Audi Instrument Cluster LCD Repair

| by Ken | in Automotive Add comments

For years now I have been losing rows of pixels from my 2001 Audi S4 instrument cluster LCD display.  At first, probably 8 years ago, I lost a row in the winter and then it came back in the spring.  Then it went away again in the winter and so on.  But then it seemed to be permanently gone with other rows coming and going, either depending on the weather or who knows what else.  But before my repair, I had numerous rows permanently dead.  Here’s what the LCD looked like before the repair (you can see something like 17 rows of pixels are dead):

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(Note that all images in this guide link to full size versions of the pictures in their own window.)

Actually, from my research I guess I’m not so bad off.  Many people had many more rows die and when their cars were much younger.  But still, mine has gotten bad enough that I can’t read the song title from the radio or the temperature outside.  So it’s time for a repair.

The challenge in this repair is that the LCD display is not an individual module intended to be replaced but merely a component on a circuit board.  And that circuit board contains smarts like the odometer reading and so forth which makes replacing the whole instrument cluster a real pain.  (Obviously, if it was easy to update the mileage, there’d be rampant abuse.)  In the end, it took a full day and it turned out to be one of the hardest repairs or hacks I’ve done.  Fortunately, there is some really good information out there but I got stuck in a couple of places so I thought I’d do my own write up with my own pictures to hopefully help out anyone else who is going to do this.

Okay, first of all, many thanks to S4_Raleigh and by extension, MacGyver, both from AudiZine.  S4_Raleigh wrote up the great post on the repair using info from MacGyver and that’s what my post here is based on.  In fact, I recommend you start by reading that post now (just the first in the thread) before continuing.

Next, before starting to pull apart your dashboard, read through this whole post.  You may well decide it isn’t for you.  And that doesn’t mean you aren’t smart – in fact, you may be smarter to just pay somebody to do the repair for you.  Especially if you can live without the car for the few days while the instrument cluster is sent away for repair.  There are services that specialize in this work and have relatively quick turnarounds.  But I couldn’t find a reliable review or rating for somebody that could turn it around quickly and I couldn’t find somebody near me that I could bring it to.  So I decided that I would rather not take a chance on sending it out and be without my car for a few days but you may decide the opposite.

Here’s a list of items you are going to need:

  • Torx T-20 screwdriver or bit or Phillips screwdriver depending on the car
  • Torx T-10 screwdriver or bit
  • snips or serious scissors
  • needle-nose pliers
  • a bendable plastic scrap sheet
  • lots of small screwdrivers or rigid plastic scraps to use as pry levers
  • blue painters tape
  • soldering iron (a good one, no Radio Shack “pencils” allowed here)
  • soldering flux (I used a flux pen)
  • magnifying glass with light (ideally one for soldering that can stand on its own)
  • desoldering braid (or some other smart cleaner)
  • metal shears and metal files

I recommend Chip Quik.  This was the first time I used it and I agree with the author of the original post that it’s the way to go.  The idea is that rather than using regular solder which firms up quickly, the Chip Quik (opposite of the name) firms up slowly which allows you more “open time” with the solder.  That’s not normally a good thing but as you’ll see below, it’s really important for removing the old LCD.  I got my lead-free Chip Quik from Amazon.

And of course, an important item is the LCD itself.  If you don’t already know, an LCD works by opening or closing cells with a light source behind it.  In the Audi instrument cluster, the backlight continues to work properly but the LCD stops open or closing cells on a row by row basis.  You want to make sure you get an exact replacement for the LCD.  From what I read, you can get cheaper LCD replacements that are brighter than the original display – that means that the cells allow too much of the backlight through.  You end up with an LCD that doesn’t match the rest of the car and is generally too bright.  So it’s important to get a good match and I was very pleased to find that on eBay.  But I bought the second to last one so if that listing has ended, you can search for the seller spitzgerald to see if he has a new listing – if he claims it is OEM, it is.

Okay, so by now you have your new LCD, the Chip Quik, and the various other items.  Here we go.

1.  Make a note of the steering wheel height.  You are going to drop the steering wheel using the tilt adjustment and if you are like me, you forgot you could even adjust the height of the wheel.  Sit in the driver’s seat and note the visibility through the steering wheel to the instrument cluster.  For example, you can see the top of the speedo just under the steering wheel arc.  That’s where you are going to want to put the steering wheel back to when you are finished.

