My son and I are working on finishing up a project truck we got from someone else. The previous owner completely stripped everything off the truck and painted the entire truck inside and out. He ended up selling the truck to us after having issues with the engine once he got everything together. We had a new engine dropped in and we are getting ready to have an inspection before we can register it, but we have an issue with the turn signals and brake lights. When each turn signal is turned on, a small amount of electric seems to be back feeding through to the other side turn signal. When we turn the headlights on and use the turn signal, all the turn signals and the license plate lights flash with the same intensity. We just found out today that the hazard lights do not work but with the hazard light switch on, none of the turn signals will work. Also, when we hit the brakes, both the front and rear turn signals light up.

We were thinking originally that this must be a ground issue, but once we noticed today that the hazards don't work I started to think that their might be an issue with hazard switch or wiring that allows the whole system to back feed? I'm lost at the moment and could use some systematic advice. Troubleshooting electric issues is not my strong suit.

 

Did the previous owner wire a receptacle for trailer lights in? That could cause at least some of the problems you're having if it wasn't wired properly.

 

No, there's no trailer harness on it.

 

Year make model !!

Did you unplug and test the switches on the column? (Headlights are switched ground, flashers are switched power)

 

86 toyota sr5 xtracab

 

Hazard-horn are usually on their own fuse. Does the horn work? That fuse is often in Relay Block 2, under the hood.

If the fuse is good, I'd first suspect a ground issue, then a problem with the switches. Try unplugging the hazard switch, then the turn signal switch, one at a time. Does it change anything?

 

Good. Always indicate truck-model-year-engine-transmission-trim to save everybody time.

This shows how normal headlight circuit behaves: https://www.yotatech.com/forums/f116.../#post52379293
Do the checks and let us know how different yours behaves. That would help us tell whether your lights have defective parts of someone screwed up the wiring.

 

Correct.
HAZARDS and HORN take power from fuse that always has 12V when connected to good battery
TURN SIGNALS take power from ENGINE Fuse (I know, Toyota liked to put circuits on branches that do not make sense).
You could have a bad / dirty turn signal , headlight combo switch, or shorts on the wiring to it.