'00 chevy prizm, help!

I have a 2000 chevy prizm with 75,000 on it, and for some reason, it blows the tail light fuse when i turn on the headlights with the car off, but if the car is running, it will not blow the fuse.:banghead: This fuse just so happens to take out the instrument panel lights too. Any ideas?

My second thing is, this car didn't come with the overdrive transmission, and i want to put an over drive transmission in it. Has anybody done this? If so, what do i have to do other than get an overdrive transmission to make this work as smoothly as possible? Thanks in advance guys and girls! -Ozzy

Ozzy, Your tailight wiring must have a short somewhere, maybe in the switch? That's a good problem! Hmmm ... As for the 4-speed tranny swap. I looked into that very task myself. I have a 1999 3 speed auto. Why would anybody even bother with a 3 speed I wondered? Any way .. In my opinion it's too much work for the MPG you would gain. You need to swap the shift lever to get the OD button, Need the tranny of course. Need the computer for the OD gear circuitry and torque converter clutch parameters. Need the wiring harness for all of the above .. yikes. By now I've lost intrest in the job.
I get 33 mpg as it is. Let me know if you go ahead with it. I may follow if it's doable! DangerDude

Ozzy, Your tailight wiring must have a short somewhere, maybe in the switch? That's a good problem! Hmmm ... As for the 4-speed tranny swap. I looked into that very task myself. I have a 1999 3 speed auto. Why would anybody even bother with a 3 speed I wondered? Any way .. In my opinion it's too much work for the MPG you would gain. You need to swap the shift lever to get the OD button, Need the tranny of course. Need the computer for the OD gear circuitry and torque converter clutch parameters. Need the wiring harness for all of the above .. yikes. By now I've lost intrest in the job.
I get 33 mpg as it is. Let me know if you go ahead with it. I may follow if it's doable! DangerDude