Erratic speedometer... Bad earth?

[teamlines]

So I've got an issue with the speedo on my S3. With the lights on and/or wipers on I get really bad electromagnetic interference. I've just replaced the dash lights with LEDs and the problem's become even more pronounced - so much so that with the lights on now the speedo over estimates my speed by 20-30 mph and the needle wobbles about all over the place! I'm thinking bad dash earth might be the cause but not sure.... Any ideas?

[swimmer27]

This won't help you Teamlines but if I put my headlamps on or heater etc my speedo jumps 20 - 40 mph.
I have gone through all the earths and even replaced a couple of cables but it still does it so I have a cheap satnav I use as my speedo.

[tvrgit]

Mine does this as well.

I used to worry about it too.

My solution was to stop worrying about it. 100% success so far.

[teamlines]

Thanks guys. I like the sound of the not worrying about it fix. Think I'll give it a go and see how it works out!

Ta

[Gerald-TVR]

Why not wire the headlights direct from the battery (fused of course) and use the existing wiring to switch a relay controlling them. This would hopefully improve your lighting issue and as a side effect supply a correct voltage to the headlights which could improve them from a single candle to a small chandler

[swimmer27]

Gerald-TVR said:

Why not wire the headlights direct from the battery (fused of course) and use the existing wiring to switch a relay controlling them. This would hopefully improve your lighting issue and as a side effect supply a correct voltage to the headlights which could improve them from a single candle to a small chandler

My headlamps (new last year) are actually very bright and give a decent bright wide beam of light!
But my wipers are pants, slow or very slow which always makes me laugh when I see the MOT tester switch them on and then wait for them to complete a cycle!

[Gerald-TVR]

swimmer27 said:

My headlamps (new last year) are actually very bright and give a decent bright wide beam of light!

Obviously not standard TVR then

swimmer27 said:

But my wipers are pants, slow or very slow which always makes me laugh when I see the MOT tester switch them on and then wait for them to complete a cycle!

Obviously standard TVR then