Truck is a 78 f150 4x4, 351M with a C6.

Problem: pull headlight switch out, only the headlights amd right parking lamp turn on. Low and high beams both work, and when I turn the hazards on, I can hear the flasher going. Replaced both turn signal and hazard flasher. Brake lights don't work, tail lights don't work, running lights on fenders and bed don't work. No blown fuses, would the headlight switch or brake light switch cause this? Thnks.

 

Try reading these:

<A HREF=http://i55.tinypic.com/21jw50l.jpg>74-78 Wiring Diagram Pt1</A>

<A HREF=http://i52.tinypic.com/35luc8n.jpg>74-78 Wiring Diagram Pt2</A>

 

Here's my take. In addition to checking the diagrams provided (and using the diagrams), the following are pretty good steps:

1. Check grounds everywhere. Corrosion, loose, disconnected.
2. Check sockets, especially in the back and main lights. Again corrosion, loose etc. Cheap replacements from the junk yard or parts store (well, these are cheap foreign parts but something like $8)
3. Loose, cut, or corroded wires along the way.
4. Finally, the turn signal switch in the steering column. I'd do this last because while others may go to this first, my limited experience is that this gets blamed first and it's usually sometime more simple. Check the connections under dash near footwell....and the connector there. If necessary and the unit has gone bad in the steering column, replace that.

 

2x with ^^^... and sometimes it can be as easy as reseating the connector(s). 'had a no-start condition with my 65 'Stang and reseated the firewall plug and it started right up. Upon further inspection (after I got it home), the plug was gunked up with road grime and airborne dust. Cleaned it, applied dielectric grease, and then fully seated the plug. Vroom!

I also used to fix $35 million jet fighters by simply reseating plugs. Magically, the problem would go away.

 

Problem was bad grounds and three bad sockets :/

Took me forever but I finally got everything sorted out, new bulbs all around, new flashers and a lot of new wiring.

 

When my headlights are turned on the hazards do not work. Turn signals work all around as do headlights and tail lights and reverse lights. I do have a slower than usual flasher rate.
Thank y guys
K

 

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