brake light goes dim

my left brake light gets really dim when i hit the brakes, the running lights and blinkers work fine. i thought the running light and brake light used the same bulb? and i replaced it with no luck. i also thought there was only one fuse for both brake lights, or is there a fuse for each that may be bad?

there should be a smaller bulb for the running lights as well that doesnt do anything but light up. the main brake light bulb also doubles as a running light and gets brighter as you press on the brakes. the bulb might be bad. i have LED bulbs in my truck and it did this same thing...only half of the LED's worked (the running lights) and the brake side of it had burned out. i just replaced the bulb and now everything is back to normal. also when i first got my aftermarket buckets, they had the wires backwards which cause my brakelights to act as my running lights and i didnt have any brake lights what so ever because they were already as bright as they could get. look at the wiring if the buckets are aftermarket.

only the left one? plug your right tail light in and see if it is the same way. id check all your plugs and pigtails. maybe there isnt good contact or a bad light socket,

Check the ground on that light.....Toyota usually uses a white wire with a black stripe on it for ground. Make SURE its grounded well.

yea its more than likly a ground problem most dim light are.