I have a 2001 Pontiac Montana. The driver side brake light melts

Are the brake lights stuck on or are you just seeing the parking lights on without the brake lights lighting up? Sounds like you have no rear brake lights, check your emergency light switch. Sometimes it may not switch completely, turn it on and off a few time and then recheck it.

Replace the rear light assy socket panel, the Montanas have a problem with the plastic melting at the bulb contacts, I have replaced both left and right twice on my 2003 Montana!

check the fuse for the brake lights. then your brake light switch. Be certain the correct bulb was installed..and the socket for the light is not melted or deformed.

when the switch goes faulty the lights stay on all the time and as the brake bulbs light up brighter after a while would start getting hot and melt the wires and the earth wire is thinest.

could be a corroded socket or a broken wire on the socket. not sure. if you have a tester check to see if you are getting voltage at the socket. if you are the lamp may not be contacting the pins good. some have springs in the socket and they get dirty and wont move like they should.

you need a rear left circuit board. they come with new lights, and is generaly inexpensive20-30 dollars

It has melted. Having worked at a dealer I have seen this before. Dealerships deal with problems like this often .They will know the correct bulb to put back in to keep from melting the housing.

the boards in the tail lights have issues the plugs melt and they screw up the grounds. if your dash light signal indicators or on steady at night then chances are you will need new harnesses and light board assemblies

have you checked the bulb sockets to see if they are burnt or corroded sometime i see that the plastic melts around the contacts where the socket twists into the housing. if your lucky you might get away with replacing just the socket for the brake/running light bulb. but if it is too melted your most likely going to need a new housing

Often times the light socket assembly will become overheated in the Montana, (& Chevrolet Venture vans) and this will cause a bad contact between the light bulb and the socket. Sometimes it will also melt the plastic of the light assembly. If this happens, replace the entire assembly.

If it is not melted, sometimes just taking a screwdriver and pushing the light assembly contacts closer together will fix it - although in my experience you usually will end up replacing the light assembly after a little while (just putting off the unavoidable).

Many salvage yards should have this part if you want to save a few bucks.