bouncing rev counter

[speedline]

hi,
i fitted a set of dials from a micra SLX with a rev counter, i spliced into the blue wire on the ignition pack to get a signal for it , as i dont think my ECU has a pin for the rpm signal, however when i start the engine , the rev counter is steady for about 2 second then jumps around erratically from 1,000rpm to 4,000rpm , anything obvious im doing wrong?
cheers

 

[martinb]

should just be plug and play mate? unwire the the spliced wire and try it, did u test the clocks previously on the slx or was it off a car in breaker/scrapyard?cheers and welcome although its says u joint 2008 but no posts?

 

[speedline]

hi, thanks for the reply, i bought the clocks from a scrapyard, and have no way of testing them, is there any where else i can get a signal from to test them. everything else worked straight off.
any help is very much appreciated.

 

[martinb]

i was told it should just plug and play, no splicing into wiring? maybe somone else could shed some light?