Weird brake/ turn signal problem?

Well as u can read from title I'm having an issue with my 2004 Tacoma, after installing new battery my left turn signal began acting up now everytime I press the brake pedal it lights up where should I begin I searched the forum but nothing any suggestions would be much appreciated

**updated** FIXED
Battery had nothing to do with it BAD GROUND on rear driver side taillight
(turn signal socket)

 

I would check your trailer light connection if you have one.

 

^ what he said. something could have shorted.

 

No trailer connection it's a base model tacoma no tow package , already checked battery grounds , fuses and everything checked out turn signal relay was replaced 5 months ago could that be it ?

 

Just your front left turn signal lights up? Do all the other lights wotk correctly?

 

My hazards , right turn signal all working fine it's my left turn signal that acts up when the brake is pressed

 

Front and rear light? Left turn signal is normal?

 

LEFT( DRIVER side ) signal is the one that comes on when brake is pressed , u can actually see it light up in front LEFT signal light and REAR LEFT taillight

 

With out pressing on brake pedal, l key on engine off or running doesn't matter.. Does the turn signals operate properly?

 

Withought pressing brake pedal the turn signal works fine

 

One little Detail I left out is that after battery was replaced I took it for a quick spin around the neighborhood I had to turn left when I pressed down on the switch it made the the left turn signal act up thats when the brake problem began

 

You either have a bad body ground or a problem in the tail light assembly wiring or wiring harness for rear lights. Because the turn signal and brake lights are seperate circuits.

 

Exactly this. I have had these exact symptoms on 2 Tacomas. The ground is tied to the body near the rear tail light housing. Fix this and all will be good.

 

**UPDATE** well the problem has been fixed , the problem WAS a ground , the ground was the one connected to the turn signal socket in the rear tail light it was corroded so I removed, cut and recrimpped

Want to thank all of u guys for being super helpful thanks again

 

I had the issue exactly except that it was either turn signal flashing quickly when the brake was pressed and a search brought me here. I resolved mine today after removing the trailer converter box wiring (they ought to call it what it is: an isolator. It isolates the trailer and vehicle wiring). It wasn't that. It was a ground. I ran a jumper cable from the light socket body on the tail light to the trailer hitch receiver for troubleshooting and the lights behaved. A more permanent jumper was installed subsequently. I don't know the location of the original ground on the vehicle end. The bulb socket ground was okay, as in not corroded and it had continuity from the socket through the connector but not to the vehicle ground. Thank you to all who contributed here; it led me to the resolution.