Tachometer- what am I doing wrong?

[mike202]

I have a Smiths Tachometer from JK and I have wired it in correctly I believe:
Green to switched 12v from dash pod black wire supply with a 2 amp inline fuse ( I don’t have a 3 amp fuse)

Red/white to sidelight supply

Black to earth on the back of the dash pod, the bottom earth connection below the warning lamps / fuel gauge

Signal wire from -ve side of coil to the red/ blue wire.

The tachometer light comes on when side lights are on. When I turn the ignition on there is the slightest flicker of the tachometer needle. Then when I start the engine nothing!

I have tested all the connections by unclipping the tachometer loom connector and using my 12 volt tester light and there is definitely a signal coming through from the coil.

I even took off the rubber grommet at the back to check the switch settings and as far as I know this is correct 1 , 2 and 8 on and the other off.

I rang the tech help line for Smiths on the instructions but they had finished for the weekend.

This is the second tachometer as I had the same with the last one and I returned it. I can’t believe another one is defective what I am getting wrong !? [emoji37][emoji36]

 

[yoda]

Had similar experiences try swapping the wires round.thought I had the wires the right way round but when I turned the side lights on the rev counter switched off.

 

[mike202]

Had similar experiences try swapping the wires round.thought I had the wires the right way round but when I turned the side lights on the rev counter switched off.

Thanks for the suggestion but I would be a bit wary of doing that in case of causing damage.

 

[atafonso]

Mike normally the green wire is the one that goes to the negative on the coil, maybe double check if that’s not the case on your tacho

Abel

 

[mike202]

Thanks Abel, but the instructions say green to switched 12 volt.
I will just have wait until I can phone them up. [emoji12]

 

[atafonso]

Have you tried using the white/ black wire for the signal? Try it, i think it will work

Abel

 

[Foz]

Any resolve to this? I have fitted the same Tacho. Only issue I have is it doesn't reset to zero whe. The engine is off....it stays at around 1000rpm. Would that be right?....seems odd to me

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[mike202]

Any resolve to this? I have fitted the same Tacho. Only issue I have is it doesn't reset to zero whe. The engine is off....it stays at around 1000rpm. Would that be right?....seems odd to me

Sent from my SNE-LX1 using Tapatalk

I’m afraid it was down to user error on my part. I hooked it up to the wrong side of the coil. [emoji37]

It doesn’t help that the instructions are not that clear though, but it was just a silly mistake by me.

All working correctly now, the needle should drop down to zero when engine is off.

 

[Foz]

Any resolve to this? I have fitted the same Tacho. Only issue I have is it doesn't reset to zero whe. The engine is off....it stays at around 1000rpm. Would that be right?....seems odd to me

Sent from my SNE-LX1 using Tapatalk

I’m afraid it was down to user error on my part. I hooked it up to the wrong side of the coil. [emoji37]

It doesn’t help that the instructions are not that clear though, but it was just a silly mistake by me.

All working correctly now, the needle should drop down to zero when engine is off.

Negative side of the coil correct? Mine still isn't working correctly...perhaps it's a faulty one?
When I start the engine the needle shoots all the way round (from the 1000rpmark) round and off the clock....then back to around 2000rpm mark, so I believe it's showing 1000rpm more than its should be. Then on shutdown goes to 1000rpm where it stays.

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[mike202]

Yes the negative side of coil, which is the opposite side to where everything else goes !

Your tachometer sounds faulty so maybe a phone call to the manufacturer to ask for some help?


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[Bluesnailman]

Has anyone replaced the bulb in one of these? https://www.smiths-instruments.co.uk/products/volkswagen-bay-window-tachometer-grey-silver/

if so, is it a bulb that is easily replaced/swapped out?

i ask as I’ve previously changed my dash lights to red, and am contemplating buying one…… (I may need to take my dash lights back to white I guess)

 

[mike202]

the tacho has three screws on the casing so I would imagine would allow you to change the bulb. You could always email/phone them if no one on here has actually changed the bulb, just to check.

 

[Ben72Bay]

View attachment 7251the tacho has three screws on the casing so I would imagine would allow you to change the bulb. You could always email/phone them if no one on here has actually changed the bulb, just to check.

What about that grommet on the rear? Is that for bulb access?

 

[mike202]

I think that is only for changing the settings on tacho.