10 replies to this topic

[Mininman_Aid]

Hi guys

I've bought one of these 52mm after market rev counter tachos and i've tried wiring it up as per the instructions that came with it (one wire to switched live, one signal and one grounded) and also to the original wires for a 3 clock dash... and i dont get anything happen on the tacho.

I've tried a Mini tacho out of my other Mini and it works fine on the same wires... and i've now tried 2 of these new after market tachos... and idea whats wrong?? Are they just not compatible??

Cheers All.


Aid

[megla_mini]

Hi, where are you taking the signal from, the coil?

[Mininman_Aid]

Hi, where are you taking the signal from, the coil?

i've tried both sides of the coil and from the connection at the side of the distributor... where the points connection is i believe.

[Joef]

Is it set to the right amount of cylinders? It should be on the negative side of the coil by the way. Maybe you've buggered it by wiring it incorrectly? Just a thought...

Ive got a racespeed one off ebay in my mini and it works fine. Came set to 6 cylinders though, there was a switch on the back to change it..

Edited by Joef, 05 February 2008 - 08:37 PM.

[Mininman_Aid]

Is it set to the right amount of cylinders? It should be on the negative side of the coil by the way. Maybe you've buggered it by wiring it incorrectly? Just a thought...

Ive got a racespeed one off ebay in my mini and it works fine. Came set to 6 cylinders though, there was a switch on the back to change it..

where does the original mini wire connect to? i've tried connecting it to negative and nothing... and its set to 4... checked that first!

[Mininman_Aid]

is there a way to test the tacho??

[megla_mini]

Is it set to the right amount of cylinders? It should be on the negative side of the coil by the way. Maybe you've buggered it by wiring it incorrectly? Just a thought...

Ive got a racespeed one off ebay in my mini and it works fine. Came set to 6 cylinders though, there was a switch on the back to change it..

where does the original mini wire connect to? i've tried connecting it to negative and nothing... and its set to 4... checked that first!

The original mini wire which is black and white connects to the negative side of the coil. are you sure you have a good earth connection. this caused me problem at first but once earthed properly worked fine.

[dklawson]

This isn't one of the "2 GBP" eBay tachs from China/Hong Kong with "20 GBP" shipping is it?

The normal color codes for the aftermarket tachs are "black = earth/ground", "red = switched 12V", "green = sense = coil (-)", and "white = illumination/lamp".

Without test equipment such as a signal generator it's not easy to test a tachometer. You could hook up its power using temporary leads and then rapidly tap the green wire to a 12V supply to see if you can get the needle (or display) to show something. However, 600 RPM is 20Hz (for a 4-cylinder tach) so you'd have to tap rather quickly to make anything happen.

[Mininman_Aid]

This isn't one of the "2 GBP" eBay tachs from China/Hong Kong with "20 GBP" shipping is it?

The normal color codes for the aftermarket tachs are "black = earth/ground", "red = switched 12V", "green = sense = coil (-)", and "white = illumination/lamp".

Without test equipment such as a signal generator it's not easy to test a tachometer. You could hook up its power using temporary leads and then rapidly tap the green wire to a 12V supply to see if you can get the needle (or display) to show something. However, 600 RPM is 20Hz (for a 4-cylinder tach) so you'd have to tap rather quickly to make anything happen.

I've made it work now, for some reason it wont run off the mini's wiring loom, so i've run another wire from the coil to the tacho, from the negative side, found a good earth and good switched live and it started working. the first tacho i had only blips up once, seems like it only picks up one pulse or something... i dont know... i'm a mechanical engineer not an electrical one!!

and no its not a cheapie one its an Auto gauges one. I've used a few other of their guages and they've been good... hence why i tried this one!!

i just need to go back and wire it in perminantly when i get time!!

[dklawson]

Hey "we" M.E.s can do a LOT of automotive electronics... until the computer controls start getting involved. You don't have to be an E.E. for a lot of this stuff.

I'm glad you got it sorted out. The first tach may have been detecting a power pulse on the 12V supply that caused it to blip. The obvious things I'd check were I you are that the first wiring points you tried had a good earth/ground and that you had 12V power when you thought you did. After that, check for continuity between the black/white wire you found under the dash and the one on the coil. It might be that there is a dis-connected connection somewhere along the black/white wire.

Edited by dklawson, 05 February 2008 - 09:30 PM.

[Mininman_Aid]

Hey "we" M.E.s can do a LOT of automotive electronics... until the computer controls start getting involved. You don't have to be an E.E. for a lot of this stuff.

I'm glad you got it sorted out. The first tach may have been detecting a power pulse on the 12V supply that caused it to blip. The obvious things I'd check were I you are that the first wiring points you tried had a good earth/ground and that you had 12V power when you thought you did. After that, check for continuity between the black/white wire you found under the dash and the one on the coil. It might be that there is a dis-connected connection somewhere along the black/white wire.

he he, well i'm actually quite good with electronics. if it wasnt for all that signals maths nonsence i'd have been more interested in electrical engineering...

yeah i've tested the black/white wire and it doesnt seem to be connected to the negative of the coil at all... even though it still powers a standard tacho!

Ah well, its all working now!! I'll send back the one that doesnt work and see if they say anything about why it doesnt work!