Toyota Repair: 2005 Toyota Corolla, electric door locks, brake warning light

Question
My girlfriend has a 2005 Corolla with an automatic transmission and electric door locks. When it rains or is very wet outside, the brake warning light on the dash comes on faintly when you take the gear selector out of park. The door locks also repeatedly try to lock the doors. The re-locking is sporadic but continues along with the dash light until it dries up outside. I assume the malfunction is in the auto-locking system.  I was wondering if this is a common problem and whether there is a part that I can check at home without spending a lot of money at a dealership for a tricky diagnosis. Any advice would be greatly appreciated.

Answer
I have not come across this same type of problem before but it's obviously some sort of electrical issue,first I would check all the fuses inside asnd the ones under the hood to make sure they are good and the connections are not corroded, also reomve some of the relays and check the electrical connectors, all of the body electrical functions, such as daytime running lights,auto door locks, warning lights etc are all controlled by the integration relay which is part of the junction block on the lower left of the dash where all the fuses are, check some of the wiring going to this relay block, check to see if any of the wires look burned or overheated, remove both the front kick panels on the sides and check the ground bus connections, they are black/white wires connected to the body, sometimes they feed a lot of ground wires into a large connector under the dash, they can corrode on the inside and cause intermittent problems, look for a bunch white/black wires that go into a connector that has no wires coming out, check on the inside of the connector for corrosion, this connector should be located under the dash on the driver's side, basically what I'm suggesting is that either there is a loss of ground or there is wire damage due to high resistance in some of the circuits which can be caused directly by a loss of good connection to ground.