2.  Remove the steering wheel bezel.  This part is pretty easy.  Adjust the steering wheel to the lowest position using the lever on the bottom of the steering wheel assembly.  Then pop off the bezel with your fingers.  It just pulls out straight.

3.  Tape a bendable plastic scrap to the top of the steering wheel assembly.  I used the bottom of a cheese stick tray that happened to be just about the same size as the top of the steering wheel assembly.  If you aren’t as lucky, cut some paperboard like a cereal box down to size.  Wrap the blue tape around two times.  I started without the plastic and scratched up the top of the steering wheel assembly almost immediately when removing the cluster.  I quickly found the plastic and taped it in place.  But I didn’t use enough tape and when I was testing later, the tape let go and the plastic sprung up and surprised the hell out of me.  I speak from experience on this step!

4.  Remove the instrument cluster from the dashboard.  Depending on the vintage and make/model of your car, your instrument cluster will either have Phillips screws or Torx.  My 2001 S4 had T-20 Torx screws but older cars apparently have Phillips screws here.  And then you need to pull the whole cluster assembly out with your fingers.  Pull on the bottom where the screws came out, then more on the left, then more on the right, etc. until you can get the left side far enough out to see behind it.  Peek behind the cluster and you’ll see three wire connectors.  The one closest to you is the one to start with since you can see what you are doing.  On each connector, there is a lever bar that you need to snap out of locked position and swing 90 degrees as you are pulling on the connector.  When you get it right, the lever bar will push the connector the rest of the way out and disconnect without too much effort.  Repeat that for the other two connectors.  The instrument cluster is now free but you need to twist and turn it just so for it to escape the confines of the cowl and then clear the steering wheel.  (As you are doing this, you’ll probably see the blue tape on the top of the steering wheel assembly get scraped up – that’s why you protected it in the prior step.)

5.  Open the instrument cluster.  Do this by first removing the two Torx T-10 screws on the back.  Then you’ll need to pop open all of the tabs at once.  You can use the scraps of rigid plastic to do that or I just used an assortment of small screwdrivers.  This step is one of the more typical procedures so any way you can get them all open at once, go for it.

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6.  Remove the dial pointers and the display disc, very carefully.  I put some blue tape on the disc right at the center dial and that let me use a small screwdriver to gently pry.  I read in other places that you should not use a screwdriver but I couldn’t get my fingers under it enough to pull.  Maybe some sort of plastic tool without sharp edges that is used for prying electronics apart would work.  Or in addition to the blue tape, maybe try some paperboard from your recycle bin.  For me, a dull worn screwdriver worked well but just be careful since there’s no undenting a disc if it is bent.  Set the pointer aside in a location that you’ll remember which pointer goes to which dial.  You will need to remove 4 pointers: the coolant temperature (“C” to “H”), the gasoline, the tachometer, and the speedometer.  (Do not remove the pointers on the oil temperature or on the battery gauges – they will not be removed.)  With the 4 pointers removed, you can now lift the tab and turn the tachometer disc and you can simply turn the speedometer disc – both will come off once they have been turned so the holes near the center align with the tabs on the center post.

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7.  Remove the main gauge frame.  First, you’ll need to snip the white plastic loop connecting the main gauge frame to the oil temp and battery gauges.  The loops look like upside down Omegas (if that helps).  Snip it anywhere on the curved part.  I used some serious scissors but angled snips would work too.  Also snip the small connection between the main gauge frame and the two digit readout blocks (where the time and date show up on one side and the trip and odometer show up on the other).  It’s a small white connector piece near the center of the dial and in the center of the digit readout block.  I was a little hesitant to snip these parts but after I did it, I realized there really was no harm in doing it.  Then you can turn the board over and push the tabs to release the plastic frame.  You will also need to push the plastic part from the right side peg through the back to release the white gauge frame.  (In the pictures, I hadn’t clipped the connector to the clock and odometer displays and had removed them but I later read that I hadn’t need to do that so I clipped the connector later and put the clock and odometer blocks back in but don’t have pictures to show of that.)

