Brake lights tail lights not working properly

I would start with looking at the light failure sensor. It is located in the trunk, driver's side, tucked in on the inside of the quarter panel (pictured below). Inspect it, as well as all of the wiring coming to it and on the left side trunk hinge. This is a fairly common problem with these cars, and it causes all kinds of funky stuff to happen to the tail and brake lights.

Unfortunately there is no specific test spelled out that I can suggest to you. Both AllData and Prodemand fail in that respect. So you will have to kind of fumble around and try to test it. The part should be readily available at the local parts stores, and online as well.

Good luck and let us know how it goes.

Okay. Did this start when you did the bypass? If so, double check your wiring. Actually, you should double check your wiring anyways. Some wire could have become bare. Also, it is still a good idea to check the wiring around the trunk hinge on the left side.

Well all I can say is that there has to be some sort of wiring issue somewhere. You might have to start probing wires to find it, but it's there. I'll keep thinking if there might be any other potential issue.

Did you disconnect the wire from the taillights and then run that hot wire to the lights? If you didn't disconnect it first, and there's a short in there, then what you did would still send power through the shorted wire (as well as the lights). You'd have to disconnect/cut the wire and then run the hot wire to the piece that's still connected to the lights, if that makes any sense to you.

There is also a taillight relay inside the car. I'm trying to figure out exactly what it does, and if it could be the culprit, but I'm out of time for right now. I'm attaching an image that points you to where it is. You might see about testing it somehow.

Okay. I've done an excessive amount of reading and have found almost no real information on the taillight relay itself. What I have found is that it could be the problem, but I'm not sure of how to test it. I found one online for $11.00 here: https://www.partsgeek.com/gbproducts/MC/7943-07068874.html?utm_content=MC&utm_term=1987-1991+Toyota+Camry+Tail+Light+Relay+Standard+Motor+Products+87-91+Toyota+Tail+Light+Relay+1989&utm_source=google&utm_medium=ff&utm_campaign=PartsGeek+Google+Base&gclid=Cj0KCQiAr93gBRDSARIsADvHiOok08WvCoOeB6nkbaohDiVWIXIkjJxbTi-Q3MIxwwNfFXGF-n7hbYUaAp-rEALw_wcB&ad=47433949212

Personally, I would go ahead and buy it just to eliminate it, since I can't find any usable information on how to test it. Your local auto parts store should have it as well, although there will probably be a significant markup on it. I know this isn't quite the answer that you were looking for, but hopefully it helps.