after 8 years of Restoration almost ready to start her up!!!! Both brake lights work...when brake pedal is pushed
left turn signal works fine..Right side brake light still on. when right side comes on brake light on left side stops working.....any Ideas??????

 

Brake & turn signals share same wire & bulb filament. The flasher interrupts the signal for the flash. I will start with grounding or the lack of. Check bulb contact area for clean contact. You need good grounding for things to work.




John

 

Both the parking lamps and the brake lamps use double filament bulbs (#1157). As John said, the brake lamps and turn signals use the same filament, the other filament is for the taillamps and parking lamps.

Remove the bulbs, use a pencil eraser to clean the contacts.

 

Same filament the circuit runs through the turn signal switch. If you go through all the basics & everything checks out she probably needs a turn signal switch. She is 40 yrs old.

 

Hey guys I'm new at this I've worked on old Ford cars and trucks for a few years and always figured out when something went wrong but I just got this 1978 f150 4x4 and I cannot get my break lights and turn signals working I've already changed the break switch and the two flashers switches for the blinkers and flashers and I've even pulled out my whole wiring harness from the back to the front of the truck. I followed my brake switch wires which r two red wire but one has a black line on one of the wires which I'm sure is a negative but followed it and it goes right to the dimmer switch I feel dumb for asking but can someone please help me?

 

Welcome to the forums.
You need to start with the correct year forum:
1973 - 1979 F-100 & Larger F-Series Trucks - Ford Truck Enthusiasts Forums

But, they all are pretty much wired the same basic way.

Not sure why the brake switch is wired to the dimmer switch for the headlights? That is just wrong. The dimmer switch should have the main power wire from the headlight switch going to it so it can switch from Lo beam to Hi beam. Nothing else. The brake light switch should actually go through the turn signal switch to allow the rear lights to blink when activated.

You removed all the wiring? Was the original harness cut up/destroyed? Sounds like it if things aren't working right. You might want to post in the other forum, maybe someone has a wiring diagram they can show you.

 

Sorry I don't have any wiring diagrams for a 78. The other forum can help you better. Let us know when you find out what the problem was.

 

Okay thanks anyways guys and I will when I find out what it is