Test 09 - Hydraulic Unit, Pressure Release

ABS Test Equipment:

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 with down arrow button.
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 1500 N (charge axle if necessary) and maintain this pedal force steadily.
5. Press acknowledge button. After 2 sec., the pump (RFP) is started, the valve opened brief and brought to the main phase, and the 's' display starts to run. When 5 sec. are displayed: press acknowledge button; end of measurement.
6. To repeat, press acknowledge button to move on to next wheel, press down arrow button. Test positions: REAR L/R, FRONT L/R in any desired order.





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 Wires 1 And 10
- Turn on ignition.
- Run engine.

Battery charged (check).

Front Left, Right, Left/Right - Rear Left/Right
- Due to high switching on power, possibly repeat test step with engine running. Refer to test steps 05/06/07.
- Testing the ABS requires the conventional brake system to be okay: bled properly, brake line connections tight, brake pads okay.
- Watch uniformity of wheels on one axle.

Replace hydraulic unit.