I'm not very good with electrical looking for some help.my back running lights on my 79 f 250 don't work checked bulbs and grounds also the heater does not work was told it blows but the switch doesn't work and lastly the signals don't work the hazards all work thanks for help.

 

Ok, so there's kinda three separate issues?
1. Back running lights don't work. Those are pretty easy to trace the wire back. Just check for voltage at the bulbs, if you don't find any, trace the wire until you find another connection point, check for voltage there, etc... until you do find voltage.

2. Heater. You need to figure out if it's the switch that's the problem or the heater itself. To do that, just measure the voltage at the heater with the switch on - If you have voltage, you know the motor doesn't work. If you don't, you know the switch or something in between is the problem, and the motor might work.

3. The turn signals. If all the hazards work, but the turn signals don't, my guess is that the issue would be in the steering wheel - pull the wheel off and have a look at the contacts where the turn signal switch is. When you get the wheel off, it should be pretty easy to figure out how they work, and you can check for voltage there.

 

2a Heater Resistor, check as well for various voltage




edit: Seems you might need to learn how to electrics! youtube multimeter, voltmeters, continuity meters and some basic electrical stuff, like wire schematic reading. I found on fordification a set of wiring schematics for several years which helped me immensely. Check those over to! if it don't make sense, think plumbing ... like electrons flow in the tube of wire and it goes somewhere (load) and then back out on a return tube.


Also, take pics of suspect areas, perhaps we can spot something!

 

Check and clean up any ground screws and around the hole where the eyelet gets clamped to. A bad ground can ruin a perfectly good day.

Get a electrical diagram and do the whole truck while your at it.

I've had those back taillight sockets be bad and they look perfectly fine until you put a test light on them.

 

Get yourself a wiring diagram and go to town. I bet it's some ground that has worked itself loose.

 

Ok figured out the signal .flasher was missing and thought I had back running lights .ok the black wire going into the plug broke off so I stripped it and shoved it back in the plug to see if that was it and turned on the lights.they worked then I turned them off and back on and it didn't work.