Originally Posted by Frango100
Not familiar with the 95 Grand, but you should try to find a wiring schematic. There is maybe a wiring break somewhere or a bad ground. You could check for voltage at the tail light socket first, to know if it is a voltage feed or ground problem. But i imagine that the ground for the tail lights will be shared with the other lights as well.
Anything showing up in the bulb monitor?
It can be misleading, and does a horrid job of telling you which rear bulb is having issues, but I would expect to be seeing something.
Pull the left [driver] rear lamp cover and use a cheap voltmeter or test light to see if you have hot circuit or not, start with hot to ground.
Then check socket ground to ground, which should have nothing. The ground on the left rear tends to be a problem, but I've never seen it take out all rear lights.
There should be a panel in the cargo area at the left light that has a bulb monitor in it, that can give you trouble as well.
Does the high mounted stop light have any bulbs light when you hit the brakes?
An open bulb in it can make other bulbs appear to be bad.
Unfortunately although I learned to "love" the rear wiring, never had the entire rear set of lights disappear.
It definitely helps to have a wiring diagram, the FSM is the best if you can find one online or used.