You say you removed the trailer harness, was that before or after this issue? Did you also remove the T and C fuses? When you say no brake lights what about the high mounted one? Does it work with the key on?
The turn and hazard switches are simply grounds for the combination flasher unit. It is the brains of the lighting system on your truck. However they couldn't leave it alone so the wiring for the lights runs all over the place. If you still have the turn/hazard switch out where you can get to the wires you can do a couple tests to rule out a bad switch and fuses. It will require a simple cheap test light. First connect the light to a good ground. Now with the key off test the following fuses to be sure they have power on both sides, have been bitten by a bad fuse or fuse socket more than once, even when they looked perfect. Test fuse 4 in the dash fuse box. Then fuses 1, 5, and 6 in the power center under the hood. Now turn the key on and test fuse 19 as well as the others again. We are testing if the fuses all have power when they should, fuse 19 is a switched power while the others should be hot all the time.
Next go to either rear tail light and remove it so you can get to the wires. Take a knife and bare a spot on the Black ground wire. Connect a jumper from that wire to a known good ground and try the lights. If they now work there is a ground failure in the circuit which runs up to the front of the truck to a ground near the battery. Dodge are known for ground issues. If it doesn't work we will test the remaining parts to find the problem.
Take the turn hazard switch, unplug it and turn the key on. Be sure the test light has a good ground, In the connector find the Pink wire at terminal 1, touch the test light to it, this will ground the pin that tells it to turn on the 4 way lights. Do they come on? Now find the Light Blue with Yellow stripe on terminal 3 and try it, that should turn on the right turn signal, does it? Now the Light Blue with White for the left side turn.
If none of those work it is pointing more at the combination flasher, but we also need to be sure there isn't a short in the other end of the system. To do that find the combination flasher under the dash above the data connector. Remove the unit and unplug it. Use the test light connected to ground to test for battery voltage in the connector with the key on at the Black wire on terminal A6 and the Black with White wire on terminal A1
If you have power on both take a small jumper wire and go between terminal A1 and terminals A2 Dark Green w Red stripe wire then A3 Light Green wire. When those get power the Left rear brake and turn lamp and then Left front turn lamp should light. Next use that same jumper wire to connect to terminals B3 Tan wire for right front turn and terminal B4 Brown with red wire to activate the right rear turn brake light.
If those all light up without blowing the fuse then I would replace the flasher unit.
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Thursday, December 19th, 2019 AT 1:01 PM