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8.  Remove the metal frame holding the LCD over the backlight.  Turn the board over to the back and using needle-nose pliers, bend the four tabs of the metal cage enough that they can push through the board.  Use caution here because you are now getting into sensitive areas and don’t want to manhandle anything.  Once the cage has been removed, you’ll see that you can now lift up the LCD panel off of the backlight.  Keep track of all the parts here.  On mine, I had two rubbery strips under the LCD panel and one of them stuck to the backlight assembly while the other stuck to the LCD panel so I had to remove it from the panel and put it on the backlight.  I was careful to keep the orientation the same, just in case that mattered.

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9.  Now the first hard part – time to remove the old LCD.  (That’s right; up until now, this has been easy.)  Follow the Chip Quik instructions.  I think I started with the flux pen, though I can’t remember for sure.  Melt some Chip Quik across the tiny traces on the LCD as though you were doing a really sloppy job of soldering – the Chip Quik will end up as sort of one long bead across all the traces.  After you have some there (not too much, but enough – you’ll know), run the iron back and forth over the Chip Quik to keep it warm and as you are doing this, apply slight upward pressure to the LCD ribbon.  At some point, it will come off the board.  (I forgot to take a picture here, sorry.)  There is a gray rubber strip running down each side of the backlight assembly.  When I first removed the LCD, one of the rubber strips stuck to the LCD so I had to remove it from that and put it back in the right place on the backlight assembly.  I made sure to keep the correct orientation in case it made a difference.  (I don’t think it did.)

10.  The next hard part – cleaning the board.  The idea is that you run the iron over the Chip Quik that remains to keep it warm and then scoop it up with something.  The Chip Quik instructions say to use a swab.  The only swabs I have are for my ears and they left some cotton bits behind so I’m sure there’s something better out there for this job.  I also had trouble when a Chip Quik blob ran away on me and lodged itself on some other connectors.  At this point, I got out my desoldering braid and sucked up the errant blob and made sure that the connectors it visited were now well soldered.  Then I returned my attention to the LCD trace area and cleaned that up with the desoldering braid.  I kept repeating the process until the area looked clean of solder then I used the alcohol pad provided by Chip Quik to clean up the residue left behind.

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11.  Another hard part – tin the traces.  You need to melt a small portion of solder on to the traces – remember you just cleaned up solder that was there so now you need to replace what you removed to accept the new LCD ribbon.  Ideally, you want to lay down a small and equal amount on every trace.  This is where you get to test your eyes.  Even with the lighted magnifying glass, my eyes had a hard time keeping track of where I was.  I got into a rhythm by probably the 4th or 5th to last one – figures.

12.  The hardest part – solder the new LCD.  Why is this hard?  Because there are so many freaking little things to solder.  Flux the newly tinned traces on the board.  Put the ribbon of the new LCD down over the traces on the board.  Pay extremely close attention to make sure that everything is lined up perfectly.  I found that the stickiness of the flux helped the ribbon from moving too much but I still had to keep an eye on it.  Then I started applying heat to the top of the ribbon.  When that area cooled, it meant part of the ribbon was anchored so I could stop stressing about the ribbon moving.  Then I could move on to each trace, one by one.  I went quickly so I didn’t damage any of the traces.

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I’m going to interrupt the instructions here to let you know that I had a problem here that I didn’t realize until I had reassembled everything.  Even though it looked like the traces were all nicely soldered, they weren’t.  I had a few apparently that were missed because the display wasn’t lighting up correctly.  So I suggest that you very gingerly test the instrument cluster in its current state.  You will want to hold the LCD over the backlight to protect it (perhaps even use some blue tape to hold it in place).  The LCD should still have its protective plastic sheet over it – don’t remove that yet.  Definitely do not – I repeat: do not! use the LCD cage at this point.  It may seem like a good idea but it is definitely not.  You should be able to carefully get the instrument cluster in the car and hook it up to the three connectors.  You will need to actually move the levers on the connectors to get them to engage the contacts though you don’t need to go as far as locking them in place.  Turn the car on and check to see how the display looks.  At this point, if you got the soldering right, it should look perfect.  If you got it wrong, odds are good that the display will be pretty messed up – more than just missing rows – so try moving your finger (not fingernail) over the traces and see if you can improve the display by doing that.  When you find an area that looks like it improves things, you can take the display back to the soldering iron and work on that area.  I repeated this cycle 5 times before I got the soldering done well.

