Test 08 - Return Pump

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. Front axle on brake dynamometer (BPS) and flashing "*" on tester for FRONT L.
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 (left and right), and maintain this pedal force steadily.
5. Press acknowledge key. After approx. 5 sec. valve cuts in briefly; after approx. 4 sec pump (RFP) cuts in briefly. After this "COMPLETED" display appears and the reading at the brake dynamometer drops again. After approx. 3 sec., terminate measurement by pressing acknowledge key.
6. Repeat test with acknowledge key; pass on to next wheel with down arrow. Test positions; FRONT L, FRONT R, REAR L. REAR 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 Wire 1 and 10
- Ignition turned "On".
- Engine running.

Battery charged (check).

Front Left, Right, Left/Right - Rear Left, Right, 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, master and wheel cylinders okay.
- Watch uniformity of wheels on one axle.
- Observe relation between wheel - reading.

Brake lines mixed upon hydraulic unit.
Replace hydraulic unit.