Tacho Showing Over 9000?!

[Kinks]

My tacho one day decided to go crazy, when idling it was sitting around 4000RPM and as soon as I drove off it would bounce around between 7000 and 9000RPM. Tapping the dash behind the steering wheel made the needle fluctuate so it was clear something wasn't right in the instrument cluster. Plugs were all in firmly so the cluster itself was the next suspect. Since I managed to fix it here's what I did:

Start with cluster out (there are plenty of other guides to get to this point):

Around the edge of the cluster you need to unclip the plastic clips (arrows) - there are a bunch of them top and bottom of the cluster, work slowly and gradually unclip them all and the front will pop off. Careful about the reset needle for the trip meter, if you are agro with it you will damage it. Be gentle once you've got the clips undone!!

You should now have a naked instrument cluster (oooh baby!)

Flip it over and undo these 6 screws, careful as when you undo the last one the tacho will fall out.

You should now have a naked tacho module (I'm excited)

Here's a suspect capacitor, looks like it's had better days. It looked suspect, so I changed it. If you change it with the same value you shouldn't have to touch the adjustment pot (right next door). If you do need to recalibrate your tacho this trimpot will let you.

Replace the capacitor with the same value of 15nF (replacement is marked 2A153J - the 153 means 15 with 3 zeros, in picofarads. 15000pF = 15nF). Adjustment potentiometer highlighted in case your tacho is now off - mine wasn't so I didn't have to touch the trimpot (I did anyway, but that's because it was there and I wanted to play with it).

Put it all back in reverse order and your tacho will be less crazy*. I took a photo of 9000RPM for posterity, I hope my RB never actually hits this since it would not end terribly well

(*statement is true if you have made the necessary prior sacrifices to the skyline gods. I take no responsibility for cack-handed, ham-fisted or butter-finger moves. If you end up in the emergency ward with burns from your soldering iron please tell me which ward you are in so I can point and laugh)