If the indicator light is constantly on, the ABS is not ready for operation. An Opel workshop with the appropriate equipment should find the cause of this phenomenon. Not every workshop can do this, as it requires additional tools and constant professional training of employees, so find out first. As an amateur, you can at least check the plug connectors of the control unit or the speed sensors. Below are some more tips based on our experience with ABS failures:
Left: the speed sensors (arrow) on the left and right are bolted to the steering knuckles with an Allen bolt and read the toothed disk on both drive shafts. The resulting voltage is a measurement value for the speed.
Right: at the rear, the ABS speed sensor (arrow) is integrated into the so-called wheel bearing module.
The figure shows the location of the ABS components, as well as the wiring kits and brake pipe routing:
1 - hydraulic module and control unit;
2 - RPM sensor front right;
3 - ABS indicator light;
4 - speed sensor rear right;
5 - RPM sensor rear left;
6 - speed sensor, front left.
At high speed (from approximately 160 km/h) the ABS indicator light may come on. This is due to the different rotation speeds of the rear and front axle wheels, caused by an unfavourable combination of tyres. This effect does not occur with standard tyres.
If, for example, on ice the front wheels rotate for more than 20 seconds, the control lamp lights up due to the difference in wheel rotation speed.
If the on-board voltage drops below 10 V, the control lamp also lights up. It may also light up if one of the wheels makes a rotation for more than 20 seconds. Then turn off the ignition again and restart the engine.
When ABS is working, it can be felt by the pulsating brake pedal. If it pulsates even during light braking in favorable traffic conditions (aBS warning light does not come on), then this indicates a malfunction.
Tip: Even if the ABS indicator light is constantly on, i.e. the ABS is either disabled or faulty, the car can be driven without restrictions. In this case, the brakes function the same as in a car without ABS.
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