A sunroof is a fantastic and luxurious addition to any car. It makes the interior airy and lets in more light giving you the illusion of a bigger cabin. However, even though they are fun, most have an opening mechanism that might go wrong somewhere down the line – especially if it’s electric.
If you are lucky, your sunroof will fail gradually. It will start working slowly or working intermittently. If you are unlucky, it will fail to open or close without prior indications of failure.
While a jammed shut sunroof is something you can live with for days or years, a sunroof stuck open is an emergency.
How Does a Sunroof Work
There are two types of sunroofs. The working varies depending on what kind your car has.
A Manual Sunroof
Manual sunroofs are pieces of glass on sliders and a pivot or two, depending on their complexity.
You operate it by manually pushing on a slider that slides it away and out, just as you would open a manual window in your house.
The only moving parts of the system are the slider and the hinges. While manual sunroofs are deemed less luxurious, they tend to last longer since they are mechanical installations without complexities like motors, gears, cables, and hydraulics.
How Does a Power Sunroof Work?
Cars with power sunroofs are easier to operate. A push-button or switch in the vehicle activates an automated circuit that opens and closes the sunroof on demand making it very similar to a power liftgate.
Most cars use an electric motor and a set of gears, levers, and sliders to drain the roof open or closed.
A motor controller interprets the input from the controller button. It determines if:
- You have activated the full automatic open or close. This moves the motor continuously, even with your finger off the motor
- You have activated partial open or close that drives the motor only when the switch is closed (pressed in)
Car manufacturers create self-contained units that rarely require any maintenance. There is nothing to maintain, and the unit doesn’t go wrong unless it receives direct impact – or your car is very old.
This doesn’t mean that your sunroof won’t fail at one point or another. Here are some common things that could make it remain stuck open or fail to open.
There’s Debris in the Run Channels
The most common problem that could stop your sunroof on its tracks (literally) is debris on the tracks.
If you park outside or under a tree, tiny bits of leaves and twigs could get lodged into the sunroof’s channels. As the sunroof slides along, it could encounter debris that is too big to push through.
The motor goes into protect mode and stops trying to push the sunroof through. This could leave your sunroof partially open or closed. At other times, it will leave it jammed fully opened or closed.
You will hear the motor kick in and fail to move the sunroof before cutting out or before you decide to stop trying. Even if you don’t have these tell-tale signs of blockage, you can still clean up the sunroof for good measure.
ProTip: Such a failure will happen when the sunroof is in operation. You will hear the motor struggle to keep the cover moving but fail as it gets stuck.
How to Diagnose and Fix a Clogged Sunroof
Luckily, troubleshooting and fixing this problem is simple.
- Park your vehicle on a flat ground
- Get a ladder or a stepping stool so that you can access the roof safely
- Clean the top of the car (or the entire vehicle) using a power washer or water and a bucket if you don’t have a power washer
- Try to open the sunroof. If you are lucky, the wash could have dislodged the debris and fixed your problem
- If not, inspect the sunroof rails for any debris. Look for any bits of debris, especially towards the end of the rails
- Use a plastic scraper, some paper towels, and a degreaser to get rid of any dirt, debris and hardened grease
- After thoroughly cleaning and getting rid of all gunk, try running the sunroof again
This should fix your sunroof if the problem were jammed rails. If you have a powered sunroof, you can investigate further. Get an expert to help you disassemble and troubleshoot the assembly’s moving parts again if it’s manually.
A Blown Fuse or Relay
Like any other electrical system in your car, the power sunroof has a fuse protecting its circuit just as it is the case for your headlights and other electronics. If this fuse blows, your sunroof will go silent. Get your fusebox’ schematic and identify the fuse on your sunroof’s circuit.
Pull it out and check if it’s blown. If it is, replace it and monitor the system closely. Fuses shouldn’t blow unless there’s a problem in the circuit. If there’s an issue in the wiring or with the motor, the fuse will blow again soon. If that happens, have the entire circuit inspected.
While some manufacturers run the entire circuit on full power, others use a switching relay – especially if your car has a software switch activated from the infotainment system.
If this is the case, identify the relay and check that it’s working fine. A dead relay won’t send power to the sunroof’s motor.
A Failed Switch
All the triggers in an electric sunroof start with the press of a switch. If this switch is faulty, then your sunroof won’t work at all.
A promising sign that this is the case is you won’t hear the sunroof motor kick on. Troubleshooting this problem might need more than a regular car owner has. You will need to disassemble the area around the switch and have a multimeter at hand.
Troubleshooting Your Switch With the Infotainment System
If you have a modern car with software controls, chances are you can also open the sunroof from your infotainment system or car computer. Check out your manual and infotainment menu. Try activating it from there. If it works, chances are your switch is the problem.
How to Troubleshoot a Failed Sunroof Switch
If you can’t use the software approach to troubleshoot your switch, you will have to remove the trim covering your button.
- Expose the terminals at the back of your sunroof controller switch
- Turn on the car to ensure there is the power to the systems
- Use your multimeter and probe different wires to find the ground and +12V terminal (or reference voltage, often +5V if your car uses CAN bus or software actuation) and ensure they have power. Use can use a repair manual to get the pinout faster
- Activate the switch by pressing it while probing different terminals to see if there is a change in voltage with reference to the ground
- If there is no change, try jumping the open signal terminal to the power input terminal (+ve voltage) and see if this activates the sunroof
- If it does, consider getting a new switch
ProTip: Troubleshooting the switch can be overwhelming. Leave this to a mechanic if it’s your first time working with electronic circuits. If jumping the button doesn’t activate the sunroof, then the problem is something else.
