Tachometer Problem

Post by **Kevin** » Wed May 12, 2004 8:17 am

I have a friend who is trying to fit a Tim Tacho (second hand no instructions) and he is having problems with it, it reads OK up to 3000 rpm and then the needle drops back to zero and then becomes erratic, does anyone have any ideas or even a copy of a wiring diagram, if it helps the car is -ve earth with an alternator.

Post by **Matt** » Wed May 12, 2004 11:28 am

how many wires come off the back, and what colours are they? I know most tachos run by picking up the current running from the coil (or somewhere similar)

Post by **Kevin** » Wed May 12, 2004 1:48 pm

I will have to find out as I have not a clue

Post by **racer** » Wed May 12, 2004 1:50 pm

I have a pod mounted TIM tacho . Heres how mine is wired .....BLACK to earth/WHITE to power for illumination of dial / RED&GREEN to pos.&neg of coil (swap green and red over if tacho not functioning) I have neg. earth system .Hope this helps!

Post by **Kevin** » Wed May 12, 2004 1:55 pm

Thanks Racer I will pass the info on.

Post by **Wal** » Sun May 16, 2004 12:37 pm

Hi,
two things you might want to check - is the tacho is set for the right number of cylinders? I have a tacho (though not a TIM item) on my car and it has a switch on the back that allows you to change the cylinder settings 4,6 or 8. I had this set wrongly and got lots of funny readings before I realised. The other main culprit for odd readings is the earth, make sure it is earthing properly otherwise you will get funnies, also learnt from experience.

Regards,
Wal

Post by **racer** » Sun May 16, 2004 5:50 pm

Thats a good point ,didn't think of that one !!

Post by **turbominor** » Thu May 20, 2004 3:09 pm

also measure the voltage over the engines rev range at tacho's are very senstive to voltage problems.

My last moggie the regulator started to fail, first thing i noticed was the revcounter playing up..