02 impala no turn signals or brake lights excepet 3rd brake light in deck lid. the wire conector in trunk only had power on running lights. has a remote start system valet model 552t &what i think is a relay dei 555l. it does not look like it was well done but did work. is thier anything that ties brake & turn signal together? checked all fuses

 

All the brake lights EXCEPT the third run through the turn signal switch otherwise know as a combo switch. The fact that your turn signals do not work also would lead me to believe that is what is wrong.