Brake lights and hazards not working- replaced turn signal switch did not fix it

[gws34]

I have tried to read all of the posts with this subject but still can not find the fix.

This is my daily driver 1975 bronco. The other day I discovered as i was backing into the garage that I had no brake lights. I do not know when they went out.

Tried to chase down the problem and thought since everyone says it is usually the turn signal switch i just replaced that, did not fix it.

Here is what I have found and tried so far....

I have a painless wiring harness that I installed 10 or so years ago. I replace the turn signal switch and harness today.
I have put a volt meter on the brake light switch with nothing connected to it and it takes very little pressure on the pedal to get it to show continuity- so that seems to work.

I have power going into the brake switch from the one side, when i depress the pedal with the switch functioning the voltage drops to 0. When I pull the wires from the brake light switch and connect them together it does the same thing. (This seems to be the key to the problem, but I am not sure why?)

All of the directionals work, all of the running lights and headlights work.

The hazard lights don't work

I tried switching the directional flasher with the hazard flasher an the both flashers work in the directional plug.

When i disconnect the steering column harness from the dash harness, when i depress the brake pedal I have power at the plug that lines op with the red and black wire in the steering column harness as it should.

Since the directionals and running lights work then all the wiring to the back of the bronco should be good, correct?

What else can I check? I have had to borrow my wife's car and drop her off at work for the last 2 days and she is getting tired of this, please help/advise what should be the problem.

Thanks
Glen

 

[gws34]

Also I checked the fuses and they are all good.
Steering column hazard switch.
Checked to make sure the tail light lamps were all good.

So tired........... can not think of what else I have checked.

 

[Broncobowsher]

The voltage dropping to zero going into the brake light switch (when activated to turn the lights on) is the problem.
I don't know the painless harness good enough, is there a brake light fuse? Without removing it, put the meter on it (both sides) and test again.

 

[ba123]

I would think you have a short somewhere.

Pull your headlight switch out of the dash and then try the test at the brake light switch again.

There are only so many places the problem could be.

 

[jamesroney]

I would think you have a short somewhere.

Pull your headlight switch out of the dash and then try the test at the brake light switch again.

There are only so many places the problem could be.

Short is such a funny word. It can mean so many things, and yet it is only 5 letters. (kinda Short!!!)

But alas, no. Not a short in the traditional sense...which is a low impedance fault to ground. Nor is it a short in the more general sense...which is a fault across circuits.

Based on his description, what he has is a high resistance open in the supply voltage between the battery and the brake light switch. I suspect that he is using a digital Volt meter to measure his circuits. A digital or high impedance VOM has no business in an auto repair shop. A "True RMS" multimeter is the worst tool ever unleashed on the unsuspecting auto enthusiast.

What he needs is an analog multimeter with some inherent resistance, like a Simpson 260 VOM, or he needs an incandescent test light. If he does not have one, a standard automotive headlight makes a great resistive load and voltage indicator. The 6014 Sealed hi beam is good for about 5 amps. Tie one side to ground, and use the other terminal to probe. Start at the battery, and LOOK at the bulb. It will glow bright and warm! That is your calibration reference.

If he measures the voltage when loaded using the 6014 bulb with one side to ground, and one side to the source...it will either illuminate brightly, or it will illuminate dimly, or it won't illuminate at all. I suspect if he applies the bulb at the brake light switch...it will not illuminate, and the voltage measurement will drop to 0 VDC. That's because there is a fuse or circuit breaker or wire that is "mostly open" but has a tiny bit of continuity. So if you measure it unloaded, it gives you 12 VDC, but as soon as you put any kind of load on it...it goes open. It is also possible that he is back feeding the brake light switch from one of the 1157 dual element bulbs with a bad ground, or thru a floating instrument cluster. But none of that matters. As soon as he loads the circuit with the headlamp, everything will be answered.

Once he takes a legit measurement...then he will know that his supply circuit is lacking in ampacity. Finding the loose wire, bad connection, or faulty crimp will take more diagnosis. His problem is likely that he has two unrelated problems. A floating ground, AND an interrupted supply. The combination will give confusing diagnostics. So the answer is to isolate and test. Or just use a better tool.

I don't usually try to explain to people how to troubleshoot electrical problems, because you can make a lot of trouble in a hurry. But the stop light circuit in an EB should be pretty uncomplicated.

 

[Lawndart]

Auto transmission?
Isn't the neutral safety switch part of the backup light circuit?

