9 replies to this topic

[colinu]

I'm trying to trace down an electrical problem that started recently... when I tap on the brakes the side lights (inside the headlights) are coming on too. Of course it's intermittent hence a bugger to troubleshoot. I think that I may have also seen the brake lights flicker briefly on when only the side or dipped beam switch was turned on. Sounds more like a 12V feed problem to me than a bad ground.

Has anyone seen similar before, or can someone offer advice where I should start?

 

And to further complicate things it does't have a standard loom. My guess is it's mainly an 80's loom - but I'm running a Smith's center speedo, Mk1 rear light conversion, and Megajolt ignition.

 

   Cheers,

   Colin.

 

P.S.

And to add to embarrassment I'm and Electrical & Electronic engineer so me and Mr Haynes should be able to figure this out for ourselves!!!

[russo]

Sounds like an earth problem to your stop lights. Check your tail lights are earthed properly. Also check the earth wires from your tail lights and loom are earthed. Thoroughly clean the surfaces of the chassis and terminals where they are anchored are also very clean.

[colinu]

OK, I'll have a rummage around the tail lights once it's daylight.

[minidaves]

or bulb has failed and the element has dropped onto the side lamp element 

[splintercat]

Got me stumped too.

can't see watt tail lites have got to do with the equasion tho.

if it were me I would disconnect sidelites and try yer brakes if they are earthing thro them    then they will either not operate or earth thro sowhere else.

if they don't wrk then chec your earth on the brakes / if they do earth out somewhere else then its yer earth on yer brakes .........well theres a little bit of logic in there at least. either rway I think its an earth job......phew I am just going to lay down for a minute.

[minimat]

Check the bulbs are both fitted correctly.

[KernowCooper]

When ever one circuit as you describe brings another circuit on then its always a bad earth finding its path to negative via another route, make up a earth jumper lead if you dont have a tester  which can provive earth and place it on the rear light earths to battery and try again

[colinu]

Solved ... turned out to be a 'bad' brake/tail light bulb in the rear LH cluster.

 

Bulb seemed to work OK (came on with tails and/or brakes) but when I measured the resistance between the bulb base and each element feed the brake filament showed 0.7 ohm compared to good bulbs which measure 3.6 ohms. New bulb fitted... problem gone 

 

However... the bulbs obviously run pretty hot 'because the seals around the housing have melted directly below the bulbs!!!  Might be worth fitting LED replacements instead of standard tail/brake bulbs???

 

Edited by colinu, 02 September 2015 - 12:11 AM.

[Steve220]

Have they melted or have they gone brittle and broke up? Glad you found the issue though :) Electrics can be a nightmare at times!

[colinu]

They melted!