A roof dome light wiring is a vital feature in any car. It provides much-needed illumination when you enter or exit your vehicle, especially during nighttime.
One of the easiest and most reliable ways to control the dome light is to wire it to the door switch.
This ensures that the light automatically turns off when you close the door and turns on when you open it.
If you want to learn more about the roof dome light wiring, follow this detailed guide!
Table of Contents
- Understanding the roof dome wiring
- Important components in the dome light wiring circuit
- Why the dome light will not turn off when the door is closed
- Why can’t my dome light turn on when the door is open
- How to wire a dome light to a door switch
- Final Thought:
Understanding the roof dome wiring
The vehicle’s roof dome lights illuminate the inside of an automobile (car, bus, truck, etc.).
Normally overhead-mounted dome lights usually provide switchable OFF, ON, or AUTO lighting.
Automatic dome lights turn on when you open the door of the vehicle and automatically go off when you close the door.
The lights may also turn on when the vehicle engine is powered off.
The dome light shell features three connectors. The first one goes directly to the ground.
The second connects to the battery, and the third one connects to the dome light switch, which is controlled by the door switches.
These switches are connected to the ground directly in parallel.
Important components in the dome light wiring circuit
Here are the components to connect to your dome light wiring circuit:
1. Dome lights
Most automatic dome lights are designed to dim rather than cut off to assist your eyes adjust.
The car’s roof dome lights may offer brighter illumination compared to overhead courtesy lights for tasks like reading a map or writing a report.
For specialty applications, a dome light can offer colored lights like green, blue, or red instead of white.
The roof dome light replacements come in different materials, shapes, and harnesses for the car’s electrical system.
Some require replacing only the light bulb (lamp), while others need to change the whole assembly.
Some states and countries have laws requiring all passenger vehicles to have dome lights so they can pull you over for having a burnt-out or faulty dome light.
Regardless, dome lights make perfect camping night lights.
Generally, dome light bulbs range from 15W (H15/5W) to 25W (HB2). The 15W bulbs are often found in small vehicles, while the 25W bulbs are in larger vans and sedans.
Two or more types of bulbs can be used in some domes. That is why we recommend checking your vehicle manual if you are unsure about the type of bulb your dome takes.
2. Door jamb switch
A door jamb switch refers to a light switch mounted in a door. The two most common locations for jamb switches are refrigerator doors and vehicle doors.
Replacement dome jamb switches are made by several manufacturers and are often sold with door components and accessories.
Generally, a dome jamb switch switches on the light when the door is opened and turns off the light when the door is closed.
It has a tiny mechanical component that moves when the door moves, closing and opening the circuit.
Typically, dome jamb switches are very tiny because they need to fit in a compact space.
The light may have a manual switch setting option where more operational control is needed. It may also be solely controlled with the switch.
Dome jamb switches activate the dome light in cars when the door is opened or closed to assist drivers as they exit and enter their vehicles.
On some car models, the light stays turned on for a set period of time after the door is closed to offer ambient safety for the driver.
That’s because some switches include an “override” feature that enables them to stay on standby even after shutting off the main power.
Why the dome light will not turn off when the door is closed
Here are the causes and troubleshooting tips for the dome light that might fail to turn off after closing the door of your truck or car:
Check and see if your dimmer switch is on
If your car has a dimmer switch, it should be already turned on. If so, you will only need to adjust the dim settings.
Find and test the dome light switch, which can be a latch switch or a button switch.
Locate a push button switch around the door frame or on the door jamb.
If you don’t find such a switch in your vehicle, use a screwdriver to pull the door latch to check if the latch turns it off.
The switch fails to work, the interrupter, a part of the switch, should be blamed rather than the wiring.
If the switch turns off lights, then the condition of the car door may be keeping the dome lights on.
Check the door latch, the striker, and the door hinges if the switch works
If the door is misaligned or has loose hinges and sits improperly, it will not latch in completely. The switch will also not turn off because the latch isn’t interrupting the circuit.