A Damaged or Overheating Motor
Since the motor is the powerhouse behind your automatic sunroof, any dip in performance, overheating, or damage will affect your sunroof.
Even though these motors rarely fail, age, overuse, and weather ravishes could push your motor beyond its tolerances. If this happens, the motor will:
- Overheat frequently, forcing it to stop or be less efficient hence slowing down or stopping the opening and closing procedure completely
- Fail to kick in since brushes or the armature is worn out
- Other forms of mechanical or electrical failure in the electric motor
A damaged motor will either go down silently or take a fuse with it. If your system keeps blowing a replacement fuse and doesn’t work efficiently or at all even after replacing the fuse, chances are the motor is damaged and drawing more current than it should.
Stop trying to use the power sunroof and have the motor replaced. Frequently swapping the fuses won’t make a difference.
How to Tell if Your Sunroof Motor is Bad
The primary things to look for are:
- The sunroof fuse keeps on blowing even after replacing it
- There is no whirring sound from the motor even though you can detect 12V power at the motor’s terminals
- The sunroof motor kicks in intermittently or works very slowly even when the car’s engine is running
Warning: If your power sunroof keeps blowing a fuse and still works after replacement, avoid the temptation to use higher-rated replacement fuses. This will overheat the wiring causing more problems.
A Broken Mover Slider or Cable
The final puzzle piece that could go wrong is the set of gears, belts, and sliders that transfer power from the motor to the sunroof in a fashion slightly similar to what happens in your power windows.
Access to these components varies depending on your sunroof’s design. Either way, this will need some tools and efforts to open the system and inspect it.
Sometimes, you could be lucky and find that just a belt has slipped off or some gears are out of place. Otherwise, you will also need to buy replacements to fix the problem.
Were You Involved in an Accident?
A common problem that could make your power or even mechanical sunroof fail is an accident that translates pressure to your car’s roof. While most accidents like this will shatter the glass, some could disfigure the panels around the sunroof or damage the motor.
Get your sunroof thoroughly inspected if it fails after an accident or something fell on your car’s roof. Someone stepping on the roof during a party (or for any other reason we don’t know) could also damage your roof.
What is the Difference Between a Sunroof and a Moonroof
Modern cars will either come with a sunroof or a moonroof. While the two mean some form of opening on the roof of your vehicle, there are some subtle but noticeable differences.
A sunroof is an opening on the roof covered by glass or metal that slides open and even pops open to reveal the sky. It can get out of the way entirely, leaving enough space for someone to poke their head through (don’t do this in a moving car)
A moonroof, on the other hand, is a glass car roof. The glass is often intent and has some form of blind or curtain that you can draw shut or open to expose the outside. Some moonroofs tilt open to let in some air.
Sunroofs are a good idea in summer since they can open fully, and you can pop your head through them – hence the name sunroof. Moonroofs, on the other hand, give you the view and not much wind.
The sun will heat your car fast when you open the shade in the daytime. They’re called moonroofs since they let you enjoy the sky (and the moon) to the fullest at night without worrying about the sun’s heat.
Observation: Moonroofs are often more significant than sunroofs since the glass doesn’t move, making it easier to fit more enormous panes of glass without figuring out where to hide them when they open up.
Do Sunroofs Weaken a Car?
Sunroofs don’t necessarily affect your car’s rigidity. After all, the roof panel isn’t a structural part of the car. The load-bearing pillars that protect you in case of a roll are to the sides.
Moreover, manufacturers use tempered glass, which is as strong as your windshield. Though strong, your sunroof is still a technical weak point to your car. Some of the weaknesses they introduce include:
- Damage from falling objects will be more fatal. While metal sheet roofs can be dent repaired, a glass sunroof will shatter and need replacement.
- The fact that sunroofs fail to introduce another component to repair, which is technically a maintenance weakness.
- The seals around your moonroof could fail, making your car’s roof start leaking.
Why Won’t My Sunroof Auto Close or Open
If your power sunroof has an auto-open or auto-close button that opens or closes it entirely, you expect this to happen every time you press the right button.
Sometimes, this won’t happen if there is a problem in the controller circuit or the controller has forgotten the setting. Just like your automatic power windows, the sunroof controller needs to relearn the open and close positions before it can start running automatically.
- Get into the car and lock the doors
- Turn on the car
- Press the sunroof open button and hold onto it until the sunroof is fully available. Keep the button pressed for around five seconds.
- Press the close button and hold onto it until the sunroof is fully closed. Keep the button pressed for around five seconds.
- This should reset the system in most cars. Try the automatic controls and see if they work.
Some cars will only accept a reset if the vehicle is in the ON position but not running. You can retry this if the above procedure doesn’t work. Consult your car’s manual for further instructions on resetting the system if the above common procedure doesn’t work.
Can We Add a Sunroof to a Car?
While possible, installing an aftermarket sunroof is an expensive and involving endeavor.
You will need a professional to cut a hole through your car’s roof, reinforce it, get a compatible sunroof mechanism, install it and seal the opening to weatherproof it. A professional aftermarket sunroof that won’t affect your car’s resale value is expensive.
Is it possible? Yes. Should you do it? Perhaps not. Buying a car with a sunroof already is a better way out.
Bottom Line
A sunroof is a fantastic addition to your car – if you use it. Some people see it as a liability. Others will love it, cherish it and use it whenever they can when cruising the open roads. Either way, keeping it in good working condition is paramount if you want to keep enjoying it.