lower brake light

my 2001 altima's lower stop lights won't come on. i have changed all the bulbs in the upper and lower and still nothing. how do i find the problem. i had a diagnostic and i got 4 codes, 446,464,1490,0505.

Are you certain that you have the correct lightbulbs? Use a test light to find where you do have power in the circuit and where you don't. Start in the back and see if you have power to a light socket when the brake pedal is pushed. Check the ground side connection from one of the light sockets and trace it back to the bad connection. Using a DVOM and a test light may be a big help. Very likely the top and bottom lights are seperate circuits with seperate fuses so that if one fails the other still works for added safety. Both circuits use the same switch. The stoplight switch may have two seperate circuits built into it. Maybe one side is burned out.

[QUOTE=JustSayGo]Are you certain that you have the correct lightbulbs? Use a test light to find where you do have power in the circuit and where you don't. Start in the back and see if you have power to a light socket when the brake pedal is pushed. Check the ground side connection from one of the light sockets and trace it back to the bad connection. Using a DVOM and a test light may be a big help. Both circuits use the same switch. The stoplight switch may have two seperate circuits built into it. Maybe one side is burned out.

[QUOTE= cedric] thank you, i have done the tests you suggested. but i think i got the answer i was told that the turn signal switch has that circuit intergrated into it and if i test the switch i will find the problem there. you said:Very likely the top and bottom lights are seperate circuits with seperate fuses so that if one fails the other still works for added safety is rite, but its on the turn signal switch