So I have a 99 deiscovery sd from what I’m learning it seems to be a mix between a discovery 1 and 2? When I turn on the turn signals either left or right doesn’t matter a trailer light comes in then goes back
off... every other vehicle I’ve owned in the past has a button to enable “tow mode” I’m assuming that’s what the light means... but, I don’t see a button... I’m not seeing anything in the owners manual about a tow mode... perhaps I’m missing it? The manual seems to be written backwards lol

 

the trailer light illuminates automatically when extra load is detected on the turn signal circuit. it goes on and off as the turn signal goes on and off. at least on my truck, when the brake is applied at the same time as a turn signal the light will not illuminate.
there's no button for trailer mode.

 

I don’t have a trailer hooked up... I’m assuming there’s a bad connection somewhere that’s making it think there’s an extra load on the circuit?

 

or someone might have put the wrong bulbs in.