Toyota Repair: 02 Highlander brake light and engine light, vacuum hoses, light assembly

Question
I'm  having 2 problems.
1. the brake lights on the passenger side aren't working. I replaced the bulbs. The tail lights work, but not the brake lights. All other brake lights are working.
2. My check engine light is on. I had the code read and the guy said it was the gas cap wasn't clicked. He reset the code, but as soon as I got gas it came back on. Any suggestions?
Thanks for having this site in advance.

Answer
Hello, for the brake light problem make sure the correct bulb is installed in the socket, if so, there is another problem with the light assembly,these use an integrated light assembly that has one small wire harness connecting to the light then the wires branck off to each bulb. Disconnect the wire harness from the light and using a testlight or voltmeter check the voltage to the green/white wire connector with the brake pedal depressed, if there is voltage there then the problem is in the light assembly, you may be able to repair it if it's the problem depends on where the open circuit is or the light may have to be replaced.
As far as the check engine light I usually ask for a specific code number before making any attempt do diagnose but there are a couple of things you can try first if the codes are what I think they are:
Open the hood and check the vacuum hoses that are attached to the air filter housing, there is one coming up from the firewall that is supposed to connect to the top part of the fikter housing, it's very common for these to come off, next try replacing the gas cap with an OEM equivalent, remove the negative battery terminal for about a minute and go drive it as usual, if neither of these remedies work then I would need a specific code or code numbers to help more.