Brake Light and Horn not working

[Brendanchambers]

Hello All

69 383 RR,
i'm no auto electrician however i'm a fan of trying to fix little issues myself to save a dollar or two.

My rear indicator works, so I'm guessing that means the rear brake lights work and there's something wrong with the switch or wire or connection or something....

the horn doesnt work however i connected it up directly to the battery (probably not the safest thing to do...my bad) and it worked, when i push the horn you can hear a relay or something activating under the hood......


so, does anyone have any ideas where to start?, i have access to a huge range of FLuke multimeters as we stock and sell them at work, so shouldnt be any issues to get any piece of test equipment for "demo" purposes...

please let me know what you think.

 

[Mike Szadaj]

First place to start is with the fuses there is a fuse marked for the rear lights check that

 

[Brendanchambers]

First place to start is with the fuses there is a fuse marked for the rear lights check that

ok, would that affect the indicators though?

 

[Mike Szadaj]

I don’t understand what you are referring to when you say rear indicator.

 

[Mike Szadaj]

In the title of the post you say brake light not working. But then in the post you say you assume that the brake lights are working. Put something like a piece of wood between the brake pedal and the seat and then go in the back of the car to see if the brake lights are working if you don’t have someone to Help you.
By rear indicator do you mean turn signal?

 

[Brendanchambers]

In the title of the post you say brake light not working. But then in the post you say you assume that the brake lights are working. Put something like a piece of wood between the brake pedal and the seat and then go in the back of the car to see if the brake lights are working if you don’t have someone to Help you.
By rear indicator do you mean turn signal?

yes turn signal

 

[Mike Szadaj]

OK, now we need to know if the brake lights are working or not. The turn signal circuit is separate from the brake light circuit. If you think about it, the brake lights work anytime key in or not. The turn signals will Only work with the key in the on position.

 

[R413]

Brake and turn are the same wires from the Turn signal switch to the bulbs. So if the turn signals work on both rears then the wiring and bulbs are good.

Now go to the brake pedal switch, 2 connections, pink is power and the white sends the signal to the TS switch. If you step on the pedal and power is on that white wire going into the TS switch then the TS switch is bad.

 

[Mike Szadaj]

so, does anyone have any ideas where to start?

Going back to what I said before, in the title it says brake lights do not work. Later on you say you think they work. What are the facts here? Looking at the back of the car do the brake lights work? Do the left and right turn signals work? Do the running lights work?

 

[Mike Szadaj]

the horn doesnt work however i connected it up directly to the battery (probably not the safest thing to do...my bad) and it worked, when i push the horn you can hear a relay or something activating under the hood.......

You testing the horn was a very good idea. The fact that we now know that the horn works is the first step in diagnosing your problem. If your analysis about the sound you are hearing is correct, that narrows down the problem significantly. Either the constant power source to the relay has been interrupted, or the relay itself, even though you are hearing that clicking noise from it, is not making electrical contact and sending voltage to the horns. A meter or a 12 V test light, either one, would be the best equipment needed to diagnose the problem. We Would need to know if you have one or the other Or both on hand.

 

[Brendanchambers]

Going back to what I said before, in the title it says brake lights do not work. Later on you say you think they work. What are the facts here? Looking at the back of the car do the brake lights work? Do the left and right turn signals work? Do the running lights work?

sorry, probably not explaining myself the best, the turn signals work, and i thought they use the same bulb etc, so i figured its not the actual light itself....when i push the brakes, the light doesnt come on....so its something wrong with the circuit or the switch...there's a mass of wires under the dash and i'm really not too sure where to start......trust this makes sense...post #8 probably explains it better....

 

[Brendanchambers]

You testing the horn was a very good idea. The fact that we now know that the horn works is the first step in diagnosing your problem. If your analysis about the sound you are hearing is correct, that narrows down the problem significantly. Either the constant power source to the relay has been interrupted, or the relay itself, even though you are hearing that clicking noise from it, is not making electrical contact and sending voltage to the horns. A meter or a 12 V test light, either one, would be the best equipment needed to diagnose the problem. We Would need to know if you have one or the other Or both on hand.

thanks. i have access to both a meter and test light pen (if thats what you mean)

 

[drhill]

I had a similar problem where the turn signals worked but the left brake light did not. I found that the turn signal switch was the problem.

 

[Mike Szadaj]

The very first thing you need to do is check the fuse. If that fuse is blown and everything else is in working order, the turn signals will work but the brake lights will not. Check that fuse.

 

[Mike Szadaj]

ok, would that affect the indicators though?

You asked the question earlier but I did not reply. Sorry about that

 

[Brendanchambers]

The very first thing you need to do is check the fuse. If that fuse is blown and everything else is in working order, the turn signals will work but the brake lights will not. Check that fuse.

ok, good idea..will check that when i get home and then go from there..

 

[Mike Szadaj]

If your fuse box is the same as my 68 Coronet, which I’m pretty sure it is, it will be the second fuse In from the passenger side of the fuse box.

 

[Mike Szadaj]

If it is blown, it is a 20 amp fuse

 

[Brendanchambers]

cool, thanks for your help

 

[Mike Szadaj]

View attachment 1064068
In the upper left-hand corner of the wiring diagram are the horns and horn relay. As you can see all wires have an alpha numeric designation. The first part is the actual name of the wire such as H2 and H1. The second set of numbers after The dash is the gauge of the wire. The last letters after the second Dash are the color of the wire as shown in the color code at the bottom right hand of the diagram. If you use your test light With one end of the test light attached to a good ground in the engine bay, and the other side of the test light touching wire H1-16-V, the test light should light up. That is a violet colored wire. When the test light is touching the H3-18-BK* wire, The test light should only be on when the horn button is pushed. That is a black wire with a white stripe. When the test light is touching the H2-16-DGN wire, it should light up and the horn should blow when the horn button is pushed. That is a green wire. If there is not a constant 12 V on the violet wire, somewhere it is broken or it is not attached to the starter relay as shown in the diagram, Or the connectors at one end or the other are tarnished in such a way that electrical contact is not being made. If there is not 12 V on the black wire when the horn button is pushed then there is a problem with that wire or the horn button in the steering wheel. If there is 12 V on the violet wire and 12 V on the black wire when the horn button is pushed, but there is 0 V on the green wire, the relay is bad. If there is 12 V on the green wire at the relay, but no horn, the green wire going from the relay to the horns is bad. If you would end up having to replace some wires, you would use those gauge numbers to make sure your replacement wire isn’t smaller than it should be.

PS, The wiring diagram is for a 68, but should be the same for a 69.