Brake light issues.
 

Hello, I own a 1991 volvo 240 sedan. The passenger side was slowly going out figured it was just bulbs, it was sitting so wasnt in a hurry to fix it but now I am trying to get it ready for inspection. Anywho.. the passenger tail was cracked a bit and the replacement of bulbs didnt work. Bulb after bulb started going out, its been raining a lot so i had thought it was maybe water getting in. I decided to replace both taillights with ones that I had wanted for a while so new tails and new circuit boards. However still the using the same bulbs and bulb holder sockets. Everything's working but the brake lights. However the hazards were acting odd at first, the left side worked correctly but the passenger side brakes were flashing and not the top indicator. since then after charging the battery that was dead while testing this in the beginning, the hazzards now work correctly again. All wires that are visible look good, the connectors on the sockets look a bit corroded and again old bulbs. The brake switch wires seem to look okay. I dont have a multimeter to check anything at the moment. Would corrosion or old bulbs cause this? Just a very odd issue. Maybe the brake switch?
i would much appreciate suggestions or possible fixes. I am hoping that it doesnt need a replacment of any wires as I imagine thats a pain to do.

without a volt meter, and doing a series of tests and working you way through the wiring, its really impossible to say whats going on.

btw, the new tail lights should have come with new bulb holders. I replaced all the lights on our 87 and the replacements came with everything. you /can/ clean off oxidized connectors, I use a clean soft pink pencil eraser, and DeOxit D100 contact cleaner/enhancer, the eraser will take off the oxide without damaging the metal plating, the deoxit keeps the connection good.