Third Brake Light replaced but not working

Have you checked the electrical connector for presence of 12V?

Also, what does reasonably sure fuse is good mean? You need to know that it is definitely good. The above check is again your first step. If you do not have 12V present at the connector then pull the fuse and verify. If fuse is good then start verifying wiring and connectors back to the fuse source.

If you are not electrically knowledgeable you will need to take it to your trusted mechanic.

 

Take voltmeter and ar connector for 12 V when brake is pressed...you will need to have someone holding on brake and ignition on....
Second thing to make sure you have right part and it is working use test cables to see if new part is working...another thing if it is led light make sure polarity is in right order otherwise led will not function....


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Led light will flow current only one way so if you make mistake not knowing wich is hot and ground there will not be any harm..just reverse wires to with some source 12 V...car battery and two peace of wire will do the job

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The high stop light is on the same fuse and switch as the other two stop lights. If 12 V checks good at the light connector, check the chassis ground (center of back door panel per my diagram). My wiring diagram also shows a noise filter in series with only the high light. If no 12 V, look for that filter on the wiring harness in the rear luggage area--should be a light blue wire.

The stop lights are LEDs, so polarity is important, as noted.

 

I'm very familiar with the wiring of that circuit. After I got rear ended twice I put a motorcycle blinker on that third light only. So when you apply the brakes the brake tail lights lights come on as usual but the 3rd brake light flashes as many times as you like. You can set it, I have mine set to 5 times.
Very noticeable now when braking, Haven't been hit since and it's been 5 years.
Anyway on the back side of the hatch there's flimsy black plastic covers.
Take the top and bottom cover off and see if the wiring has been chopped up from prior accident. The covers just snap off. The brake 12 volt send comes in through the top center rubber protective tube. It's a blue wire. Goes through a plug then to the led third light. Unplug that plug with the blue wire and check for 12 volts when brake pushed there.
If 12 there to ground check the light ground point which is white wire with black stripe screws to hatch door frame right above license plate.

If no 12 on blue wire oh boy. It gets busy as it goes to junction connector in the trunk after going through noise filter n5 mounted above drivers brake tail light.

 

Attach the black lead of the DVM to the hatch body which is grounded and using the red lead and DVM set to D.C. Volts probe the blue wire.
It's on a plug right after it passes thru the rubber bellows. Unplug the connector and probe the blue wire on the car side for 12 volts D.C. When u apply the brake. No one to help you set up the DVM so you can see it you turn around in the drivers seat.
If u have 12 coming in to the hatch area thats good that means the problem is right there on the hatch probably the led assy is bad on the third light.

 

Don't use the lowest setting. You're looking for 12V, and most meters have a 20V range. Be sure you're set to DC, not AC. Test the meter at a known hot point, like the 12V battery terminal or the jump terminal in the fuse box under the hood.

 

I haven't needed to do this, but the basic concept is that you would remove the hatch lining trim so that you can see the wiring harness as it runs along the rear of the body, towards the hatch. Find where the blue wire joins up with the blue wires that run to the two tail light assemblies. That will likely be the source of your problem.

If you want to probe a wire and there is no convenient terminal to probe, use a thin needle to gently pierce the wire insulation so that you can measure the presence of voltage on that wire (by using the needle as a probe).

 

Clearly this is the result of whatever accident the car had for its salvage title.
This whack a mole will probably continue with other issues.
Buying a salvage title with little experience with tools will be very difficult.

Where was the car hit my guess drivers side rear?

Go to Toyota tech info.com and buy a 1 day subscription and get your printer ready for a workout. You can print out any parts of the service manual you need.

The brake 12 hits a junction connector in the hatch inside the tire well
Right below the hatch lock. A wire then goes from that junction to the drivers side rear light area up high to a noise filter. It will have 3 wires in it. One in
A ground wire and a blue wire. Guess where the blue wire goes?

 

Btw it is imperative u get that third light fixed as this car is a rear end collision magnet. It won't last long without that light.

 

Why not just run power from one of the other brake lights? Around the side, towards the roof and through the hatch.