The headlight switch, commonly known as the dimmer switch, is the electronic switch that is responsible for controlling the vehicle’s headlight functions. They are mostly found as a part of the combination switch lever that is usually mounted on the steering column, however they can also be found as buttons or knobs mounted on the interior of the vehicle. The switch generally controls the vehicle’s interior lights, the running lights, the low beam headlights, high beam headlights, and in some vehicles the automatic headlight system.
Symptoms of a Bad or Failing Headlight Switch
If the high beams, daytime running lights, or headlamps are not working consistently, you might need to replace the headlight switch.
As with any electrical switch, with regular use, it might eventually wear out and need to be replaced. Mostly, a bad or failing headlight switch will produce a few symptoms that can alert the driver of a potential issue.
1. Issues switching between modes
One of the most popular symptoms of a faulty headlight switch is issues switching between headlight modes. If the headlight switch fails or wears out it can lead to problems operating the headlights. A broken switch might only work on certain modes, or even cause them to come on and off intermittently and erratically. Any type of problem with the vehicle’s lights can become a safety hazard due to the decrease in illumination and visibility.
2. Issues with the high beams
Another symptom of a bad or failing headlight switch includes issues operating the high beams and more specifically, issues keeping the high beam engaged. Most headlight switches work by pulling the lever backwards and locking it into place to activate the high beam headlights. Over time however the switch can break, which result in issues keeping the high beam headlights turned on. A broken switch might still be able to turn the high beams on, however a faulty switch may pop loose and cause the high beams to disengage.
3. None of the lights work
Another symptom, one of more serious issues, is that vehicle lights do not work at all. If the headlight switch completely fails it might prevent all of the vehicle’s lights from functioning. You may notice that when you go to turn on the headlights, none of the modes will turn on any of the lights. A vehicle without any functioning lights is not safe to drive and especially in low light and night time situations.
How to Replace a Headlight Switch
If your low beams do not activate or if your lights just won’t come on at all, it’s likely time to replace your car headlight switch. This is a general problem on cars of all makes and models, and the repair can be done in your garage rather than handing over the money to a mechanic.
1) Disconnect the negative cable from your battery and wait for 5 to 10 minutes to allow the capacitors for the airbags to discharge.
2) Remove all the screws around the switch, or pry the retaining ring that helps to hold the switch in place away from the dash.
3) Slide the switch out of the dash carefully and after that, remove the wire plugs. Attach a spring clamp onto the plugs for keeping them from falling into the dash where they are difficult to fish back out.
4) Pull the light switch into the on position, press the headlight case button and then remove the switch. Use a screwdriver helps in case your car has more than one release button. You might have to remove a nut at the bottom of the switch shaft to remove the decorative bezel.
5) Insert the new car headlight switch into the housing and replace the bezel and shaft nut if required.
6) Attach the wire plugs while taking care not to bend any contacts. Slide the housing and switch back into the dash and make sure that the connecting wires don’t bind.
7) Put back any trim and mounting screws before you reconnect the negative battery wire. Test the switch as well as the low and high beams.