Installing Automatic Car Interior Lights: Dimmer Switch

  • 1-2 hours
  • Intermediate
  • 15-50
What You'll Need
Dimmer Switch
Needle Nose pliers
Wrench Set
Neon Tester

Car interior lights can be controlled in many ways. The standard interior lights will come on when a door is open. However there are times when additional light is needed or you want the lights to gently fade. In this case, installing a dimmer switch can be a great tool for your interior lights. Dimmer switches tend to be used specifically for the dashboard lights and the interior lighting. Dimming the lights can reduce glare and make it much easier and safer for the driver.

Step 1. Disconnect Battery

Because installing a dimmer switch will require going into the electrical system, it is necessary to disconnect the battery. Loosen the retaining bolt on the battery grounding wire and disconnect the negative wire from the battery. Make sure the ground cable is secured away from the battery so it will not accidentally touch the battery. Wait for 10 minutes for the power to drain from the wires. By disconnecting the battery there is no danger of being shocked.

Step 2. Remove the Old Switch

It is necessary to remove the old light switch in order to install the new dimmer switch. Locate your interior light switch. The location will vary depending on the vehicle. It can be on the floorboard, on the steering column or behind the dash. Needle nose pliers will help to remove all the nuts that will need to be loosened and removed.

Step 3. The Dimmer

It may be necessary to purchase a dimmer that was built for your car. Make sure you look and have the right one. If this is not an issue then check out what aftermarket dimmer switches are available.

Step 4. Wiring

This should be fairly simply if there is already a wired connection in place. The new switch should already have wiring connector and all that is needed is to connect the new with the old wiring connector in your car. If you do not have a wiring connection then these can easily be purchase at a local auto repair store.

Step 5. Wiring Continued

If you are unsure of which wires to connect to what then it will be necessary to test them. Turn the dimmer switch to the lowest setting. There will be an in wire, out wire, and grounding wire. Tap the lights with a neon tester. Touch the wires that are from the car with the wires from the switch. Normally a green wire is the grounding wire. Attach that to a nearby grounding source. Then test the other wires. The wire that causes your lights to glow is the in wire and the other is the out wire. Connect the wires accordingly.

Common Problems

Many times the interior lights will be connected to the alarm and door locks. Additionally they may also be integrated with the headlights. Sometimes by having the headlight switch fully on this will cause the interior lights to turn on. You also may have computer issues as some vehicle the lights are controlled through the body control module. It will be necessary to check for any fault or error codes.