Instrument Cluster Backlight

[dherrick]

I have a 996 TT with an instrument cluster that does not backlight without the lights on.  The cluster backlights fine and dims with the headlights on but the cluster does not illuminate when the lights are off.  According to the Owners manual, the gauges are supposed to back light based on the ambient light sensor located in the tach near the 8k rpm indicator.  Since the instrument back lights do work with the lights on that is guiding me towards the light sensor.  Does anyone have any experience with this issue and were you able to repair it?

[alex222]

The ambient light sensor adjusts the brightness for the 3 displays on the instrument cluster. It's not the feature of "automatic lights" that been developed to the later models. The sensor is not switching the instrument cluster illumination ON or OFF when you are passing a dark spot or when it is getting dark. Those are with the "A- [lights symbol] feature. The illumination for 996/986 is switched on/off only by light switch knob. With the parking lights and instrument cluster illumination on, the ambient sensor adjusts the 3 panels brighter or darker as the it is lighter/darker in the cabin to the setting set by the adjustment knob. It does not adjust the instrument cluster back-light illumination. 

 

You can point your flash light from the smartphone on and off the ambient sensor while not driving with the engine on with the parking lights on and off and you see how the brightness changes on the 3 displays.

 

Edited January 29 by alex222