Well, it seems that my Polo GTi has had some bodgers at it . I was beginning to suspect this because of the damage to the plastic binnacle where two of the three screw holes had been broken, a missing screw from the back of the instruments, the number of previous owners and the long list of error codes that were stored on the ECU that have never been sorted out..

I'll post some more pictures and a bit of a how to for other readers later, but I have managed to dismantle the clocks and get to the circuit board.

There seem to be two issues. Firstly there was a piece of black tape over the ABS led itself. Secondly, the mask that sits on top of the speedo seems to have the ABS section etched, but remains almost opaque. I took a photo at the window to show how it looks with daylight onto a white background. It does look as though a black square has been placed over the ABS area

|s it possible that this is from a lower spec car which doesn't have ABS or is it some sort of manufacturing defect ?

I fitted the board back in the car and the ABS LED lit and extinguished as it should. I then fitted the mask and the same problem of a dark ABS light remained. Unfortunately the airbag LED no longer illuminates, I believe due to me testing it with a 12v feed, it did illuminate but I suspect I have blown it. Looks like I'll have to source and fit an LED after all. One of life's lessons !

Edited 29 June, 201412 yr by 937carrera

Here's a quick guide on how to dismantle the clocks

1. Remove the instrument binnacle by using a Torx 15 screwdriver to remove the single screw

2. Pull the instrument binnacle forward to separate the shiny trim and outer from the matt inner section

3. Remove the 3 Torx 15 screws retaining the matt inner part of the binnacle, levering the plastic towards you to remove from the car. Be aware that there is a finger retaining the section just under the analogue clock

4. Remove the two Torx 15 screws to release the instruments and release the blue and green connectors to remove the clocks from the car

5. Turn the instruments over, it should look like this after removing the 7 torx 10 screws

6 Remove the white plastic cover and the rear of the circuit board is exposed

7. Turn the instruments over and you can remove the front faces, leaving the instruments exposed

8. Next remove the speedo and tacho needles. I used a two small screwdrivers and levered them up by applying pressure between the bottom of the needle centre and the instrument face. There's more force required than you might think. I also used some toilet paper to protect the faces from scratching, you should have something like this.

9. The next bit is more tricky. You have to remove the black masks from the dials. The speedo was a little easier so I suggest you tackle that one first. It is retained in place by clips onto the back of the plastic frame, which are accessible once you have removed the masks !. I managed it by using a finger nail to lever the base of the mask up and then inserted some matchsticks to maintain the pressure as i worked my way round. You should have something like this.

10 Do the same to the tacho which will now allow you to see the needles for the fuel and temperature gauges.

11. These have to be levered up using two small screwdrivers in a similar way to the large instruments.

12. When you have done that the plastic graphics can be removed and to complete dissassembly press on the 4 clips that retain the LCD's in place to release them. Be careful not to drop them. You should now have access to the naked circuit board.

Re-assembly is the reverse of the above. I found that it was best to assemble the circuit board without needles, trial fit into the car, switch ignition on (protect the board from unwanted live or earth connections). This seems to "zero" the large gauges, so you can then simply put the small needles on and move to the "off" positions then place the large needles in the zero position

The LED's themselves are of a surface mounted PLCC-2 3528 design, and they run on 2-3 volts, so I suggest any testing is done with a 1.5v battery. Remember, these are diodes so current only flows one way and polarity has to be correct for them to function. If you look very carefully there is a cutout which I believe indicates the negative side, if you are replacing just make sure they get fitted the same way round

I found the foillowing thread very useful in getting more background about what to do. http://www.saxperience.com/forum/showthread.php?t=73370

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Hope that helps someone

Time to wrap this thread up.

I bought some Osram LYT676-R1S2-26 yellow PLCC-2 SMD LED's (that's a long part number).

Specification wise these are wavelength 587nm, luminous intensity 280 mcd, they measure around 3.5mm x 2.8mm.

I used a pair of tweezers to hold onto the old LED as I de-soldered it from the PCB using a fine tip soldering iron, taking car to note where the polarity mark was situated.

I then took the new LED, turned it over and applied a small blob of solder, then using tweezers again placed the LED on the board and soldered it in position.

I also used solvent to remove the blacked out area over the ABS etching so that was as transparent as the other warning shapes.

It worked and both the colour and brightness was a perfect match

Job sorted. I learnt a lot along the way to correcting someone else's bodge job, many thanks for all the contributions

Glad you have it fixed. Are you gonna change the dial led colours? I'm thinking of doing this.

My focus at this point is very much to get rid of the various niggling issues with the car so that there are no stored error codes so I'm not doing anything that's going to distract my attention from that.

If you have a bit of experience with PCB soldering and the right gear, changing the LED's will probably not be too difficult, though it will take time. I was happy that the one I attempted worked so was happy to take that as a win.

This weekends remaining challenges are diagnosing the aircon problem (see my other thread) and fitting a new rear lambda sensor. Fitting the lambda sensor will be easy, removing the old one will be the hard part