6.9 85 f350 no brakes or hazard lights

[Cainon]

Also this is the aftermarket brake box the previous owner installed. I've yet to see this thing power on. Do these only turn on when a trailer is hooked up? Are these known to cause issues?

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[IDIBRONCO]

I think the light should light up any time the brake pedal is pushed. At least the ones that I've seen in the past would do that. Your question would be easy enough to check though. Just unplug it and see if the lights work then.

 

[franklin2]

Don't worry about the relay, that is a red herring. That is for the trailer tow light wiring only. The poster that said it fixed his problem must have his truck lights being powered by the tow harness wiring back in the rear.

Also, don't mess with the hazard switch and it's wiring. That is a separate feed. You need power on the brake pedal switch. It's not going to work until you get power down there. I have had the wiring break going to the pedal switch. The wiring and the switch moves each time you use the brake pedal, and it can break in two over time. The fuse must be good since it's used by the hazard circuit also.

 

[franklin2]

You can see in the diagram below, the turnsignal switch is fed by 3 sources; The turnsignal flasher, the brake pedal switch, and the hazard flasher. They all need to be working for their functions to work.

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[Cainon]

I did unplug it still no brake light or hazard lights

Ok. So I've lost power somewhere before brake pedal then? And this will cause my hazards not to work either but my turn signals will still work?

They wired the box into the wires before the connector to the brake pedal switch. Is this something to look into removing?

I somewhat understand the wiring diagram. I get the color codes but dont understand the source to the brake pedal. And why the hazards dont come on but turn signals do. I know these questions are annoying. I do appreciate all the help. Just trying to fully understand

 

[Cainon]

I did just replace the column switch about 2 days ago. Maybe an issue with the U shaped connector? I checked it earlier and it was pushed all the way in. But maybe I'm missing something. I see others have hazards but no brakes. I dont have either. Really not trying to buy another $70 turn switch since this. One is only few days old.

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[dgr]

You should have power at all times on the LG/r wire at the brake pedal. You should have power at all times on the white with red you are probing.

Check you are using an actual ground and not just a black wire as they are often also power wires

I'd recheck the fuse if you don't have full time power to the White with red wire and one wire on the brake switch. I'd also be using a test light. Meters suck for this work. Fuse good, check the two wires at the back of the hazard flasher that feed the flasher and the brake pedal. That good, check the wires at your u connector haven't been pushed out.


My brake controller only lights up when a trailer is connected. Ymmv

Edit. Misidentified wire

 

[Cainon]

Maybe hazard relay behind fuse box?? I've been reading some other forums. Is this possible on my model/year? 1985 f350 6.9l dually.

 

[Cainon]

Hazard relay wasn't it either.... just put a new one in and still nothing. My red/white wire to the hazard switch is dead. All fuses are good. All switches are new. All wires are connected. I'm at a loss. Is the a fuse under the hood? Or some other relay on the passenger side or something I'm not checking?

 

[IDIBRONCO]

Is the a fuse under the hood?

Not on a 1985. As far as I know.

 

[Cainon]

Not on a 1985. As far as I know.

So probably the switch in the column I just bought a few days ago went bad already?

 

[IDIBRONCO]

It's starting to sound like it.

 

[dgr]

If you don't have power to the hazard circuit or the brake switch, your not going to have hazards or brake lights. Fuse 1 should have power at all times. If it doesn't, you need to head towards the battery. Check all your fusible links on the hot side of the starter and or glow plug solenoids and the fender apron on the passenger side.

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[dgr]

I'm confused. In this thread you're not getting power to the brake switch. In your other thread you are getting power to the brake switch.

A guy could run a known hot wire to the LG wire on the brake switch and that should feed power to the turn signal switch and through the turn signal switch to the brake lights.

 

[Cainon]

I wasnt getting power to the brake switch at first. Come to find out, the reader I was using was junk and unreliable. Bought a new reader and I have power the brake switch. And I should have power all times on the r\w wire in the picture I posted above but I am only getting a reading when that hazard switch is pulled out. But even then still no lights.