13.  Not hard but critical part – alter the LCD cage and then reattach it.  The LCD cage is, I think, the key problem with the original LCD failing.  It has a piece right in the middle that bends inward toward the display.  Presumably, this is to hold things in place.  But I discovered that when I put my cage back on without modification, it created a crease in the brand new LCD ribbon.  And that crease appeared to directly correlate to a new row of dead pixels in my brand new display.  Much profanity ensued.  Removing the cage and reattaching it appeared to create another row of dead pixels.  More profanity.  It was at this point that I realized what was at fault and realized I couldn’t use the LCD cage in its current form.  It is still necessary to hold the LCD panel in place but I don’t see any reason why it has to clamp down on the ribbon so tightly.  So using metal shears I cut out the whole side of it where the ribbon cable passes through.  Then I filed the hell out of it to make sure there wasn’t a sharp edge anywhere near the ribbon cable.  This took a while but was totally worth the effort.  It’s possible that simply bending the cage’s small tab away from where the ribbon will go would be enough but since it had already done damage, I didn’t want to risk any more.  You can choose how big a modification you want to make initially – either just bending the tab or cutting away the side.  However, I strongly recommend you do at least the tab modification.  After pushing the cage back into place, I suggest you confirm that the display is working well as I described above.  And when you are ready to commit to reassembly, bend the tabs on the back of the cage to hold it in place.  (The first picture below shows the way that you would bend the tab.  The second picture shows my cage after I modified it – note the whole side is gone except for a little near the top and bottom that seemed to be out of the way of the ribbon enough.)

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Pausing again from the instructions: So what did I do about the fact that my new ribbon cable was already damaged?  The profanity didn’t fix anything.  I played around with the ribbon cable while it was connected and noticed that I could get both pixel rows back if I moved the cable around.  I figured out what position would work best and I rolled up some blue tape into a sort of squishy stick and placed that under the ribbon.  That held the ribbon in the right place even when the cage was reattached.  And thus, all rows in the display now work.

(If you are like me, you are probably thinking that it would have been interesting to skip the whole effort of replacing the display and just try removing the cage and moving the ribbon around to see if you could get all the rows back.  I thought about suggesting that at the outset of this guide.  My guess is that the years of the pixel rows not working is confirmation that it is more than just a ribbon wiggle.  But if you are reading this thinking that you could try that before spending the money on a new LCD display, give it a shot and see what happens.  And let me know!)

14.  Reassemble the instrument cluster.  Basically, you will now reverse the procedure for disassembly.  Start by putting the white plastic gauge frame back on the board.  (Note to be careful where it gets close to the LCD ribbon.)  Then replace the gauge discs by fitting them over the spindle and turning appropriately.  Now put the pointers back on the same spindles they were on originally.  You want to simply push them on the spindles but be sure to push them on straight with even pressure and do not push them too far down.  You can use the pointers that you did not remove as a guide for how far down to push them.  Note that there is no indexing for the pointers so you could theoretically aim the pointer any way you want and end up with wildly inaccurate readings.  But all of the dials appear to have positive zero stops that you can use to align the pointers.  So I made an effort to not spin the spindles while the needles were off and therefore when I put the pointers back on, they were in the general ballpark of being correct.  I then turned the pointer gently counter clockwise until I hit the zero stop.  If I went to far, I turned the pointer all the way in the other direction and deliberately turned it too far, then I could turn back again the first way to reset it back to zero.  I did find a couple of dials were a little off when I powered up the instrument cluster for a test so I disconnected and adjusted.  When the dials are good, reattach the cover by pressing it through all the tabs and screw back in the two Torx screws on the back.

15.  Put the dashboard back together.  Finally an easy part.  Just push the connectors in as you probably already did for testing.  This time, make sure each of the connector’s lever locks fully into place when the connector is fully inserted.  I noticed that I needed to press extra hard on the connector furthest to the left to make sure the clock and date LCD lit up brightly – that’s weird.  Press the instrument cluster all the way back into place with your fingers and then screw back in the two screws at the bottom.  Replace the steering wheel bezel by hooking in the tab on either side and pivoting it back toward the instrument cluster.  When you do it right, you’ll hear little “pings” as it snaps into place.  Finally, raise the steering wheel back to the original driving height.

16. Success.  Power it up and get yourself an adult beverage – you’ve earned it.  And as you are enjoying the beverage, leave a comment and let me know if this guide helped you.

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