Test Step 4.1

Test 4.1:

Vehicle speed above 100 km/h or during long trip: ABS lamp ON, ASC display OFF, PALA ON:

- Check 55-pin connector that it is firmly fitted and connected correctly at the ABS/ASC control unit. Check 13-pin connector that it is firmly fitted and correctly connected at the ABS hydraulic unit.
- Check hydraulic unit connections in accordance with schematic for continuity.
- Check valve relay, see Test 3.1
- Check engine relay, see Test 3.1
- Check valve resistance in hydraulic unit.
- Valve FL - Pin 4 and Pin 21 0.8 - 1.9 Ohm
- Valve FR - Pin 4 and Pin 37 0.8 - 1.9 Ohm
- Valve RL - Pin 4 and Pin 19 0.8 - 1.9 Ohm
- Valve RR - Pin 4 and pin 2 0.8 - 1.9 Ohm

If the valve resistance is greater or less - at all four valves:

- Check wire 4 to hydraulic unit connector wire 4 - <1 Ohm
- Diode check with Service Tester Multi meter (see BMW Service Tester Operating Instructions)
- Blocking direction Pin 6 (+) to Pin 4 - direction of flow Pin 4 (+) to Pin 6-
- at FL valve: - Pin 21 to hydraulic unit connector Pin 1 <1 Ohm
- at FR valve: - Pin 37 to hydraulic unit connector Pin 3 <1 Ohm
- at RL valve: - Pin 19 to hydraulic unit connector Pin 5 <1 Ohm
- at RR valve: - Pin 2 to hydraulic unit connector Pin 7 <1 Ohm

Check resistance directly at the hydraulic unit (see schematic).

If necessary replace hydraulic unit.