ABS is a standard fitment on the models in discussion and utilizes a fail-safe system and this means that conventional brakes will always work even if the ABS system fails. The system inhibits wheel locking by adjusting hydraulic pressure in the brake circuits; the anti-lock operation of a vehicle manages the braking force at each of the wheels by means of sensors that detect the speeds of rotation of the wheels. When a fault happens, testing is possible only with professional tools that can be found at a Nissan dealer, and owners should not attempt to use basic workshop tools for diagnosing complicated ABS problems. Before replacing the component, it is necessary to safely raise the body of the vehicle and to untighten the nut of fastening of the roadwheel, which is necessary for a given component. Front wheel speed sensors are installed on the rear side of each wheel hub carrier; whereas rear sensors are fitted on the inner face of the hub/stub axle assembly. Remove the front wheel arch liner while to get the access to the front sensor connector, follow and cut the wires from the support brackets to the sensor. The last step is to take out the retaining bolt to unlock the sensor, use of penetrating fluid may be necessary at this stage. Refitting requires that the mating surfaces should be free from dirt and grease, application of anti-seize compound as well as tightening the retaining bolt to a certain torque. The hydraulic modulator is located on the passenger's side of the front side of the car; turn off the car's battery, unscrew some screws to release fluids and remove the air cleaner. This is done, by removing the wiring plug connecting to the modulator, identifying and removing the brake pipes, as well as taking off the modulator and the supporting bracket. To refit place the modulator onto the mounting bracket and tight the bolts, and finally bleed the brake system.