The head lights becomes brighter, then a big flash, and its blown

the battery keeps going flat especially if the head lights are used
the engine becomes sluggish and starts to play up
hard to start ( slow crank speed)
a simple test is to ( at night) run the engine and pull the head lights on
if the alternator is not performing ,the lights will be dull and will not get brighter as you rev the engine up
If the lights do get brighter , then the problem may be in the battery
have it load tested
take the vehicle to an accredited auto electrician and have it tested properly.as it may be the regulator that is faulty.

check for a short/ bad earth in the brake light system/indicator system as it indicates that the 25watt brake light is earthing out through the indicator bulb making it brighter and overcoming the flashing power from the indicator unit.

Bad news!!! Blown head gasket. Sorry

it is overheating. low on coolant/ thermostat stuck shut? see if both radiator hoses are hot.

You mean the brake light is melting the plastic on the lens of the brake light? The head light is up front, It should not be coming on when you step on the brake, or be burning it out in any way, if it is, you got a major wiring problem. I think somebody put in a bulb that is too big, See it all the time, One is brighter than the other, check out the dim one and match it up on the other side. Hope this helps.

it is one piece of bulb, the brighter ones was burned-out or blown- out already what ever comes first. buy new head light bulbs and take it off the old ones.

you can get brighter and better bulbs for it without more watts silver star brand or the brite blue ones. the boxes the bulbs come in tell you how far ahead and to the side they shine. some of the good bulbs are like 30 to 49 dollars a piece. i put brighter bulbs in my jeep and they make a big difference. hope this helps. if you have questions ask your parts man at the counter which ones would be the best for you.

replace multifuntion switch

not sure what year this vehicle is so i would look under the bonnet for the power supply distribution box and check that out as the big power supply fuses are in their and i would imagine you have blown one of these big heavy fuses .

Check to insure a good ground on your rig, harness and trailer. Too many times the ball is used for ground, it doesn't work. Then I'd take it to someone else.