 

[DirtDonk]

In the original setup, brake light power came directly from the headlight switch. I don’t remember where Painless gets it, because they do use a fuse in their panel, I believe. Where Ford did not.
So it may be completely unrelated to the headlight switch in this scenario.
Proceed as suggested. But first you might call Painless just to verify. Maybe even just jiggle some wires at the fuse panel! See if anything changes.

Was the body recently painted? If so, make sure the mounting screws and tail light buckets are making good contact with the body and providing a good solid ground path.
One possible clue, to this non-expert, is that the turn signals work, but the brakes and hazards don’t. The brakes and hazards use both tail lamps, so maybe there is a lack of a good path to ground in one or both tail lamps.
Enough of a connection to service the individual filaments, but not enough for both.
There is still a fault in the brake light circuit, but the hazards not working could be a separate fault.
Or could just be too bad turn signal switches in a row!

Yes, the backup lamps go through the neutral safety switch. But I don’t believe the OP mentioned anything about the backup lamps not working.
Just the hazards and brakes.

 

[Broncobowsher]

Short is such a funny word. It can mean so many things, and yet it is only 5 letters. (kinda Short!!!)

But alas, no. Not a short in the traditional sense...which is a low impedance fault to ground. Nor is it a short in the more general sense...which is a fault across circuits.

Based on his description, what he has is a high resistance open in the supply voltage between the battery and the brake light switch. I suspect that he is using a digital Volt meter to measure his circuits. A digital or high impedance VOM has no business in an auto repair shop. A "True RMS" multimeter is the worst tool ever unleashed on the unsuspecting auto enthusiast.

What he needs is an analog multimeter with some inherent resistance, like a Simpson 260 VOM, or he needs an incandescent test light. If he does not have one, a standard automotive headlight makes a great resistive load and voltage indicator. The 6014 Sealed hi beam is good for about 5 amps. Tie one side to ground, and use the other terminal to probe. Start at the battery, and LOOK at the bulb. It will glow bright and warm! That is your calibration reference.

If he measures the voltage when loaded using the 6014 bulb with one side to ground, and one side to the source...it will either illuminate brightly, or it will illuminate dimly, or it won't illuminate at all. I suspect if he applies the bulb at the brake light switch...it will not illuminate, and the voltage measurement will drop to 0 VDC. That's because there is a fuse or circuit breaker or wire that is "mostly open" but has a tiny bit of continuity. So if you measure it unloaded, it gives you 12 VDC, but as soon as you put any kind of load on it...it goes open. It is also possible that he is back feeding the brake light switch from one of the 1157 dual element bulbs with a bad ground, or thru a floating instrument cluster. But none of that matters. As soon as he loads the circuit with the headlamp, everything will be answered.

Once he takes a legit measurement...then he will know that his supply circuit is lacking in ampacity. Finding the loose wire, bad connection, or faulty crimp will take more diagnosis. His problem is likely that he has two unrelated problems. A floating ground, AND an interrupted supply. The combination will give confusing diagnostics. So the answer is to isolate and test. Or just use a better tool.

I don't usually try to explain to people how to troubleshoot electrical problems, because you can make a lot of trouble in a hurry. But the stop light circuit in an EB should be pretty uncomplicated.

Correct. Not a short. High resistance. Barely touching connection. Why I speced to not touch the fuse when testing it. Corrosion or a cracked fuse can cause this. Simply pulling it can push the contacts together and you loose the problem, for a little bit. It will come back, usually at the worst time.

I find a incandescent light bulb to be more useful than a meter when chasing most electrical issues (electronic is different) Basic automotive electrical, the brightness of an incandescent lightbulb and the load of that tiny light bulb are extremely useful. You don't need exact values with most automotive electrical, a variable brightness lightbulb is a great tool. I'll even use it backwards. Put the aligator clip on the positive terminal and poke around looking for grounds.

 

[gws34]

It is a manual not automatic.

I will continue to try to chase these options down.

thanks, I will post an update tonight after I try to solve this again.

 

[gws34]

Yes the painless harness has the power come from a fuse not the headlight switch like to original wiring.

 

[gws34]

I have both digital and analog testers, and a test light. I will continue to test and check all of the grounds.

No the bronco has not been painted, someday that would be nice, but I have the original paint with the nice patina and worn out color.

