It sure acts like a ground problem also a messed up turn signal switch.
major light problem
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Cross-Country
Joined: Apr 2002
Posts: 83
Likes: 0
From: Canada
major light problem
[updated:LAST EDITED ON 02-Jun-02 AT 11:45 PM (EST)]I have a major light problem on my 77 f250 4x4. When i push on the brakes my parking lights come on. When the drivers side turn signal is on all my lights except the headlights and reverse lights flash. When my headlights are on, the driver side turn signal is on steady. Also when my lights are on the drivers side turn signal wont work. Its driving me nuts!! I've cleaned and or changed all the grounds on the chassis and the lights themselves. Its ticking me off. Is it a relay or something under the dash or something. Any suggestions to this problem? 
mike
mike
Posting Guru
Joined: May 2002
Posts: 1,300
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From: Southwestern Michigan
major light problem
ive had wierd stuff like this happen to me and it turned out to be the light sockets. changed them and the problem went away. I dont know if this will work for you but they are all probably still original. also check for trailer wiring in the back corroded and messed up
Cargo Master
Joined: Apr 2001
Posts: 2,364
Likes: 3
From: Eustis FL
major light problem
Once you've made sure all the bulbs are good, have a look at the passenger side signal bulb and socket. Use a tester if you have one.
If that doesn't cure the problem, go to the wreckers and find a signal switch. You will have to pull the steering wheel for this. I have seen two types of switch in the 73-79 range, so find the right one. Just unplug your switch (under the dash) and plug the 'new' one in without trying to mount it. Remember, this is just for testing. If it works, there's your problem. Signals and brake lights (hazards) run through this switch, and many strange things can happen when they go; trust me!
Mark
Ford started it; Ford will finish it!
If that doesn't cure the problem, go to the wreckers and find a signal switch. You will have to pull the steering wheel for this. I have seen two types of switch in the 73-79 range, so find the right one. Just unplug your switch (under the dash) and plug the 'new' one in without trying to mount it. Remember, this is just for testing. If it works, there's your problem. Signals and brake lights (hazards) run through this switch, and many strange things can happen when they go; trust me!
Mark
Ford started it; Ford will finish it!
Posting Guru
Joined: Sep 2001
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From: in the country
major light problem
If you have bad ground(s) the lights wouldn't work at all since the circuit wouldn't be completed---some idiot has tied the 12vdc output from the brake light switch into the clearance\parking light circuit------the lights don't care where the voltage comes from----the same idiot has cross-wired several different circuits under your dash----I think you will need to pull the instrument cluster so you can see the wiring behind the dash-------More than likely this idiot probably used those little splicer crimps and you will beable to trace the circuits based upon color codes of the individual wires---maybe it won't be too bad once you can see how everything is hooked up behind the dash!!!!!!!fd
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Senior User
Joined: Feb 2002
Posts: 133
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major light problem
I had a similar problem in my 76 F250, turned out the sockets needed a good cleaning and some of the bulbs needed replaced, also I cleaned the connector under the rear bumber where the forward harness attaches to the rear.
Now good as gold
Now good as gold
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Moderator
Joined: Jan 2001
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From: Virginia
major light problem
fatdaddy, the front turn signal lamps and the rear brake/marker lamps use a dual filament bulb. Both filaments have separate wiring leading to them, but are tied together in the bulb for the return path to ground. If you have a bad ground in the light socket, the electrical current running through one of the filaments, can actually run backwards up through the other filament, and find a ground through the other circuit in the truck, causing strange things to happen.
Posting Guru
Joined: Sep 2001
Posts: 1,531
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From: in the country
major light problem
Hells-bells as grandma use to say--sounds like a transvestite\engineer\chebby person designed the circuits for these damned ole' fords after he was fired by GM---!!!!!!What's the world commin'too???fd 
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Posting Legend
Joined: Sep 2001
Posts: 30,255
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major light problem
Actually the lights and electrical systems in those old Fords are absolutely rock simple, check out a wiring diagram. Mil1ion probably has one! All I have is some for an 85 E150. All of those old 70-80 fords are very similar. The problem with bad grounds and stray currents are universal. If anything I have found that the materials and workmanship are better in Fords than GM.
Electrical systems and failure symptoms can be very confusing to anyone without a knowledge of elctricity and basic Ohms Law and how to apply it. Enough to make one believe in gremlins, demons, ghosts, and evil spirits.
Electrical systems and failure symptoms can be very confusing to anyone without a knowledge of elctricity and basic Ohms Law and how to apply it. Enough to make one believe in gremlins, demons, ghosts, and evil spirits.
Thread Starter
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Cross-Country
Joined: Apr 2002
Posts: 83
Likes: 0
From: Canada
major light problem
Thanks for all your input so far. I've double checked all the bulbs and various grounds and they are all good. When i have a chance on the weekend i will check the sockets and then if i have to under the dash and so on.
mike
mike
Senior User
Joined: Sep 2001
Posts: 154
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From: USA
major light problem
Mike,
If you haven't already check the condition of the wiring harness from the front of the truck all the way to the back. I had the same exact problem with my '77 F-250 a few months ago. I tried changing all the sockets, bulbs, etc., but nothing seemed to fix it. When I checked the wire harness, I found where it had been chewed bad. Probably from a mouse when it had been sitting. The bare wires were rubbing against the frame and causing everything to short. I cut out about 18" an spliced new ones in. That solved my problem. Good luck.
Brendan
1977 Ford F-250 4X4
351M / 4-Speed
33" BFG Tires
www.angelfire.com/ma4/1977fordf350
If you haven't already check the condition of the wiring harness from the front of the truck all the way to the back. I had the same exact problem with my '77 F-250 a few months ago. I tried changing all the sockets, bulbs, etc., but nothing seemed to fix it. When I checked the wire harness, I found where it had been chewed bad. Probably from a mouse when it had been sitting. The bare wires were rubbing against the frame and causing everything to short. I cut out about 18" an spliced new ones in. That solved my problem. Good luck.
Brendan
1977 Ford F-250 4X4
351M / 4-Speed
33" BFG Tires
www.angelfire.com/ma4/1977fordf350
