Car Brake light switch

How to detect the brake light switch failure

To check the switch operability, disassemble it. Then connect the ohmmeter to the corresponding terminals and measure resistance between the contacts. It must be equal to zero. Then press the switch button and evaluate the gauge readings: they must tend to infinity. If the values received as a result of measurements do not match the nominal ones, the brake light limit switch needs replacement.

You may identify that the brake light switch needs to be inspected by the following signs:

• the brake lights are constantly on or turn on with a delay;
• the on-board computer signals an error;
• the engine is running in emergency mode;
• engine power has decreased;

Causes of the brake light switch failure

Most switch faults are caused by moisture and dirt getting into the housing. This leads to oxidation and jamming of the movable contacts. Besides, poorly connected contacts are subject to burn out.

In many cases, the switch malfunction is due to the return spring slackening or kink. In such a case, when you try to adjust the switch plunger, you will not hear the specific clicks. Eventually, moving contacts can wear out: if ​​their contact area is too small, the switch cannot operate correctly.

In some cases the cause of this can also be in wrong adjustment. The clearance between the switch housing and the switch plunger tip must not exceed 0.2-0.5 mm. If it is lower, the stop lights are constantly on; if it is higher, the lights switch on with a delay. Increase of the adjusted clearance is caused by the pedal vibration, its wear, or wear of the switch plunger; while the clearance decrease is caused by unqualified repair.

Replacement of the brake light switch

The part is not repairable. If a fault occurs, replace it. Even an inexperienced car owner can install a new switch. For this you have to stick to the following procedure:

1. Switch off the ignition.
2. Disconnect the wire connector from the part.
3. Loosen the lock nut.
4. Remove the switch.
5. Pull the pedal towards yourself as far as it can go.
6. Mount the part on the bracket.
7. Adjust the clearance with the help of the clearance gauge.
8. Tighten the lock nut, carefully holding the switch housing.