My speedo was broken, so I managed to fix that, but now my tachometer goes up, then down, then the correct reading. I understand this is tell me there's a fault, and I guess it's a fault with the sensor as I've replaced the speed sensor and that's now working fine.
I've got a multimeter. What should I be testing and looking out for on the rev counter sensor?
Any help or link to info would be appreciated.