6.9 85 f350 no brakes or hazard lights

[Cainon]

I just replaced the column switch, all fuses, all bulbs, brake pedal switch. They were working for a couple of days and now I have no brake lights or hazard lights. Turn signals work fine. Running lights/parking lights, reverse lights all work fine. Any ideas? I do have an aftermarket brake box under dash for trailer hookup. Can that be an issue? Just bought this truck a couple weeks ago. Only has 144k miles. Also paid $1500 for the truck. I'm really happy with that. But out of curiosity, is that a good deal?

 

[franklin2]

The brake lights run through the turnsignal switch. First thing to do, get a testlight and probe the brakelight switch on the pedal arm. It should be hot all the time on one side, and hot on the other side when you press the pedal. If you have no power there, check the fuse.

If everything checks out at the pedal switch, then you will have to move to the column again. The lightgreen wire from the pedal switch goes up into the turn switch. Probe that wire while you press the brake, you should have power.

If you have power coming in, then with the turn switch in the mid position, probe the two wires leaving the switch going to the rear lights. They both should have power when the pedal is pressed. If you had power going in, and you do not have power on these two wires going out, your switch is bad.

 

[franklin2]

You didn't say what year you have, but I think they kept this same wiring and wiring colors for many years till the superduties came out. This is a diagram for a 1986. It shows the wiring colors going to the rear lights.

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[Cainon]

Thank you. I'll give that a try. It's a 1985 by the way

 

[Cainon]

Also, what would cause the switch to go bad in just three days? I took the wheel of again earlier and everything on the switch looks to be fine except the red and white wire by the hazard switch. Looks like my steering wheel rubbed it alittle but no wires are showing or anything. Just a very small flat spot on the red and white sleeve covering the wire.

 

[franklin2]

When troubleshooting, always go in with a open mind and trust your testing equipment. Make sure your testlight or meter is working properly, and then let it tell you what's going on. I like the testlights because the probe is sharp enough to poke through the insulation on the wire.

You never know, you may find the wiring plug is loose on the new turnsignal switch. You also may find your brand new switch is junk. It happens more and more with new parts these days.

 

[frankenwrench]

I ran into the same issue two years ago on my 91. Replaced rheostat replaced blinker switch behind steering wheel checked grounds and still same issue and fuses we're fine. I still recommend you follow franklin2 advice because it's good info/advice, but if all that checks out look at your little relay on the inner fender driver side for your tow package. That's what mine wound up being.

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[Cainon]

This here? Should probably be bolted down huh.

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[Cainon]

Also I checked the brake pedal switch (also only a couple days old) and dont seem to be getting any reading off of it. So I'm going to buy another one of those as well.


Turn signal switch in column seems to check out. Assuming that I'm only not getting a reading from the hazard white/red wire bc of brake pedal switch not giving a reading?

 

[Cainon]

If I'm reading some of these forums right. I should be getting some kind of reading from the brake pedal switch even if its completely out of the truck. Is this correct? So if I have it say on my table. Test it with the probe, push the switch down I should get some kind of ohm reading? Or am I way off? I am completely new to all this but really want to make sure i learn right and fix my truck up right and not just rig it to work.

 

[chillman88]

If I'm reading some of these forums right. I should be getting some kind of reading from the brake pedal switch even if its completely out of the truck. Is this correct? So if I have it say on my table. Test it with the probe, push the switch down I should get some kind of ohm reading? Or am I way off? I am completely new to all this but really want to make sure i learn right and fix my truck up right and not just rig it to work.

The switch should have very low or no resistance when pressed and should be completely open when not pressed (infinite resistance).

 

[frankenwrench]

Lol yes it should be bolted but mine wasn't either. Just went to the bolt bucket and found one and a nut to hold it up. Looks like the bolt is still there on urs though. You should get power to at least one of the wires coming of brake pedal switch at all times I believe. And both wen depressed as franklin2 mentioned before. If not then I believe your issue may be before the pedal switch in the wiring or a fuse or relay. But for s&g I would still check the switch how chillman88 suggested. And if the ohms doesn't read turn ur dial to check for continuity on the switch.

 

[Cainon]

Ty

 

[Cainon]

Next is relay. Just got back from part store. Picked up new pedal switch and still no brake or hazard. Probed switch in column and when I pull out the hazard switch (like I'm turning on the hazard lights) I have power at the wires but still no lights or brake lights. It's like I'm losing it somewhere between the switch and lights themselves.

 

[Cainon]

This is where I'm getting power when I turn the hazards on. And when I turn them off I lose the power. Just to be sure I'm checking right or wrong here is a picture of what wires I checked. All other turn signal wires I'm getting power to as well. So this switch should still be good right?

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