I have a 1997 civic EK hatch with a JDM GSR in it. When I purchased a vehicle it was already swapped it was an automatic car converted to a five speed. They did convert the gauge cluster to manual although the RPMs was off about 90% of the time. To fix this issue I went and bought a used civic SI gauge cluster (that way the RPMs would match the b18c) although when I plug it in the mph starts at 20mph. It does move consistently 20 over everything even 0 mph and the temp gauge goes straight to hot. Any help would be great thanks?

 

Try using the Green electrical film from the EK cluster on the SI cluster your using.

 

I did try swapping the green film as well as I even swapped the speedometer I’m guessing there is either something wrong with my wiring to my RPM gauge because now my RPM is working fine but my speedo is not. Tomorrow I will try to put the guts of my old RPM back in and see if my speedometer works and my RPM goes back to not working.
I have also seen a lot of people on YouTube saying that the cold Solder goes bad on the back of the boards I can try to heat that up and re-solder tomorrow as well.