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Messages:1Likes Received:0I’m restoring my 75’ F100. I have replaced the wiring harness with a new Kwik Wire 14 circuit one. I cannot get my brake lights or hazards to work. The turn signals and tail lights work great. I have checked the brake switch with multimeter and it checks out good(the brake lights did work before also). I have checked the fuses, it’s a new fuse box. I have power to one side of the switch connector. I took a paper clip and jumped the connector and still no brake lights. I think the brake and hazards are together as I understand it. I’m pulling out the little hair I have left. Anyone have any ideas? Thanks.
I simplified the turn signal / hazard / brake light circuit diagram and posted it for 'ya:
- Orange is Turn signal Power Source
- Red is Brake and Hazard Power Source
- Green is the path to the brake light bulbs.
You say the turn signals work fine. So that eliminates any problems with the wires between the turn signal switch and the tail light bulbs. (Pictured in Green.)
If you have power (Pictured in Red) at the brake light switch, jumped the switch and still no brake lights, then it can be only three things:
1- Bad R-BK wire between the brake light switch and the turn signal switch.
2- Bad or Damaged Turn signal switch.
3- Incorrect Turn Signal Switch Wiring. Potentially R-BK (brake light power) incorrectly switched around with W-R (Emerg. Flasher Power) or similar error.
Ok, I finally got a chance to really tear into this. The turn signal switch is new also. I took the steering wheel off so I could check the turn signal switch, thought maybe a had a pinched wire. Everything looks good, when I push the brake pedal I have power at the R/B wire on both sides of the switch. So I know that the switch wiring is right. How can I have power there and the turn signals work but no brake lights. Is there something about wiring the bulb sockets that I’m missing. Using 1157 bulbs. Thanks for any help.
Turn signals use the same bulb filament and wiring as the brake lights, so if they work the wiring and bulbs are ok.
Double check on each side:
In the rear, does the parking light illuminate on the dimmer filament and the turn signals illuminate on brighter filament?
If so, the problem lies with the turn signal switch or it's immediate wiring. New parts, especially in today's market doesn't mean that something will work.
The hazards work in the front but not the rear. If when I push the brake pedal I have power on both sides of the turn signal switch so my turn signal switch wiring should be right. I have tried switching about every combination of connector wires. The w/r to hazards and the r/b to brake switch. Switched them around and made no difference.
Turn on the parking lights.
On the rear, the low brightness filament should be illuminated on each side.
With the parking lights on, operate the turn signal switch.
On the rear of the vehicle, along with the lower power filament illuminated for the parking lights, the high brightness filament should be flashing on each respective side L or R depending on turn signal switch lever position..
The front hazards do stop blinking when I push the brake pedal. I was referring the r/b connections on both sides of the signal switch have power when I push the pedal. I do have the bulbs wired right. One weird thing last night was while the left turn signal was flashing I had a brake light on the right side only, that’s the only brake light I can get so far. Doesn’t work without the left turn on and when the right is flashing the left brake light doesn’t work.. sorry about the long post and trying to explain what’s going on.
Also, the truck didn’t have a neutral safety and I wasn’t planning on putting on in since I will be the only person driving the truck. Does the neutral safety switch have anything to do with the brake lights.
I finally figured it out, it was the turn signal switch. I finally decided to take it out and take signal cam side apart. The wire on the R/B side of connector was broke. Weird how it could break, but it was. Ordered a new switch. Thanks for all of your time and effort into helping me figure this out. Dave
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