

Brake line at hydraulic unit Y1 interchanged.
Replace hydraulic unit.