Owners of other General Motors vehicles or any other American or foreign vehicle may also find this guide to be useful.

I am not a professional mechanic. I take no responsibility for damages or injuries. Proceed with caution.

The moisture must have entered the tail light assembly due to the rubber seals around the light bulb housings becoming old and brittle. The high humidity and heavy rains in South Florida don't help the situation either.

I had this same problem with water condensation inside my car's headlights a few years ago. To correct the problem, I had to completely remove the headlights from the car and dry them out indoors with a hair dryer.

To prevent the humidity or rain water from entering again, I wrapped the outer ring of the headlight bulb sockets with some Teflon Tape (a.k.a. Plumber's Tape).

I repeated this procedure with my tail lights as detailed below.

The headlights were still free of any water droplets or mist since I wrapped them a few years ago to re-create the seal.

I didn't remove them to check the condition of the OEM original rubber gasket for fear of damaging the Teflon tape's barrier to our area's high humidity and torrential rain storms.

To take out the three headlight bulb sockets (low beam, high beam, & signal), just hold the small tab and turn the grey socket housing a 1/2 turn counter clockwise and lift it straight up.

To remove the tail light in a 2001 Pontiac Grand Prix or any General Motors car, you'll need to open the trunk and locate the large black plastic thumb screws.

In my car, the top tail light thumb screw was visible at the top rear corner of the trunk.

I removed this screw by rotating it counter clockwise with my fingers.

To access and remove the second of two tail light thumb screws, I peeled back the trunk's carpeting.

The three bulb sockets (parking, brake, reverse) on the rear of the tail light housing can be removed in the same manner as the headlight bulbs by holding down the plastic arm and rotating them counter clockwise.

To help speed up the water removal from the tail light, I used a hairdryer set on high heat and blew hot air into the socket holes.

Be sure to periodically move the hair dryer to different sections of the housing or take short breaks so that you don't melt the plastic.

I didn't have time to wait overnight for the tail light assembly to dry, but that would have been a much easier and safer method for completely removing all the water.

To create a new airtight and water tight seal around the tail light bulb sockets, I wrapped the outer ring of the socket with the Teflon tape.

For the best seal, it's important to wrap a turn or two of plumber's tape on the inside surface of the socket where the old rubber gasket rests.

It's better to have too much Teflon tape on the bulb socket than not enough.

Putting on too much Teflon tape may require either more force to twist the socket into the housing or you'll have to remove some of it little by little.

If the socket turns into the tail light housing too easily, you probably don't have a good enough seal and should add more tape.

To remove that moisture, I thoroughly blew them out with a can of "Dust Off" compressed air.

Then I inserted the tail light bulb sockets back into the dried out housing with firm pressure and twisted clockwise a half turn to the locked and closed position.

To finish up the job, I put the assembly back on to the car and secured the two thumb screws.

If you've done a good job of applying the Teflon tape, there should be a tight enough seal to prevent rain water, humidity or condensation from getting inside your automobile's headlights or tail lights.

Update - This initial repair attempt did not work completely. The tail light eventually gathered some more moisture inside of it over the course of a few weeks. I believe that my second attempt has permanently fixed the main cause of the issue. I removed the tail light, and dried it out over night.

I made a note of where water was leaking out from between the clear plastic lens and the black body of the tail light when it was drying out in the bathroom.

The next day, I used several tubes of crazy glue to re-seal the lens to the tail light assembly.

For extra reassurance, I sealed the open areas of the bulb sockets with high temperature silicon sealant to keep water from entering that area and rusting out the contacts.

For more, check out all of my Pontiac Grand Prix DIY Repair & Maintenance Guides.