Not sure what engine or year your solara is but on my 2001 V6 there is a switch on top of the transmission that activates the back up lights. Find the switch it has a hex head about 27mm on it then put the car in reverse if you do not get continuity across the terminals on the switch you need to replace it. The cost is about 20 dollars at advance auto parts (Part Number 2001 Solara V6: LS228). If that does not work get a haynes manual they have a procedure for the diagnostics.
here is a picture of the switch it should be right on top of the trans under the intake piping.
by katsolara » Mon Jun 30, 2008 9:49 am 
I put in back up switch and still does not work
