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Brake light and turn signal problems.

Hello all. Im new to the forums here. This is my first Ford truck and so far i love the truck! its an awesome machine. Anyways i have a 1978 F150 custom 2WD standard cab truck.

when i bought the truck i picked it up for 600$ with a solid running 351m and minimal rust. well i drove it the night i got it and no dash lights? hmmm. also no brake lights? hmmm and turn signals were only in the front.

so heres my problem now. got the front blinkers working, and got one brake light and taillight working. But NOW heres the funky part. when i turn my headlights on the front turn signals light up, and the one rear taillight but when i turn the signals on NOTHING. flasher clicks and indicators in the dash flash. but no signals. BUT turn lights off the turn signals work good???

also why no dash lights? and when i turn the lights on the passenger side turn signal indicator in the dash stays lit??

I have cut and soldered on new bulb sockets on the taillights but only the drivers side works? and how come when my lights are on, brake lights and signals dont work?

NO blown fuses, tried replacing the flasher and that didnt help. bad headlight switch? any ideas?
 
You need to start tracing wires bro. It's the caveat when purchasing a 'bargain' truck :)

One thing to make sure of is the bulbs you use on your turn signals are dual filament. One shines brighter than the other - that's the turn signal filament. The one that's dimmer is the parking light filament. I've actually put the bulbs in wrong to where the filament roles were switched (blinker filament was dim and parking light overpowered the blinker).

The dimmer filament stays on when your headlights are on, but in order to see the blinker filament it must overpower the dimmer one - hence why it's brighter when the turn signal is activated.
 
thanks.

maybe i will try flipping the bulbs around. because the front signals are BRIGHT with the headlights on. so maybe i got them in backasswards? they are new bulbs and they are dual filament bulbs.

a new headlight switch is 14.99$ at the parts store, and i found a piece called an Instrument cluster voltage regulator? they are 44$ but i might try to junkyard one and see if those parts help.

I am really good with wiring, i come from working on nissan 240sx and toyota corollas and imports, and efi wiring and new car wiring is crazy compared to this old truck haha. Im for sure enjoying the truck way more then any cars ive owned! cant wait to do more work, just trying to figure out the lighting first of all.
 
Man I've had 5 or 6 of these mid 70s model Ford trucks and you can't beat em for simplicity and durability. Not to mention they just look friggin awesome. You will surely enjoy the experience...and quite possibly become an addict like most of us lol.

That regulator won't dictate what turn signal indicator you see lit up on your dash...it's for the gauges. Check out this thread here...may help you out.
 

TexasNomad

FTFS Designated DRINKER!
Didn't read it all or the replies so if, this has be covered sorry..
First check fluid and pressure .. if not then try the things that have plagued my truck at first and my friends trucks.
Is the socket its self, depending on type of bulbsocket is the connections that touch the bulbs are rusty or just not making good contacts and there is a ground in there to, all most all the issues with my lights have been bad connections, on every thing! Over time scum and rust works its way in to plugs and connections on every thing, try that first on every thing you think is bad before you go chasing wires.
 

LEB Ben

Arrogant A-hole At-Large
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Mike is right on the money, more than likely your issue(s) are crudded up contacts. So I'd go through and clean up every socket (personally, I just like to replace them at only $7 a piece), then clean out every plug (12-18" behind the headlights and the rear harness), then I'd check ground straps. I'd say about 90% of lighting issues in these trucks are caused by those things.

As for your dash lights, not trying to be a smartass, but did you twist your headlight switch all the way to the right? If that doesn't do the trick, time to replace some dash bulbs.
 
did some work today....

heres what i found:

fixed the drivers side lighting. brake light works, taillight works, turn signals work with both lights on and off. I had the bulbs in wrong or something but its working now.

Passenger side? Blinker work lights off, but lights on the dash indicator stays ON and the blinkers dont work? also no brake or taillight? BUT i have 12v at the socket and even in the socket. even spliced on NEW sockets!?! ground is good, ohm'd that out and checked the wires and the ground is good.

So i get 12v through the socket and the blinkers work lights off, but lights on no blinker no taillight no brake light?

My problem is a short somewhere causing the dash indicator light to stay on, which in turn i think is causing my problems. but where the hell is this short? its obvisoully still giving me power to the sockets and ground? its super wierd??

AND NO DASH lights still!
 

bucks77ford

We will Rise Again
Lighting can be an electrical nightmare in these trucks. Ben and Mike have already hit on great points. I'd also have to say that corrosion and grounding is almost always the problem. Even though you may think you have good grounds, sometimes you actually don't. One bad ground can lead to some really weird things and drive you nuts. I would say start with your grounds and sockets again (all of them, even the headlights). Make sure everything is clean and you have good grounds. Even if a ground wire looks good, disconnect it and clean it up. I've even just ran temporary ground wires straight from the battery or Chassis to eliminate using the body as the grounding source. You just want to eliminate the ground as a problem. Unfortunately, that can be time consuming and frustrating. Once you have done that, then I'd look into things like the the blinker switch itself, brake light switch, signal flasher on the fuse box and light switch.
 
so did some more work:

I have POWER and ground IN THE SOCKET, but no light from the bulb?? turn signal works when the headlights are off? i noticed some janky trailer wiring UNDER the truck, so im going to pull it out this weekend and see whats up. there are exposed wires and **** T'd into wires and 2 different trailer sockets back there.
 
i just saw this thread and was going yo ask if it has any trailer wiring.

that is a possibility
 

dakonthemountain

California Chapter member
Trailer wiring can really F&%$ up your electrical (including audio) system if it's not done correctly and maintained. Pull that all out first .You can always add it correctly later if you need it. Then trace your original wiring diagram. Double check all your grounds. Be patient. Electrical can be a real pain.
Good Luck!
Dak
 
A T/S indicator light coming on when you turn the running lights on means there is power feeding from the one circuit (brown wire) feeding power to the TS circuit on the side the indicator light comes on.
 
Hey guys .......my problem is my signals in the front.......when I turn my head lights on only the driver side signal lights up but don't blink.....neither does the driver side marker.....under my dash there are two places for flashers do I need both flashers for the signals to blink or wat...I have a 78 f 150 ........thanks
 
Hey guys.....I had a question......my blinkers don't work and under the dash there two spots for two flashers ARE THERE SPOSED TO BE and do I have to have both for the fronts to work.....thanks
 
Hey guys ......I have a question. My front blinkers don't work and under the dash there are two spots for two different flashers....... Is there supposed to be or wat.....thanks
 

Jasperrc

Texas Chapter member
Hey guys .......my problem is my signals in the front.......when I turn my head lights on only the driver side signal lights up but don't blink.....neither does the driver side marker.....under my dash there are two places for flashers do I need both flashers for the signals to blink or wat...I have a 78 f 150 ........thanks
If the turn signals work when the headlights are off, it's not a flasher issue. Sounds like a ground or short issue to me.
Didn't read it all or the replies so if, this has be covered sorry..
First check fluid and pressure .. if not then try the things that have plagued my truck at first and my friends trucks.
Is the socket its self, depending on type of bulbsocket is the connections that touch the bulbs are rusty or just not making good contacts and there is a ground in there to, all most all the issues with my lights have been bad connections, on every thing! Over time scum and rust works its way in to plugs and connections on every thing, try that first on every thing you think is bad before you go chasing wires.


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