Odd one that I know is documented but I can't seem to find the fix link. TT speedo bangs over to 180km/hr on startup and then proceeds to run backwards towards zero when accelerating. Has to do with a couple of dry points on either the speedo board or rear of the speedo cluster needing to be resoldered. Don't want to buy another cluster as this one has correct kays and a full LED bulb replacement kit. Can anyone assist?
If you do have to buy an new speedometer, it should swap into your old cluster, so no need to worry about odometer. It's what I did when changing from 180km to 260km readout.
Sounds like a dry joint in the green electrical board on the back of the cluster, Mine was doing 120 when idling in the driveway, Changed this and it went back to working as normal.
Years ago, my Speedo was doing something similar. Cruising at a constant speed and it would jump around all over the place. Took it to a fella who I believe touched up all those solder joints and it was as good as new
If you do get another cluster to do the speedo unit swap, make sure you get the right series S1 & S2 have noticeable differences.
