No stop lights or horn after rebuild on '66

[Gas Pig]

Ok doing a full rebuild on a Sep. build '66 U13. I'm in the final stages of testing electrical but I have no horn or stop lights. I did put in a new turn signal switch when I rebuilt the column. Also carefully went through the original dash harness, engine bay harness for broken connections all seems to be good.

So everything works as they should turn signals, running lights, headlights, and tail lights, even all the lights in the cluster but stop lights or horn. I'm getting 12v to the circuit that powers those two components. These both should work if the bronco key is "on" and/or "off" but no go in either case.

Any help would be greatly appreciated!

Thanks Jeff

 

[DirtDonk]

Do you still have the original pressure switch out at the master cylinder?
If so, try jumpering the wires there to see if the brake lights work. If they come on when you connect the two wires at the switch together, then the switch is not working properly.
This would be due to either an old defective switch, or not enough pressure build up in the brake hydraulic system.

New horn or old? Well grounded through it's case, or is the area all new paint?
You need to verify where the power is stopping or we won't know anything further. Check to see if 12v is getting to the wire connected to the horn. If not, then there is a problem upstream. Check the wires again and see where power is going up into the column and see if it's coming back out.

Assuming this is still a stock wiring harness? Sounds like it, but aftermarket harnesses would have their own relays and function differently than your original.

Good luck.

Paul

 

[kip60]

I had an issue with brake lights only and it was the ground. Turn signals operated on one side, but not the other. Brake lights didn't work at all. That threw me a bit. Why would the blinker work, but not the brake light? So I knew the bulb worked. Then I just started at the tail light and worked my way backwards. If you take a tail light out, there is a screw that grounds each light to the body in the cavity behind the light. I took out the screw, sand papered the hole and the terminal and everything worked fine. Probably won't help with the horn, but that could also be a bad ground somewhere.

 

[Viperwolf1]

Check the 6-pin column connector. You should see 12V on the brake wire (green) there when the brake is pressed.

Horn power wire is yellow and should always have 12V.

If those inputs are good chances are the turn switch is bad in regard to the brake lights. If the horn output (blue) wire has 12V when the horn button is pressed you need to follow that wire through the bulkhead connector to the horn and check the horn ground. No voltage at blue wire indicates a problem at the horn switch.

'66-'71 Column Connections
Light Blue=12v from turn flasher to turn switch, circuit #44
white-blue=right front turn and indicator lamp, circuit #2
orange-blue=right rear brake and turn lamp, circuit #5
green-white=left front turn and indicator lamp, circuit #3
green-orange=left rear brake and turn lamp, circuit #9
green or red-black=12v brake switch to turn signal switch, circuit #810
yellow=12v headlight switch to horn switch, circuit #460
blue-yellow=horn switch to horn, circuit #482

 

[Gas Pig]

I haven't got a chance to get back in the garage to test the brake lights circuit but I know for sure I do not have 12V on the yellow wire to feed the horn button. Anyways early today I had unplugged the 6 pin column connector to check voltage and ring out the wires. With the key "on" I do have 12V on light blue wire that feeds the turn signal switch... and all of the signals work great even the indicators on the cluster. But while I had the power on the pin that feed the signal switch I jumpered it over to the wire (blue) that goes to the horn and it sounded. So obviously I'm missing something in with the yellow going to the column plug end. I saw in the '66 wiring diagram that the yellow like you said comes from the headlight switch. What I'm not understanding is how the yellow wire is being fed the 12V... is being power though the headlight switch from an internal contact?


Anything thing I should hunt down on why the yellow wire is not getting 12V?

Thanks for everyone help! Jeff

Check the 6-pin column connector. You should see 12V on the brake wire (green) there when the brake is pressed.

Horn power wire is yellow and should always have 12V.

If those inputs are good chances are the turn switch is bad in regard to the brake lights. If the horn output (blue) wire has 12V when the horn button is pressed you need to follow that wire through the bulkhead connector to the horn and check the horn ground. No voltage at blue wire indicates a problem at the horn switch.



'66-'71 Column Connections
Light Blue=12v from turn flasher to turn switch, circuit #44
white-blue=right front turn and indicator lamp, circuit #2
orange-blue=right rear brake and turn lamp, circuit #5
green-white=left front turn and indicator lamp, circuit #3
green-orange=left rear brake and turn lamp, circuit #9
green or red-black=12v brake switch to turn signal switch, circuit #810
yellow=12v headlight switch to horn switch, circuit #460
blue-yellow=horn switch to horn, circuit #482

 

[Viperwolf1]

Correct, yellow wire comes directly from the headlight switch. Should not be any connectors or other wires coming off the yellow. You may want to measure voltage on it at the headlight connector. Could be a cut wire, bad terminal at the HL switch, or a bad HL switch itself.

 

[Gas Pig]

Correct, yellow wire comes directly from the headlight switch. Should not be any connectors or other wires coming off the yellow. You may want to measure voltage on it at the headlight connector. Could be a cut wire, bad terminal at the HL switch, or a bad HL switch itself.

Got it!!! Both horn and brake lights. The headlight switch is a NOS vintage motorcraft so I pulled it back out from under the dash. I tested both the switch and wiring with my meter and everything was good. So I plug it back I while everything is still hanging... she work great. My best guess maybe the harness plug to the HL wasn't fully seated before. Hopefully once I put it back together she'll still work.

Thanks again I'll give s final report a bit later.
Jeff

 

[Gas Pig]

All good now

Yep all good now all I had to do is tighten up the wire terminal on the harness plug end connector and everything works great now!

Here is a pic what I'm working I wish I could pre test it more thoroughly before it goes into the truck. It was a little disheartening at first when the dash is all and ready... then this happened. It was a easy fix this time but think of the nightmare it could have been if I had a broken wire somewhere.

Thanks again for your guys' help!

 

[Viperwolf1]

Very nice.

 

[Gas Pig]

Very nice.

Thanks!!!

 

[MyOriginal66]

Wow. Another beauty, jeff. Can't wait to see the final product