Electrical issue. 81 ford f150 step side.

[rouxel]

My friend has owned this truck for 5 or so years. He dropped in a crate 302 about 5000 km ago. truck has worked well the whole time. He only drives the truck maybe 1000 km a year. takes very good care of it for the most part. he is a smart guy (millwright by trade, as am I) so he very good at keeping up with the general maintenance of a vehicle. He ended up getting laid off and I took the truck off his hands. When we started it up (been 3 months since he last drove it) I noticed the tail lights were not working as well as the brake lights. I still took it off him because they have always worked and i didnt think anything of it.

now that I have it home I have found a few more problems that i need to get worked out. Ill try and explain the best I can.

Tail lights and break lights do not work at all. Front head lights work fine as do the lights on the dash. Front signals work fine but the rear signals are not working properly. When i signal either left or right the rear signals both come on as if the 4 ways are on. fronts work right but not the rears. I also noticed that the blink way way slower if my head lights are one. Probly 3 times slower. they blink normal if my head lights are off but flash very very slow if they are on. The last thing I noticed was the clock in the truck dims every time i hit the break.

I have not tried to much as I dont want to spend tons of money and time just guessing what the problem is. What I have done is. 1. replaced every single bulb ( front and rear signals, tail/break light bulbs and head lights). I also replaced the flasher relay and checked all the fuses. Im starting to think its a ground issue but not quite sure how to be sure of that. the only thing i can think of was about 3 months before I bought the truck I noticed that he had a live 10 gauge stereo wire kinda just flopping around and he didnt think it was live and wanted to prove it wasn't so he touched it to a ground and it obviously sparked like crazy. He didnt drive it in between that time and when i bought it. Could that have done any thing to cause this issue? Looking for some direction on where i should go from here.

Is there any other advice as to what the issue is?

All help is appreciated.

Thanks

Travis

[88jbody]

first place too look is if there is old trailer wirring in the back, on those older fords it shoudl run along the very back frame cross rail. if there is a trailer plug on the back, look inside it see if there is any corrosion or rot that could be arcing the left and right rear signals together.

then if nothing is found there unbolt the rear lights. then try and make a temporary jumper to ground from the metal housing where the bulb is. if it improves then you will need to make a new ground for the lights.

the other possibilities could be the bulb sockets themselves.

now remember all of this is subject to you already making sure all the bulbs are good.

if you are handy with a test light you can turn on the signal light and the tail lights one at a time and check with a test light if you are getting power correctly,

the most likely problem is a poor ground. if it had a poor ground on one side the signal may backfeed through the system to the other light to go to ground.

[rx7_turbo2]

Electrical issues in a Ford? I'm shocked

The issues are probably related to poor grounding. There's no easy fix usually since its rarely a single grounding point that's an issue. I'd start by checking the "primary" grounds, maybe even just replacing them as you go. Then it's going to be systematically checking every other ground at the devices.

Maybe I'm way off base and someone has a known issue for this, but I suspect the solution is going to be chasing poor grounds.

[rouxel]

ok, so I have spent some time trying to figure this out now and im having some trouble wrapping my head around what i have found. ill try and explain it as best as i can and hopefully someone can give me some direction.

first off i just wanted to mention that the right rear tail light has a decent amount of corrosion in it but not really around the bulbs themselves. these are a 3 wire tail light so does that mean its a self grounding light? grounding using the truck?



this is what i have figured out so far:

With the head lights and tail lights turned off as if im driving in the day light, when i signal either right or left both left and right lights flash just as if i have my hazards on and its very faint. can barely see them light up. I have my current tester that lights up red when i have current out and found out that my truck is live. I will connect to a ground and touch anywhere on my truck thats not painted and my light turns red. I can only assume that that is not right. So i was kinda just testing different things and found that when i touch my reverse lights to a ground both signals work perfectly and get nice a bright. when i apply the break they also light up but very faintly and my truck body is live then as well but when i ground my reverse lights they brighten right up (i notice that the bulb has 2 differant parts that light up, one dim and the other one gets bright) so when i ground out the reverse lights the bulb switches from the dim light to the bright light but the reverse light also comes one now. When i use my current tester when the brake is applied on the body of the truck it lights up but when i ground the reverse lights it dims.

now when i have my tail lights on as if im driving at night everything changes. the tail lights only work when the reverse lights are grounded and they work perfect. They dont work at all when the reverse lights arnt grounded. the signals also will not work at all until i ground the reverse lights and when i do ground them both signals come on as if my hazard lights are on. When i apply the brakes the bulbs turn off completely but when i ground the reverse lights they go dim except my reverse lights, they turn on nice and bright.

Can someone tell me where to go from here.

I forgot to mention that i completely took out all the wiring for the hitch.

other pics just in case im missing something