Important: Before replacing the hydraulic unit, check whether:
- ground is connected to control module connector PIN 16 (from ground point 2) The locations of the ground points are shown on the wiring
diagram Ground points. See: Brakes and Traction Control/Antilock Brakes / Traction Control Systems/Locations/Ground Locations
- plus (vehicle voltage) is connected to control module connector PIN 17 and PIN 18.
- the plug connection on the return pump is OK.
Test Point 13
TEST POINT 13
Stop Light Switch
DTC 4340
- Check with the System Tester 2 via the "Input signals" menu. Press the brake pedal after selection of the stop light switch.
Required display: Display in screen changes from "not actuated" to "actuated".
- Pull off wires on the stoplight switch (No. 1). Test the stop light switch with a multimeter (remove switch for the test if necessary).
- Check stop light switch adjustment (operating point).
- Check wiring according to the wiring diagram.
Test Point 14
TEST POINT 14
Wrong Gear Wheel
DTC 4225
The ABS gear wheels possess 48 teeth. Not all 48 teeth are detected during a revolution of the wheel.
- Check ABS gear wheels (clamping pins on the front axle / pulse strip on the rear axle) for dirt or damage.
Replace damaged parts.
- Check wheels and tyres (extreme tyre differences or impermissible wheel/tyre combination).