"I had a problem with light boards in the rear lamps supplied by them, with the side lights off and when the brake pedal was pressed, not only did the brake lights illuminate, so did the front side lights!"

That usually indicates an earthing problem. I'd suggest that because the LEDs draw such a low current, some was 'leaking' to the sidelights. Because a higher current is required by the incandescents there wasn't enough to illuminate them.

No, it was not an earthing problem, the wiring on my car was all new anyway, tested it on the bench to prove, the fault was on the circuits to the light board, it affected two different types of light board, they seemed to sort out one of them as the replacement was fine, but the other, still unresolved other than my "fix" with using a standard bulb in the side lights rather than an LED.

A problem with the circuitry on the light board.

Location: Saltdean, Brighton

I had the same issue as Gary with the rear LED lightboard. My auto electrician solved it by adding a diode to the lightboard to stop the leakage from brakelight to parklight. Simple fix to a baffling problem which was complicated by my towbar and its attendant trailer lighting circuits. cheers Russell

Location: oz

I have used the combined Tail and Stop LEDs from Dynamo and Regulator conversions. Those supplied to me used a simple series dropper resistor to allow a 3 volt (approximately) LED to be used on 6 volts. Clearly, if the supply voltage varies as the engine revs change, the current through the LED will also vary a bit and some change in brightness will be seen.

One other thing to be aware of is that these particular LED conversions actually had just a single LED, with two different values of dropper resistor joined together at the LED live end. Thus the LED current (and brightness) will be large or small depending on which pin and resistor is being energised. Most of the time this will work as intended, however there is the opportunity for unwanted back feeding, depending on what else is connected to the side and brake circuits.

In my case I had a third central brake light with an ordinary bulb. This was back fed from the LEDs and robbed the sidelight circuit when the brakes were off, leading to no sidelights. I had to solve this problem by adding series diodes to prevent the back feeding before things would work properly. This only came about after a great deal of investigative work and head scratching which I could have done without !

Location: New Forest