How can you tell if the computer is bad and you need a new one ?

You have electrical problems. Not computer. The technician have to look at the wiring pictures and fugure out where circuit may cause problems. 2006 Toyota computer hardly goes bad. Look for the technician who has ASE L1 certification with a lot of experience. the price will very depending on the skill level. John 678-765-2100 Suwanee Auto repair