Tail Lamp: Description and Operation
9431 - Rear Lights
Particular attention has also been paid to the new night time design of the Boxster/S (987) when it comes to the rear view. The tail light, which always featured a very simple design on previous Boxster/S (986) models, now lights up three tail light chambers to create a new characteristic Porsche night time look at the rear, as well. The bulbs in the rear lights are produced in long life quality.
The third brake light is a new development in LED technology and is integrated into the styling of the Boxster's rear section. A striking feature is the light's silver grey cover panel, which lends the vehicle's rear an even more powerful appearance.
The new LED technology has a number of clear advantages in terms of service life and response time. The response time of bulbs is around 100 ms. By comparison, LEDs respond after around 0.1 ms. This difference translates to a distance of almost 10 ft (3 m) at a speed of 62 mph (100 km/h). Earlier indication of an intention to brake means more time for other drivers to react. LEDs also have a considerably longer service life (generally in excess of 10,000 hours) than conventional bulbs that need to be replaced after only 200-1000 hours.
Brake Light Switch
The PSM control unit identifies a brake light request from the redundant switch combination consisting of "brake light switch" (BLS) and "brake test switch" (BTS). The PSM control unit also checks the sequence of opening/closing operations performed by these switches for plausibility.
The brake test switch must open first when actuated, following which the brake light switch must close after a short delay.
NOTE: The left brake light is activated directly via the brake light switch. The rear control unit activates the brake light on the right and the 3rd brake light.
The PSM control unit relays this information via CAN Drive and passes on the messages to the Motronic control unit. In parallel with the PSM control unit, the rear control unit and the driving authorization control unit (Porsche Access System - PAS) read in the signal from the brake light switch.
Light Failure Monitoring
Most exterior lights are equipped with a failure checking facility. In the event of a problem (e.g. bulb failure, wire defect), a corresponding message is displayed in the instrument cluster.
The following lights are monitored:
- Dipped beam
- High beam
- Marker light
- Indicator light
- Brake light
- Rear fog light
- Backup light
In case of light failure during "ignition off", the fault is stored and subsequently transmitted via CAN in conjunction with the next "ignition on" cycle. The light failure checking facility is not active during "sleep" mode. In case of light failure during "ignition on", the fault is transmitted directly.