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After many years you may have found that your MMI display screen is really dull and barely visible in daylight. This is caused by ageing of the CCFL (cold cathode fluorescent lamp) tube which is used as the backlight for the display and fades in brightness after several years.
The solution is simple. Just fit a new inexpensive CCFL tube lamp into the display. It is not a difficult task and removal and fitting takes about 10 minutes each.

The procedure described below was for my 2009 Audi A5 3.0 TDI, but will apply to many other models in same era.

The panel is backlit with a CCFL tube which is U shaped (so illuminates from top edge and from both sides). These U shaped tubes are difficult to source. However an L shaped tube works fine. Illuminates from top edge and only one side. There is barely any difference in end result and uniformity of illumination. I fitted a 130mm x 80mm x 2.0 thick L shaped tube lamp which I purchased for £9 plus £5 postage from a (very helpful) Polish seller on ebay UK. This produces a very uniform illumination. The maximum size of the L shaped tube (including end connectors) can be up to 149mm x 89mm x 2.6mm thickness

Turn off ignition. Battery does NOT need to be disconnected.

1. Remove the decorative dash trim piece surrounding the screen.
This just pulls off. You need to try to grip it with both hands, especially the left side. The bottom efge comes off first. Use friction with all your fingers on the upfacing area just to the right of hazard switch. It will start to pull off. You can very carefully insert a plastic blade to ease up the bottom but should not be needed.
Once off, leave the hazard light switch cable connected and swing the decorative panel over into the top of dash out of the way.
You now see the display screen mounted onto a metal chassis.

2. Undo the 4 torx screws screws (one at each corner) and release the panel assemble. Take care not to drop them doen into dash area! Release the cable loom plug at the rear, and remove the panel assembly from the vehicle. Take it somewhere where you can work safely on it.

3. Undo 4 screws (one each corner) on the metal framing surround, and carefully lift off the metal surround.

4. Now you need to split open the panel. This is very easy. Fold back 4 tabs on the shiny metal edging that are wrapped or folded around the sides. 2 tabs fold upwards and 2 tabs fold sideways. One each, on each side.
As it begin to fold opn you will see a white plug on top edge of power supply pcb, with two wires (one white, one pink) coming from this plug. These wires go to the ends of the fluorescent tube. PULL OUT the plug from the pcb socket. Access is a bit awkward so use a small screwdriver to ease up the plug. Once released you can now fold open the screen, which will be hinged on a gold ribbon cable.

You will see a U shaped 2.6mm fluorescent tube that is laid around three sides. With connexting wire at each end of the tube.

Remove the old U shaped tube.

Lay in a new L shaped tube.

You will need to carefully cut the wires of the new tube to attach the old plug onto new tube. I found that the new wires were much thinner than original wires and would not stay locked into those cable-clips on the black plastic, so i also retained about 6 cm of the old wire which being thicker would stick tight into the holding clips.

ASsembly is now the reverse process

Carefully fold together the screen panel. This is best done whilst holding hinged panel vertically otherwise the various sheets of plastic and the clear perspex bezel will keep falling out. Take care that the new tube is well seated and clear around perimeter. For thecwire connections onto tube, I used the new plastic end connctors that came with my new tube and a few cm of the new wire. HOwever i did clip a little of the plastic plug off, to reduce end connector size and avoid fouling the perimter.

At the final stage of folding shut the screen, refit the white power plug onto pcb.

Once screen folded shut. Fold back the 4 metal tabs to hold it all together. Dont worry if it feels a bit loose. It is also held together by the next steps.

Refit the metal surround frame with the 4 small philips screws.

Clean the display face.

Mount display back in the car dashboard, IE. first re-attach the connector cable,into back of panel, then mount panel onto the metal,chassis and refit the 4 torx scews to hold it in place. Take great care NOT to drop these screws down into the depths of the dash inner area. A nightmare to recover.

Test that it works.

Refit the decorative panel which is a simple pushfit... top goes in a bit before the bottom.



4,580 Posts
Nice write up. Well done.

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792 Posts
Good stuff, thanks for sharing this!

1 Posts
Hey, I can’t seem to find the right CCFL fluorescent tube online. Could someone send me the link where I can purchase one??
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