Lights dimming when indicators on

Hi everyone
It's that time of the year when the dreaded MOT is due. Just noticed that my VL800 trike's lights dim when the indicator is on. The lights dim and brighten in sync with the indicator. I've checked connections and earth and they all seem fine, checked the battery and it appeared to be an original? Anyway, bought a new battery and charged it according to the destructions! But the problem persists. There are no other electrical problems that I can identify, trike fires up on the button with plenty of oomph, does any one have any further ideas ? Could it be the flasher unit? As always all comments gratefully received.

Are all of your lights dimming with the indicators or is it just the headlight? If it's just a single light then it's more than likely a bad ground to that particular light. Do you have any way of checking the voltage? If you aren't getting proper voltage when running (idle should be roughly 13V) then it could be a bad stator. I hope you get it figured out, electrical gremlins are the worst!

All the lights appear to dim. I will check voltage and see what i'm getting otherwise I'm scratching my head!

Hi Bill make yourself a temp earth and connect it to a good ground on your bike using the earth to go with your lights.It may work and is an easy way to check the earth.Good luck mate always a bad subject electrics.

I was going to say the same as Alfie, you have a bad earth. Run a new one.

I agree, run a new earth. Been there done that bought the Tshirt, several times years ago

Bit of an update. I thought at first it was all lights that were dimming but further investigation shows it is just the rear lights and the side markers, headlight and warning lights are ok. So with that in mind I made a temp earth for the the two rear indicators running the temp earth to a point on the rear chassis, no difference. I then ran it to the neg on the battery, still no difference. I did find, however, when checking the wiring that a previous exhaust had lain across the main wiring coming from one of the rear lamp clusters and had burnt through some of the wiring, this was under layers of insulating tape. I thought I had cracked it! But after using some connectors to rejoin the wires...... Still the same! I'll have another crack tomorrow. Does anyone think it is reasonable to think the problem is with the rear lighting/indicator setup rather than the front? Or am I being  thrown by my own, somewhat twisted, logic! Cheers everyone.