Stop lamps and sidelight circuits.

[rswaffie]

Hi All,
Having videoed the start-up and reversing out of the garage, a few feet up the drive, and back into the garage again (to send to my Dad by way of progress update) I’ve now noticed something odd/annoying/potentially time consuming to fix.
It appears that when I apply the brakes, the front sidelights and number plate lights also come on!
Given that the two circuits are separate (red wiring for the side/number plate lamps, green/purple for the stop lamps), is it more likely that I have connected the two circuits somewhere, than the stock answer of ‘bad earth’?
At the rear of the car, there are a few double bullet connectors so that’s where I’m looking first.
Could it be something else though?
Tia

[johnetype]

It could be that the brake light bulbs, the ones with the double filament, aren't in their sockets the correct way round or the filaments inside are broken and crossed over each other.

As a first action just remove both the brake light bulbs and see if the side lights still come on when you press the brake pedal, then replace each bulb in turn and repeat.

[chrisfell]

Check that the light units are adequately earthed. What could be happening is that the brake light is earthing back through the sidelight circuit. It is quite common with corroded lights on older British Iron after many winters.

[rswaffie]

Thanks all,
I think I’ve found what the problem might be. I checked that all the connections were correct, which they appeared to be. I then replaced the led’s in the stop lamps with the original dual element bulbs. Problem went away! So having spoken to the led supplier, he advised that there is a simple fix (similar to the fix for the led ign warning light issue) and he is sending me the bits.
Once fitted, I’ll report back with hopefully some positive news. This is the last electrical gremlin on the list so fingers crossed.

[rswaffie]

Just to close this off, I fitted a diode blocking lead between each red cable live supply and rear tail lamp red wire and the problem is fixed - no more front sidelights coming on with the stop lights.
Thanks to Gil at bettercarlighting for pointing me in the right direction and supplying the leads.
Hurrah, all electrical bugs now fixed.

[ralphr1780]

Richard, good that you have cleared this.
I have fitted led bulbs too, but did not face this issue. So it seems to be related to the quality of the led bulbs.
There is such a wide variety of these available out there...