84 F150 Brake light issues

[Crixmix]

So hoping someone might have some info for an issue I’m having. My brake lights randomly stopped working. Naturally I switched out the bulbs and fuses and still no luck. Also my left turn signal is working but not my right and the bulb is the same for brake and signal but I attribute the right signal not working to a broken turn signal cam. So then I replaced the brake switch and still nothing. I realize this is now probably a wiring thing but I have no clue how to find the issue as I’m electrical is not really my strong suit. Any help or info would be greatly appreciated

[ArdWrknTrk]

Chris, have you changed the turn signal switch in the column?

Are you sure that all the pins and the ground wire there have a good connection?

There are variants of the brake light wiring, and I'm going to ask if you have Speed (cruise) Control in your truck.

There was a recent thread about a very similar problem, with some very good diagnostics.

Let me see if I can find it.

[Crixmix]

Chris, have you changed the turn signal switch in the column?

Are you sure that all the pins and the ground wire there have a good connection?

There are variants of the brake light wiring, and I'm going to ask if you have Speed (cruise) Control in your truck.

There was a recent thread about a very similar problem, with some very good diagnostics.

Let me see if I can find it.

Hello

Yes I’ve replaced the switch once before and it seems it has broken again. The left turn signal stays in place and works but I have to hold the handle up to activate the right turn signal. Both indicators on dash flash but only the left signal turns on.

Yes I do have cruise control but it doesn’t work at all

[myrl883]

Hello

Yes I’ve replaced the switch once before and it seems it has broken again. The left turn signal stays in place and works but I have to hold the handle up to activate the right turn signal. Both indicators on dash flash but only the left signal turns on.

Yes I do have cruise control but it doesn’t work at all

If you look at the wiring diagram, power feeds the brake light switch, then goes to the turn signal switch to be split left and right. The turn signal switch controls the brake light whether the turn signals are on or off. So, a turn signal switch can cause all sorts of problems with the brake lights.

[kramttocs]

Hello

Yes I’ve replaced the switch once before and it seems it has broken again. The left turn signal stays in place and works but I have to hold the handle up to activate the right turn signal. Both indicators on dash flash but only the left signal turns on.

Yes I do have cruise control but it doesn’t work at all

Do you have a multimeter? That will come in handy. For something like this you won't need a fancy one - voltage and continuity. A light up circuit tester will work for some tests also if you have one of those.

If you pull the hazard switch, any different behavior?

[Crixmix]

Do you have a multimeter? That will come in handy. For something like this you won't need a fancy one - voltage and continuity. A light up circuit tester will work for some tests also if you have one of those.

If you pull the hazard switch, any different behavior?

So I replaced the turn signal switch

Both turn signals now work. But still now brake lights. And yes I do have a multi meter just don’t know what and where to look for issues. Also when I pull the hazards switch my front hazards come on but not my back

[kramttocs]

So I replaced the turn signal switch

Both turn signals now work. But still now brake lights. And yes I do have a multi meter just don’t know what and where to look for issues. Also when I pull the hazards switch my front hazards come on but not my back

So:

1. All 4 turns signals work

2. Hazards only work in the front

3. Brake lights don't work

Seems odd that the hazard isn't working in the rear but the rear turn signals are. Trying to make sense of that.

For a simple test to rule it out, first check for voltage on the stop lamp switch. One terminal (Light Green) should get voltage when you press on the pedal. The other, LG/R (Light Green with Red hash marks), should have constant 12v.

For reference, here is the circuit from the 85 evtm

[ArdWrknTrk]

So:

1. All 4 turns signals work

2. Hazards only work in the front

3. Brake lights don't work

Seems odd that the hazard isn't working in the rear but the rear turn signals are. Trying to make sense of that.

For a simple test to rule it out, first check for voltage on the stop lamp switch. One terminal (Light Green) should get voltage when you press on the pedal. The other, LG/R (Light Green with Red hash marks), should have constant 12v.

For reference, here is the circuit from the 85 evtm

Do the hazards and brakes work on the feed side of the circuit and the turns work on the ground?

I'm not that familiar with that schematic but you were deep in it last week Jonathan.

[kramttocs]

Do the hazards and brakes work on the feed side of the circuit and the turns work on the ground?

I'm not that familiar with that schematic but you were deep in it last week Jonathan.

If the hazard switch hadn't just been replaced I'd put my money on it. The brake lights not working is one thing but I just can't come up with how the rear turn signals work but the rear hazards don't aside from a defective hazard switch.

If it was in front of me, I'd start probing the steering column connectors and tracking where the voltage is and isn't.

[ArdWrknTrk]

If the hazard switch hadn't just been replaced I'd put my money on it. The brake lights not working is one thing but I just can't come up with how the rear turn signals work but the rear hazards don't aside from a defective hazard switch.

If it was in front of me, I'd start probing the steering column connectors and tracking where the voltage is and isn't.

The only thing I see common to Hazards & Stop rear, and not the turn signals is the 511 wire associated with the speed control on the right of the diagram.

Let me have a deeper look at this schematic, and see if I can be the electron..