Scheme 14
General
The sunroof is electrically operated by a three-way switch co-located with the forward interior light assembly. The sunroof drive unit, operating the sunroof panel to the tilt or open positions, is actuated by the integrated sunroof control electronics.
The sunroof frame is bolted to mounting points on the roof panel. The frame, constructed from pressed steel, supports all the sunroof components.
A rubber gaiter is fitted between the sides of the glass panel and drive assembly. The gaiter, reducing wind noise with the sunroof in the tilt position, conceals the drive linkage.
The sunroof drive unit, accessible by removing the motor access panel (integral with the forward interior light assembly), is mounted ahead of the roof segment between the roof liner and lower frame section of the sunroof. It comprises a motor with add-on reduction gear (worm drive), two Hall-effect integral position sensors and integrated control circuit. The software within the integrated control unit is configured to meet individual national regulations. It is connected by a 13-pin multiplug to the P-Bus.
The worm drive drives a gear in a cast housing attached to the end of the motor. The gear has a small pinion gear attached to the outer part of its spindle. The pinion engages with the spiral cables to form a rack and pinion drive. Rotation of the motor turns the pinion which in turn drives the cables in the required direction.
The two cables are attached either side of the pinion. One end of each cable is attached to the guide. The opposite end is clamped in its position on the pinion by a riveted bracket. The cables run in metal tubes to the guides. As the sunroof panel is closed, the cables are pulled through the metal tubes. The displaced cable is guided into plastic tubes which protect the cable and prevent it snagging. The cables are made from rigid spring steel and therefore can push as well as pull the sunroof along the guides.
A sunshade is also located in the guides. When the sunroof panel is opened or tilted, the sunshade moves rearward. When the sunroof panel is opened, two brackets on the sunshade engage with the panel as it is retracted. The sunshade is then pulled back by the retracting panel. When the panel is closed, the sunshade remains retracted until pulled manually to its closed position.
Drain hoses are connected to the front and rear corners of the frame. The drain hoses are located inside the 'A' and 'D' post pillars to allow water which has collected in the frame to escape. A one-way valve is fitted to the end of each drain hose to prevent the ingress of dirt and moisture.
Servicing
Servicing is limited to adjusting the glass panel and replacing the drive unit. The drive unit is accessed by removing the access panel fitted to the forward interior light panel.
Scheme 15
The sunroof is operated by the three-way switch, via the Body Control Unit (BCU), with the following switch position options
- Rest position
- Open sliding/tilting sunroof (sliding open)
- Open by pressing and holding (one-touch function for sliding open)
- Raise sliding/tilting sunroof (tilting open)
- Close sliding/tilting sunroof (sliding shut/tilting shut)
- Close by over-pressing (one-touch function for sliding closed).
The drive is automatically shut down when the limit positions are reached. Limit position shutdown is initiated by the integral increment sensor isolating the motor. Limit position shutdown occurs even if the control remains actuated or is operated a further time in the direction of the limit position.
If a failure of the sunroof motor occurs, the sunroof can be closed manually. Access to the motor drive output shaft, in the roof access panel, enables the fitting of a special key which can be used to manually drive the sunroof to the closed position.
The sliding/tilting sunroof is operational with the ignition switch in position II for one-touch operation and position I for operating the control. In addition to the basic functional specifications, nationally specific specifications are configured via the encoding of the basic module. The necessary signals are transmitted via the P-Bus. If no signals are transmitted via the P-Bus, the functions remain limited to manual operation.
Note. The encoding functions are configured using T4
The following functions are available
Manual Operation
The desired sunroof position can be selected by operating the control in the open/tilt/close sliding/tilting sunroof positions. The control must be pressed permanently to do this.
One-touch Function
Pressing and holding the sunroof switch momentarily, for either the open or close selection, will enable the sliding/tilting sunroof to travel fully to the selected closed position. This selection can be interrupted by operating the switch a further time.
If the "tilting" control is operated while the panel position is within the "sliding open" range, the roof automatically moves to the limit position of tilting. This process can be interrupted by operating the control a further time.
The one-touch functions are encodable. This is a function of T4.
Anti-Trap Function
The anti-trap function, configured to meet the specific requirements of individual national regulations, operates by monitoring the torque output of the sliding/tilting sunroof drive. It operates when the sunroof is closing and the opening is greater than 4 mm. To ensure that the sunroof fully closes it is disabled for the last 4 mm of travel.
Note. The encoding functions are configured using T4
Operating during one-touch operation, actuation in the first switch position and during one-touch closing, the anti-trap function is disabled when emergency closing (panic mode) is selected.
After the anti-trap function has been activated the sunroof will return, depending on vehicle configuration, at maximum system speed, to the point at which the close selection was initially made.
Convenience Operation
The sunroof and windows can be fully closed or opened by holding the door key in either the locking or unlocking position, or with the remote control. Releasing the key before the operation is completed will stop the sunroof travelling.
The anti-trap function also operates when convenient closing is selected.
If the key is returned to the rest position, any convenience function that is currently in progress is terminated. If the control is operated during a convenience function, the convenience function that is currently in progress is terminated and must be restarted. Automatic resumption after the control is released is not permissible.
Consumer Shutdown
During the starting process (ignition position III), the sunroof is deactivated via the P-bus. The current selection, e.g. opening or one-touch functions, is immediately terminated and sunroof movement is halted.
If an undervoltage of less than 9.5 V occurs, the one-touch operation that is in progress will be terminated and no new sliding/tilting sunroof movement is initiated.
Sleep Mode
To reduce the current consumption of the vehicle, the sunroof control system switches to an electricity-saving mode after receiving the telegram "Go to Sleep" from the BCU via the P-Bus. In this condition manual operation of the sunroof will result in the loss of its absolute position. It will require re-initialising.
The electricity-saving mode is exited again by any telegram on the P-bus.
Fault Patterns
The following fault patterns are provided
- Overriding temporary shutdown (max. switch-on time 15 s)
- Shutdown of the drive in event of relay contacts sticking or faulty semiconductor after max. 500 ms
- Shutdown of the drive in event of no signal from the increment sensors after max. 300 ms
- Substitute function (e.g. motor stop) in event of implausible signals from sliding/tilting sunroof control and other faults (signal lines)
- Repeat interlock (by software, as substitute for motor thermo switch).
Diagnosis
The sunroof control unit has a built in test function to allow self-checking and self-diagnosis.
The exchange of information with the diagnostic unit takes place through the basic module via the P-bus. It can be used to identify three possible faults.
- Mechanical stiffness (fault in the sunroof unit)
- Implausible input signals (control fault)
- Electronic fault.
Initialization
Initializing the sunroof allows the control unit to learn the end positions of the motor's travel. The Hall sensors provide pulses for motor rotation, the control module counts the pulses and determines where the panel is by memorizing the stored pulses.
If the system is not initialized, the sunroof will only operate in the tilt up and slide close positions.
Initialization Procedure
Press and hold the sunroof switch in the tilt position for 20 seconds, to tilt the sunroof fully open and begin initialization. After the 20 seconds, momentarily release the sunroof switch, then press and hold it in the tilt position again until the sunroof has closed, then slid fully open and closed again (approximately 10 seconds)