Decided to replace the trailer lights on my old utility trailer with LED's.

The lights worked when removed.

Installed new lights and replaced ALL trailer wires with a wiring kit.

Turn and Stop work fine when driving lights are OFF however when I turn on signal lights while driving lights on I get a pulsing effect from trailer lights.

I have not tried Brake lights with driving lights on.

Looking for a solution via Google there was a suggestion that tow vehicle ground might be bad. Cleaned and reconnected.

I have not replaced tow vehicle trailer light harness.

Any suggestions what may be cause and cure???

I have a tow to London and back this week and want good lights. There is no guarantee that whole trip will be in day light hours.  I curse all those I see with bad trailer lights so I don't want to be one that others are cursing

Pete g

Trailer light problems indeed are often a problem with grounding.

Does the car have separate bulbs for brake and turn signals?  If so, you need to buy a module that combines them for the trailer - available at CTC or any trailer shop.

I can bring a nifty test light with me tomorrow, if you like.