Thread: Surf rev counter issue

Not sure if anyone has come across this, my surf (1kz) has got an intermittent issue with the rev counter, seems to be worst in cold weather it reads far too low then eventually jumps to where it's meant to. I don't even know how a rev counter on a diesel works to be honest as they don't run the spark system of a petrol, one of you Toyota experts must be able to tell me where to start looking...
It did it last winter too but the ignore it and it will go away worked and it fixed itself, I shod be more proactive this time though....