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Any advise on Sapph rear lights issues 😞 (rainbow effect)

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Old 17-04-2015, 05:28 PM
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Tony Rs
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Default Any advise on Sapph rear lights issues 😞 (rainbow effect)

The problem is the rear lights go funny if I have the indicator on side lights and press the brakes they sort of dim between each other I have today cut the rear plugs off and attached them with separate little plugs and soldered it all in and added an extra earth from the body on each light and has made no difference also if I press the brakes and the handbrake is on the light on the dash dims too as well as the other dash lights this also happens if I turn the indicator on any warning lights on dash slightly dim anyone had this issue and managed to resolve it ? Are there any earths on the rear before I start tripping it all out

I have also today taken the speedo out and cleaned all the earths behind it and found an Earth on the passenger side footwell cleaned that too.

Any help much appreciated
Regards
Tony
Old 17-04-2015, 08:04 PM
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The Crocodile Hunter
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I've only ever know it to be bad connections or bad earth on the rear lights themselves.

I remember years ago have this problem on a mk3 escort and no matter how much a cleaned up the connections it wouldn't cure it. I fitted new 'bulb holders'?? And soldered in new plug connectors and it was all fine
Old 17-04-2015, 08:11 PM
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costina
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Deffo bad earth will give you the disco light effect.
Mainly found on anything french lol
Old 17-04-2015, 09:37 PM
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Tony Rs
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Ok I was thinking maybe getting some new bulb holders any idea if you can still get them from ford?
Old 17-04-2015, 09:43 PM
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Read before that you can solder a wire to the earth circuit on the bulb holder, with a ring terminal on the other end to mount under a suitable bolt...
Old 17-04-2015, 10:01 PM
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If you take your side carpet out and follow the wiring loom back. There is some joins in the loom. I had a problem with one of my reverse lights and i cut one of these joins out to fix it.
Old 17-04-2015, 10:03 PM
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Tony Rs
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Thanks for all the info lads ���� does anyone know which wire is the earth on the rear plug then wanna make sure I've used the correct one ��
Old 17-04-2015, 10:22 PM
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Don't know what colour wire, but you can trace back from the earth track on the bulb holder to the relevant wire in the multi plug...
Old 18-04-2015, 06:33 AM
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costina
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Brown is the earth.
Old 18-04-2015, 07:36 AM
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A separate 2,5 mm² earth cable from lamp carrier to the body shell will cure it for ever.
Old 18-04-2015, 07:44 AM
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Tony Rs
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I have noticed if I use the hazard lights instead there is no rainbow effect at all and everything works perfect ! But if I use one indicator only say left or right then I get the rainbow madness ! Looks like I was using the correct wire for earth too
Old 18-04-2015, 08:06 AM
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I have stripped loads of loom out of my pug and I have noticed a LOT of the ford wires are corroded a long way back in the loom, I suspect you have the same. It is the copper corroding I expect. Best solution may be to pull the interior and get an auto elec to replace the rear of the loom?
Old 18-04-2015, 08:10 AM
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I'd try the light backs first, easy fix.

I bought a few for spares, you'll pick them for around £15 a set
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