I had replaced the fuse with no change, but again I have been working on this till late at night in my garage after working a 10 hour day and getting the kids fed and homework done with them and get them to bed so exhaustion does make it harder to think straight and solve the problem. BUT yes I agree the brake circuit is such a simple one that is why it is frustrating me to get it fixed.

thanks
Glen

 

[ba123]

if you jump the brake wire that goes from the brake light switch (another 12v source) to the brake lights, do they turn on?

Meaning, try a different power source before you go troubleshooting your power source. Maybe there's a problem on the light side, at least eliminate that.

Then, if that works, try jumping the hot side of the brake light switch to a different source.

 

[ssray]

I think they’ve got you on the right track. I took a look at the manual online and saw that the circuit is on the hot side of the fuse. block as you mention now and DD suggested. There is also a connection to the hazard flasher in there somewhere from that hot feed. Possibly a connection point that could be causing problems?

 

[DirtDonk]

It’s always a finicky hunt in this case. The 75 has its hazard switch integrated into the turn signal switch.
And now there have been two turn signal switches with the same problem.
The problem here is, it’s not impossible for there to have been too bad turn signal switches!

 

[ssray]

It’s always a finicky hunt in this case. The 75 has its hazard switch integrated into the turn signal switch.
And now there have been two turn signal switches with the same problem.
The problem here is, it’s not impossible for there to have been too bad turn signal switches!

I just ran into something along those lines…that other competitor though. Turn signals and Hazards would quit. Wiggling the flasher module would get it back working. Picked up one at NAPA to see if that was the problem or if it was a connector problem. Put it in, it buzzed a bit and quit and now nothings working. Blew a fuse. Replaced the fuse, put the original flasher back and alls working again, just intermittent as before. Searching a J### forum found people having that happen as well. Pin outs were Ok so ??? It’s a 2004 and Mopar doesn’t even have the flasher available so you’re stuck with after market. Grrrr

 

[gws34]

I was pulling wires out from the dash to check things and then found the back passenger tail light/brake light was on.

Now a painless wiring connection question... at the taillight connector there is a ground wire on the one side and on the other side of the connection is a wire labeled lamp ground as a wire coming out of the plug on the other side of the connector. I have them connected to the same ground screw but should the one that says lamp ground should that be connected to the taillight housing?

 

[DirtDonk]

I was pulling wires out from the dash to check things and then found the back passenger tail light/brake light was on.

What was the progression of this find?
How did you find that the passenger light was on, while you were under the dash? And which was it? Tail lamp, or brake lamp?

Now a painless wiring connection question... at the taillight connector there is a ground wire on the one side and on the other side of the connection is a wire labeled lamp ground as a wire coming out of the plug on the other side of the connector. I have them connected to the same ground screw but should the one that says lamp ground should that be connected to the taillight housing?

Got a pic you can show us? The taillight connector back at the tail lights? Or up by the firewall? Or is there one at the firewall with the Painless harness? I don't remember, but I know some of them have a separate tail section connector right after the wires pass through the firewall.
Which side has the ground wire? Chassis or lamp?
Which side has the other wire? Chassis or lamp?

Normally you can put two lamp grounds on a common point of metal. But if one is meant for connecting to the housing, to ensure it's grounded, then it would be good to use it thusly. I don't have the current Painless instructions in front of me (and don't really want to wade through them at the moment either!) and don't remember how they wire the tail section.
That's why a pic would be helpful in this situation.

Thanks

paul

 

[gws34]

It looks like to me the ground lamp wire would be maybe for a fiberglass body to ground the taillamps? maybe.

Update I have the passengers side working now, tomorrow will have to be solving the driver side.

I pulled all of the non connected wire out from under the dash and maybe one of them was "shorting " it out, still not 100 percent sure.


Thanks
Glen

 

[gws34]

thanks DirtDonk, I know you always have some very helpful info. I can send a pic tomorrow. Got to go to sleep now.

Thank you everyone, I can always rely on this forum to have solutions for our wonderful Broncos.

 

[gws34]

The brake light was the one that was on, again so tired that it took me 10 minutes to realize it was on because I had previously connected to two wire from the brake switch together to test the wires, so at that point (when i noticed it was fixed I had been pulling the loose wire and stuff from under the dash so it must of cleared up the short that was in the dash and the light turned on.

driver side still an issue but hopefully I will find that tomorrow and clean up under the dash and get it put back together without creating a new short.

Thanks