Car headlight switch

How to detect the headlight switch failure

The part is to be diagnosed with a multimeter. You should see the car technical manual for the procedure of connection of the device to the contacts, and the nominal voltage or resistance between the corresponding terminals, as the design of the components and their operation principle may slightly vary on different car models. If you do not have a multimeter, you can use a test lamp. If, at a certain plunger position, the obtained readings ​​differ from the values specified in the manual, or the test lamp does not go on, or it is constantly on, the component needs replacement.

You may identify that the headlight switch needs to be checked by the following signs:

• low or high beam, parking lights or turn indicators do not work;
• headlights do not turn off;
• lamps light up for several seconds and go out;
• headlights do not work in all modes (for instance, they respond only to the high beam flash activation);
• when you switch on the parking lights, the fog lights begin to flicker;
• a smell of burnt plastic appears in the passenger compartment;
• the headlight switch lever jams;
• the lights switch off spontaneously when driving on a rough road.

Causes of the headlight switch faults

The most common switch failure is the contacts burnout. Typically, it is the result of extreme temperature rise due to the loose connectors, voltage drops in the circuit, or a short circuit. Usually it is accompanied by the housing surface melting and the appearance of abnormal smells in the vehicle passenger compartment.

The electrical signal passage is also hindered by the contacts oxidation that appears due to the impact of moisture and dirt. The connection in the contact block can also be impaired by the extensive wear of the sliders, their driving disc, and also the switch lever. Similar effects result from mechanical damage to the spring mechanism or the movable contact.

The component housing or its fasteners are usually damaged due to excessive force applied during installation. Loss of tightness of the housing is dangerous as it leads to ingress of moisture and dirt with all the consequences that come with it.

Sometimes it is necessary to replace a serviceable switch. Usually, this should be done due to erasure of the pictograms on the switch lever, so that the driver has to turn on the corresponding devices blindly.

Replacement of the headlight switch

You can easily replace the headlight switch on your own. For this follow the procedure below:

1. Dismantle the instrument panel frame and the protective cover that is located under the steering column.
2. Release the clips and pull the part out of the mounting seat. On some vehicles there is no need to open access to the internal part of the switch. It is sufficient to press it into the instrument panel, turn it clockwise and pull it towards yourself.
3. Disconnect the wire terminal block from the switch and replace the latter with a new one.