Auto Parts: 1986 brake lights not working, turn signal switch, taillight assemblies

Question
Both brake lights on my 1986 Maxima have stopped working.  At the same time, the 3rd brake light on the windowsill was stuck ON....my mechanic fixed that but now he says it will cost either $300 or $500 to fix the brake lights.  He says one of two circuits needs to be replaced, but he won't know which one until he "takes it apart".  HELP!!! all this scares me--this car is my baby.....

Answer
    This is a little strange.  When the stoplights quit working, you can usually blame it on either a fuse or the stoplight switch.  But, for the high-mount stoplight to be stuck in the on function while the regular brakelights don't work is very peculiar.  I would be willing to bet that he fixed the high-mount light by taking out the bulb, which doesn't really fix it, but does keep it from draining your battery.  I think the problem is still in the stoplight switch, or possibly the turn-signal switch.  Or, you may have a shorted-out tail-light housing that is allowing current to run backwards through the circuit and light up the high-mount light.  Honestly, it could cost that much to fix, he's going to have to run down all of the circuits, probing them with VOM until he finds the point where the damage is and then fixes it.  There is a lot of variability in this, as he has no way of knowing how long it is going to take him, or how expensive the repair part is going to be (since he doesn't know which part he's going to replace).  I think that I would quiz him a little on what he's going to do, exactly, to find the fault.  At least you'll be going into it with a clear picture of what he's doing.
    However, before you let him go at it, look in the trunk at the backs of the taillight assemblies and verify that they are not broken or corroded.  Stuff rolling around in the trunk can hit them and, especially in a car this old, crack something or knock something loose.  While you're at it, look at the fusebox and the bulkhead connector (the block where the wires go through the firewall) and make sure that they are not corroded or damaged.  If you see any sign of damage, get him to look there first, it might save you some money.