Hazard and Brake Lights Switch Wiring Diagram ? - Brake Controller

[eXodus]

I'm looking for a wiring Diagram of the Hazard Light Switch and the Stoplight Switch. The previous owner wired in a Brake Controller - which works perfectly fine - but activates the trailer brakes when you turn on the hazard switch.


This is my pedal switch

so I have to trace some wires and figure out why it's doing that and get rid of this feature.  I looked through the diagram in the member section but no luck in finding those switches of not understanding the acronyms

[Eyez Open]

So your brakes are pulsating or continuous? Makes a difference.

[eXodus]

the brakes are pulsing with the lights.

So there must be somehow power from the hazard switch flowing where the brake controller ties into Stop light switch.

Maybe a Diode would fix it, but I don't want to cut cables and put in random diodes

[Eyez Open]

the brakes are pulsing with the lights.

So there must be somehow power from the hazard switch flowing where the brake controller ties into Stop light switch.

Maybe a Diode would fix it, but I don't want to cut cables and put in random diodes

https://www.etrailer.com/question-30268.html

[DaveVA78Chieftain]

Solution for Trailer Brakes that Apply When Hazards are On

[eXodus]

Thanks everyone,

that already helps a little, but my electrical engineering mindset tells me there must be a better way then a $35 diode device.

I need the diagrams of the brake switch.  There are at least 2 circuits routing through P30 brake light switch - what is the the other one for?  On activates the brake light - but what is the other one doing?  Is that unlocking the column shifter?  Every time I press the brake I hear something clicking somewhere in or close to the steering column.

You can not shift into gear - when you don't press the brake, just would need to know if I can wire into the other half of the switch to get a signal to the brake controller. 

Wiring to the brake lights is just a half measure - yes it works - but as soon you burn out a both brake light - the brake controller also stops working - not a good solution.

[DaveVA78Chieftain]

Not sure if this will help or not but here is the Directional/Hazard circuit diagram for a 1999-2003 P-32 with 8.1L

Sorry about image quality. If you save it to your harddrive then you can blow it up a little for a better presentation.

[eXodus]

Yes Dave  , that already gives me some wire colors to trace.

Do you by chance have more of those diagrams?  The 8.1L wiring is pretty much identical from what I got in mine.

I don't know which sub system, could be transmission, hydro boost brake, or shifter - something is hooked up to the brake pedal switch.

[DaveVA78Chieftain]

Workhorse Technical Info

[Mlw]

Wiring to the brake lights is just a half measure - yes it works - but as soon you burn out a both brake light - the brake controller also stops working - not a good solution.

Are you not thinking too difficult Exodus?

As you are telling the system works right now, I'm very suspicious your brake-controller is connected in series on the ground wire connection from you brake-lights. so power source - brake light bulb(s), brake controller – ground. This would explain the brake-controller not working when both brake light bulbs are out and this means this system is built in as an add-on. It surely is not original. Like you say, brakes not working because the light bulbs are out is not a good idea, not to mention when the ground connection goes bad and for example the turn signals start working via your brake-controller.

If you know where the controller is, i would retrace you wires and my guess is that the PO spliced it into the ground wire/ connection of your rear (brake) lights or they made a double connection behind one of the brake lights on the ground connection in your light fixture. If the latter is the case you can fix this to connect the wire to the brake-controller to the positive connection of the light-bulb, but is not something I would recommend as it controls your trailer brakes and your safety is involved. Now, to be honest,  I'm not really familiar with these brake controller systems but it sound simple. As soon as you press the brake pedal the controller gets a signal and makes the brakes of the trailer work so only an on/off system. Did I understand this right?

As I think this is a safety feature I would make sure the connection is absolutely dry with minimum chance of corrosion so inside the RV at the brake light switch. Yes, this means running wires from the front to the back of you RV, but a small price to pay for your safety I guess?

[eXodus]

Wiring to the brake lights is just a half measure - yes it works - but as soon you burn out a both brake light - the brake controller also stops working - not a good solution.

Are you not thinking too difficult Exodus?

German Electrical Engineer - thinking difficult is my specialty

The brake controller is under the dash - I can clearly see it and like I said - it works fine during normal operations.

