Instruments - Cluster Lighting Appears To Flicker
90 Illumination of dash insert flickers or is too dark when ambient light changes
90 11 26
2019950/4
July 13, 2011
Supersedes Technical Service Bulletin Group 90 number 10 - 10 dated July 7, 2010 for reasons listed below.
Affected Vehicles
90
Condition
^ In low ambient light (e.g. when driving through a tunnel or in misty weather), the gauges in the instrument cluster will dim to dark. However, the
needles for all gauges, center screen, mileage/trip and time/date remain illuminated. When driving in areas of changing light (e.g. tree-lined
street), this is also described as flickering.
^ Beginning with 2010 models this will occur only when the headlight switch is in the OFF position.
^ For 2009 and earlier models this will occur only when the headlight switch is in the OFF or AUTO positions.
^ If the headlights are switched ON, the gauges are illuminated and the brightness can be adjusted over a wide range using the dimming wheel.
Technical Background
This is a design feature of the vehicle. High cluster illumination in high ambient light ensures gauge readability. Low cluster illumination in low
ambient light signals the driver that the headlights are turned OFF. The intent of this feature is to remind the driver to switch ON the headlights when
driving in decreasing daylight.
The illumination is controlled by a photo sensor. On the A3, TT and R8, the sensor is installed in the speedometer below the scale imprint of the top
speed (circular surface with a diameter of about 5 mm). On the A8, the sensor is centered below the driver information system.
Production Solution
Service
1. Explain the design feature to the customer. If customer prefers, follow subsequent steps to illuminate the gauges at all times.
Tip: After changing the code in the dash insert, it can no longer be determined whether the vehicle light is switched on. Please ask the customer to
switch the vehicle light on early in low-light conditions.
2. Check the function of the photo sensor by covering it by hand or shining light on it. The illumination should become darker when covering it and
brighter when exposing it to light.
3. If the photo sensor works, the instrument cluster code can be changed to permanent night operation. Change the last digit of code in the instrument
cluster (address word 17) according to the following table:
Warranty
This TSB is informational only and not applicable to any Audi warranty.
Additional Information
91
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service
manuals for the latest information.
