Hi all,
Been a keen reader of this forum for a while, but apologies nonetheless for making my first ever post a cry for help!
I have a 1998 Honda Civic 5 door which is normally flawless in operation, but I noticed that as Mrs Plums dropped me off at work this morning that the brake lights were permanently ON.
Fiddling about this evening, the exact fault can be described thus:
brake lights work properly with sidelights OFF, but also cause the dashboard backlights to illuminate.
with sidelights ON, brake lights are always ON, but get marginally brighter when brake pedal pressed. Dashboard lighting works as normal.
I'm guessing there is an earth fault - probably where the rear sidelights and brake lights share a ground. Am I barking up the right tree here? Found the location of the likely grounds G503 and G504 here:
www.honda.co.uk/owner/CivicManual/pdf/23-a28.pdf
But there's also a ground in the bootlid for the high level brake light only. I think this may have been removed and refitted last year for an accident repair, so should I look at this first - not sure if it could cause the sidelight issue?
Hope someone can help, thanks for reading!
Cheers,
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Could be Broken bulb filament has shorted on to the other..Check your bulbs out before suspecting anything else.As it is often the case?
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Steve
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great idea - the brake and sidelights do share dual filament bulbs...
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Sounds like an earth issue on one of the rear light clusters.
When you apply the brakes +ve routes throught the bulb to floating earth (not connected between bulb earth and car body) then back in to the side light side of the bulb and onwards back to the dashboard to illuminate the other lights.
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Set aside an hour for tinkering this afternoon, only to fond tha the problem had self-resolved. I'd still like to pre-empt a recurrence by checking through the connectors though...
Big John,
I'm not sure what you mean by "floating earth". It was my understanding that (working correctly) the current flows from +ve through the bulb, then through the black to the earthing terminal. Is this correct? I was prepared to check the connection of sidelights and brake lights to the earth terminal. Should I be looking elsewhere? I'd have thought that if there was a simple open circuit on the earth filament, the current couldn't go anywhere else.
Also I presume that the fact that the problem has self-resolved (maybe even if its only temporarily) rules out issues with the bulb itself?
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The earth return is through the car bodywork. If this connection is broken/dirty then the current will take the next easiest path it can find. (A floating earth)
Sometimes this is through adjacent filaments, wiring, etc. This gives the fault where odd lights illuminate when they shouln't, ie the indicator bulb will glow when the brake lights come on.
Usually each rear light cluster has one main earth. it is probably worth disconnecting this from the bodyshell and cleaning the fixing point and the connector.
The front lights will probably have several earths due to the current drawn by the headlights. It may be worth finding these and cleaning them as well.
The bulbs may well benefit from a clean around the metal caps where they connect into the holders.
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I presume they are working correctly now..Did you check the filaments of the bulb. As sometimes they can break away from the other filament. though leaving one light not working/either stop or tail..On occasions a single filament bulb fitted instead of double will do the same thing..as for current flow its negative to positive..Not sure about Floating Earth. I cant say I have heard of that before..No Doubt it will be explained..As a PS are you sure no water got into the light clusters?
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Steve
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A quick update - it was the bulb!
Both filaments were intact, but there were scorch marks around the inner glass bulb around the base of the filament holder. New bulb rectified the problem.
Thanks for all your help. Used the time set aside for wiring checks to clear up the garden and feed the birds, so your kind advice has made some feathered critters very happy!
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