1. The Hazard light switch is activating the brakes
2. The light bulbs are somehow influencing the controller as well

Probably have to do some crawling and chasing all those grounds and wires... an open ground or bad positive for the brake controller would not be good and really a safety issue.

But thanks to Dave I got some more understanding how the Hazard switch works now and can see if I can can put a diode somewhere to avoid that.

[eXodus]

I'm reading through Workhorse Wiring Diagrams and found something interesting:



So apparently the second contact of the Brake Light switch is a NC (normally closed)  and is being opened when you press the pedal. This is used to activate the ABS module what I gather.

A NC switch is better from a safety standpoint - since closing contacts could fail much easier - while you can check for continuity. Opening contacts is safer.

Not sure how to use this information my problem, but I thought I share it

[eXodus]

Found something better, there is a provision in the switch which is doing all the stuff in the dashboard - like turning of cruise control and unlocking the steering column when pressing the brake pedal.

That's on the white wire - while the brake lights are on the blue wire.

Most important - both are only connected when you are on the brake pedal - so the hazard should not influence the the brake signal.

So lets go out to the RV and move the brake controller signal from the blue to the white wire and see what happens.

[DaveVA78Chieftain]

Looking closer at the drawing I provided I can see what is happening.  The Brake Light signal (circuit 17) is injected into the turn signal switch at the center right of the switch.  Do to the wiring of the circuit, when the Hazard switch is engaged that hazard light signal is also being feed back down the brake light signal circuit.  Only way to prevent this from happening is to have a diode in the brake light circuit 17 path such that it prevents the hazard light signal from being feed back down to the brake light switch

TS Switch ----- Diode ----- BL Swtich
                                      |
                                      |
                            Trailer Brake Controller

However, you could also just hook the brake controller to the third Brake Light  circuit 20 as you stated in post 12 and have the Brake Light switch isolate the Trailer Brake Controller.  (I know better than to not read all the posts )
Note: only move the added Trailer Brake wire to circuit 20. Do not change the original Blue / White wiring as that will move the issue over to the third brake light.

[eXodus]

So I did some crawling and measuring.

The brake light switch 3 pin port none of those are connected when pedal is resting. NO  And there is continuity between all 3 when depressed.

The two pin is a NC so it's closed when the pedal is resting and open when pressed.

The previous owner connected the controller to the white wire of the 3 pin. Not on the blue one like i would have expected. 


Dave connection to the 2 pin 3rd brake light does not work at the switch directly. Since it's 12V always positive. When you press the pedal it gets pulled to ground.  So just opposite what the brake control is expecting.

But there are some relays clicking when I unplug the 2 pin connector.  Just have to trace which are doing the clicking and find an output which gets positive when pushing the pedal.

[Mlw]

German Electrical Engineer - thinking difficult is my specialty

    

Yes and expert in overengineering too I guess???    

Don't get me wrong, I love the Germans for it and the reason why I drive a BMW E39, 24 years old and still starting and running like it came out of the factory yesterday  but even in Germany punktlichkeit and overengineering is dissapearing it's such a shame.

So I'm not going to tell you what to do then, because you'll know better what to do then i am.

I should have looked at your avatar info to to see you have a 2003 model, so full of digital gadgets. I have one from the seventees where it's all pretty straight forward and everything still can be fixed by thinking logical.

[DaveVA78Chieftain]

All I can say is if the original circuit is like the ones in the drawings, then at the Brake Light switch the three post portion should be the portion your looking for with the following three wires in that three post connector:

Orange (circuit 140) from fuse
Blue (Circuit 20) for 3rd brake light (isolated from hazard switch when brake is resting)
White (Circuit 17) for turn signal switch, cruise control, etc.

Looking at several years/models, they all seem to use the same concept.

Good luck

[eXodus]

All I can say is if the original circuit is like the ones in the drawings, then at the Brake Light switch the three post portion should be the portion your looking for with the following three wires in that three post connector:

Orange (circuit 140) from fuse
Blue (Circuit 20) for 3rd brake light (isolated from hazard switch when brake is resting)
White (Circuit 17) for turn signal switch, cruise control, etc.

I've  moved the brake controller from the White to the Blue wire at Paddle switch and it seems like to behave like you are describing. No Pulsing on Blue for the 3rd Brake light (I don't have one - anyhow)

So there was simple solution for the problem