Factory sunroofs are becoming more popular and more sophisticated – and more intimidating. Larger roofs on some SUVs and minivans can be trouble-free and require little service, but in case of a problem they can be an R&R nightmare.
Before you start pulling a headliner on a vehicle to access a sunroof, you might want to start looking at the repair information first. Most sunroofs are more than just an electric motor and switch that changes polarity. Most late-model sunroof assemblies have their own controller that does a lot more than just move the window up and down. These can determine the position, speed and current draw of the motor.
Uses Of A Scan Tool
On most modern vehicles, the roof is tied together with a serial data bus that will connect with the BCM and other modules. With some scan tools, it is possible to view switch commands. This information can be used for the diagnosis of the switch and motor and can also be used to observe commands to the windows when the door is opened or when the remote is used to open all the windows and sunroof.
Most power windows and roof systems have an anti-pinch mechanism that is designed to prevent the roof from closing on a passenger’s finger, and it controls the express up and down features. Anti-pinch will also activate if there is an extreme amount of buffeting or the roof is closing when the vehicle is going over a rough surface.
The controller or encoder is part of the motor and track assembly and monitors the current draw, speed of the motor and position. An obstruction is detected by current draw and/or if the movement of the roof slows. The control will stop the motors and reverse the movement.
Initializing the Roof
If a regulator or motor is replaced, the new part must learn the position of the window before the window will operate normally. If the window is not initialized, the express up or down feature will not work. In some cases, the window will stop before it reaches the fully closed position.
The initialization procedure typically involves moving the roof from the full up position to the full down position and holding for a set period of time, but this depends on the make and model of the vehicle.
The most common issue with sunroofs is mechanical. Over time, the grease can wash out of the tracks or attract large amounts of dust. This can cause increased effort on the motors and cause the cables to stretch. Some manufacturers even include sunroof maintenance in the regular service intervals.
If a drain is blocked, it can cause water to accumulate and wash away the grease lubricating the tracks. If your borescope is small enough, you can use it to look at the condition of the drains – it can be helpful to make sure the drains are working as part of a repair. Do not use the shop’s compressed air to clean the drains. Often, the compressed air will dislodge the hose in the pillars and cause a leak in the vehicle. Always use a regulated air source not exceeding 30 psi.