I have a pair of 91-92 T/A Taillights laying around in my garage and I have a base 91 Firebird with cracked taillights and was originally thinking of buying another set of the base set but thought since I have the T/A's lying around I would come one here and ask if anyone would know how/ and what I would need to change for these to work. Would I just need to change the harness? or do more wiring modifications?

 

The tail light wiring harness needs to be swapped. You need one from a TA. I think it's just a swap. The plug is on the driver side behind the tail lights.

 

If you have the harness, its easy.
If you don't, you'll need the sockets for the outer light on each side of the T/A lights.

 

I could be wrong (yeah, it's happened once or twice before), buttt, , , I seem to recall a wiring change needing to be done at the turn signal switch even if the TA rear harness is used? Something about the TA brakelights being different than the base model brakelights?

Anyone have any input on this?

 

I used the 92 tails in my 89 formula, only changed the outer sockets. No other wiring was required

 

This is what I was thinking of, but if it don't apply to the OP, all the better

https://www.thirdgen.org/forums/elec...hts-trans.html

https://www.thirdgen.org/forums/auto...ula-trans.html

 

85-90 TA taillights had the complex integrated wiring. 91-92 TA taillights don't have that; they're wired similarly to the 85-92 base taillights, with a separate amber turn signal, so the 85-92 base harness will work with minor modifications, as TTOP said. If I had to guess, it was probably for export purposes, where now, all versions of the taillights would be legal all around the world, so no more installing base taillights on TAs and GTAs that were built for export.

So, yeah, just swap the type of turn signal socket used on the 85-92 harness to the type used on the 91-92 harness and make sure wires are long enough to reach the 91-92 signal location, then remove the 194 tail bulbs and/or their sockets from the base harness, and it becomes "plug-n-play."