In the chassis code M46, on the year 2004 and the models that came later, the brake light switch is set during the pedal setting. This switch is mounted on a bracket toward the top of the
Brake Pedal, on the left side, and the switch on the right is for the cruise control. It illuminates brake lights at the back of the vehicle any time the foot is applied on the brake pedal. To perform the check on the switch, ensure that 4 brake lights light up when the switch is pressed and go off when the switch is released. If the lights do not activate, ensure that the brake pedal is well adjusted and then adjust switch anti-tamper by undoing the locknut and turning the switch in or out until there is a clearance of between 0.012 and 0.039 inch (0.3 to 1.0mm ) from the switch plunger to the pedal stopper without pressure on the plunger before locknut is tightened. When adjusting the strategies, check the clearance it has maintained or not. If voltage is found lacking the switch may not be getting voltage or is defective; diagnose it using the voltmeter or test light to confirm that voltage is present at the switch connector terminal one when the switch pedal is at rest, and it is present at both terminals when the switch pedal is pressed. If there is a zero voltage across both terminals at this moment the switch is most likely to have failed and should thus be replaced. For the switch, you must detach the electrical connector afterwards loosening the locknut and then unscrewing the switch from the bracket; you shall reinstall by tightening the locknut the reverse process must be followed, adjusting the brake pedal and switch to the correct position.