2004 F250 No brakelights/turn lights on trailer

This is most likely going to be an issue with the wiring to the trailer conector on the vehicle or the trailer conector on the vehicle

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My first guess would be a ground problem.
The headlights and tail lights are controlled by the same headlight switch, but the brake lights are on a totally different circuit.
You may have to get a shop manual to get the wiring diagrams needed to troubleshoot the circuits if the ground connections are ok.
The lights involve the body computer and other components.

the tail lights are the same bulb but they use a different filament in the bulb.you may need to replace the bulbs.another possibility is there maybe a problem with the wiring for the tail lights between the socket and the area where the trailer wiring is connected to the truck wiring.try the bulbs first,you just have to try one first to see it it works or not then you will know what to do next.

Unfortunately you will need to buy some form of wiring converter. To work with your trailer lights. The problem is that your Corolla has a separate turn and stop signal, Trailer lights have one wire for turn and stop. I suggest the CURT 56175 3-2 converter. You should be able to find it around 20 dollars.

Hello: Check the complete Connector (truck side) for excessive corrosion this is a common problem in areas where a solution is used on winter roads. It can be so bad the complete connector end may have to be replaced.

The basic 4-flat trailer wiring colors are as follows.
Yellow-Left turn/Stop, Green- Right turn/Stop, Brown-Running Lights and White-Ground
7-way trailer wiring colors are as follows.
Yellow-Left turn/Stop, Green- Right turn/Stop, Brown-Running Lights, White-Ground, Red or Black-auxiliary power, Blue-Trailer Brakes and Purple-Reverse lights

ck fuses . I think there are fuses for this. owners manual will point out which fuses. if no manual ck ALL the fuses with a test light, ign key on.

That would be my guess, take the plug apart and see if the wires may have come loose in the plug. Also check for corrosion, clean and lubricate area with grease or Vaseline.

Check your receptacle with a test light, to find out if it's the truck or the trailer that's the problem. If you have power at the truck, then take your trailer rceptacle apart, and see what's going on in there. If you don't find it in the plug ins, just work your way back with a test light. Its corrosion or a broken wire somewhere. Wiring can drive you nuts.

Not sure if you know that much about electrical wiring so I will go through it like you don't.
Take the trailer plug out of the female socket at the rear of the car, turn your running lights on, go to the female plug and using a test light check to see which one lights up the test light, that wire will be the running lights wire.
turn the running lights off and turn either your left or right indicator on and check at the plug to see which wire lights the tester, do this for the opposite indicator as well.
Turn the indicator off and get someone to hold their foot on the brake while you test the plug for power.
check the male plug at the rear wire terminals by putting it in the female plug and perform the same test as the female plug, if you have power to all the wires at the rear of the male plug go to the lights at the rear of the trailer and perform the same tests as before.
to get the both rear brake lights to come on you have to run a red wire from the brake light on the live wire side to the light on the opposite side to give it power when you apply the brakes for it to light up.
Turn the ignition on and turn your left or right indicator on again and check the wire for that side, if that is ok do the same for the other side then the running lights, you will have to run another wire off the running light wire to the opposite side of the trailer to give that side power to the lights
ther should be an earth wire from the plug that has to earth the trailer, all the lights also have to be earthed as they will not work if they aren't.
Try that and see how you go, if you do it right they should work for you