If you have to slam the door unusually hard to switch off the dome light, it is a sign that the hinges are bad.
You can check the door hinges by grabbing the bottom of the door using an assistant and lifting it up and down. Next, check the hinges to confirm if they are loose.
Check the door latch and striker for obvious, visible damages, as there might be rubbing damage on both.
This will be a sign that the latch has been hitting up against the striker, thus damaging the door latch over time.
A Car door latch
Check if the dome light was left on.
Depending on the type of your dome light, check if it was left on. It could be a push dome light or might have a switch that allows you to make changes to the settings.
Why can’t my dome light turn on when the door is open
If your dome light fails to work at all, it could be due to an electrical problem. Here is how you can fix this issue:
Check the dome light connector and bulb.
Remove the lens of the dome light and check for discolored or black glass or burnt-out filament. If this is the case, then your dome light bulb is bad, and you should replace it.
Test the power at the dome light.
If the dome light still does not work after replacing the dome bulb, use a power probe, such as the test light, to test your dome light.
If there is power and the power probe lights up, then there is a problem with the bulb’s connector points or the dome bulb itself.
Check the relay or fuse.
If the power probe fails to light, then there is no power at your dome light. Typically, a fuse or a relay will be the problem.
So, you should check the fuse as it is most probably burnt. If not, the issue could be the door or the switch.
How to wire a dome light to a door switch
The following is a step-by-step guide to wiring a dome light to a door switch.
The required materials and tools
- Electrical tape
- Wire stripper
- Flathead screwdriver
- Solder and soldering iron
- Circuit tester (optional).
Step 1: Before you begin
Switch off the main power to your vehicle before starting work. If you do not know where the dome light is located, check your vehicle’s manual.
Pry off the cover of the dome light housing using a flathead screwdriver.
Remove the old bulb by pulling it out of the socket carefully.
After removing the old bulb, check your car’s manual for more details on returning the dome light bulb.
Remember, a dome light light bulb is fragile and can be expensive to replace. So, be careful not to break it.
Step 2: Find the door switch.
Follow the wires from the dome light to locate the door switch. Every wire connects to a terminal on top of a black box, which is located near the fuse box or above the glove compartment in your car.
There should only be one wire going to each terminal.
Determine which wire connects to which terminal using a circuit tester. Door switches are designed to be easily tested using multimeters. You can also use a regular cell phone if it has an analog meter app.
A vehicle door switch panel
Step 3: Identify the number of wires that require splicing.
To wire a dome light to the door switch, you must cut the existing wires very close to the terminals.
The number of wires required to splice will depend on the dome light and your particular vehicle. For example, a car with a 2-wire system will only allow you to switch one of the two wires simultaneously.
On the other hand, a car with a 3-wire system will allow you to switch either wire for the new dome light.
Step 4: Splice the wires together.
To wire a dome light, first remove the insulation from the wires using a wire stripper. Next, twist the wires together using your fingers until you achieve a tight fit.
Then, solder the twisted ends and insulate them using heat-shrink tubing or electrical tape to prevent short circuits. You can also use wire nuts if you have them.
The dome light has a negative and positive polarity, which works only when wired correctly.
The negative and positive sides of a vehicle’s dome light are usually colored black and red, respectively.
To achieve the correct wiring of the dome light, check your schematic diagram and manual of your car model.
Step 5: Put the plastic cover back into the housing of your dome light.
You should be careful not to break anything. Next, turn on the power and press the door switch to test your connection.
If you notice any issue with how your connection works, re-do some of your wire splicing or soldering. You may also want to revisit your entire work.
Step 6: Test the functionality of the dome light.
Test the light’s functionality before attaching the cover. If it functions as expected, then replace the cover and enjoy your new and improved dome light.
If you carefully follow the steps discussed in this guide, you will easily wire your car’s roof dome light to the door switch.
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We deal in all types of automotive wiring harnesses and cable assemblies, offering custom designs to suit your dome light needs.