Brake controllers

Submitted: Thursday, May 12, 2005 at 09:06
ThreadID: 22921 Views:1702 Replies:5 FollowUps:7
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OK, I was servicing the brakes on the camper trailer over the weekend. One thing that really stumped me was that when I checked for power at the towbar plug (on the car) the blue brake cable and white earth showed 12.5 volts when there was no brake pedal depression.

The brakes worked fine but my curiousity was aroused on how does the brake controller work? It seemed to be always powered.

Can someone put me out of my misery and tell me how this is so?

Kind regards

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Reply By: Member - Troopytrek - Thursday, May 12, 2005 at 09:50

Thursday, May 12, 2005 at 09:50
G'Day Beatit,
Not entirely sure but I came across the same thing on the inernal dash fan set up in a car I was working on once, how it worked was instead of connecting power when the switch was activated it actually connected earth and the fan speeds [or voltage] was controlled by the earth set up. maybe this is similar to the way your brakes work.

Troopytrek!!!

P.S. We are just sorting out final bits& pieces before our trip [about 6 weeks left] how are you going with your preparations? and are you looking forward as much as we are?
AnswerID: 110960

Follow Up By: Member - Beatit (QLD) - Thursday, May 12, 2005 at 10:00

Thursday, May 12, 2005 at 10:00
G'day,

It has me stumped but i suspect your right.

Yeah, our crew are chewing at the bit - we have just over 8 weeks to go. I certainly hope our level of preparation will reflect in reduced issues on the trip!

There always seems to be something to do for the trip, been acumulating fishing gear for this trip over the last 2 years and started packing only to realise that I've probably ended up with more gear than clothes - so I'm guessing a great trip in store. By the way do you have a good answer to "why do you need 9 fishing rods"? (my wife is only an occasional fisher), tried the "why do you need 9 pairs of shoes" line without much success!

Kind regards
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FollowupID: 367377

Follow Up By: Member - Beatit (QLD) - Thursday, May 12, 2005 at 10:10

Thursday, May 12, 2005 at 10:10
PS spending so much time thinking about it and getting ready that it seems I'm already on holidays!
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FollowupID: 367379

Follow Up By: Member - Troopytrek - Thursday, May 12, 2005 at 10:29

Thursday, May 12, 2005 at 10:29
Beatit,
As for the question. I have learnt that you will never win an arguement when it is with a politician[ Minister for war & finance]. AS for the thinking about the "TRIP" I'm trying to rap up a workshop and having a great deal of trouble because my mind is to focused on going away and besides that I would rather be reading this forum and preparing than working!!!

Troopytrek!!!!

P.S. I'm sure you have heard travellers saying "Happy kids Happy holiday" well I am not sure whether there needs to be another one "happy wife Happy holiday" or [tongue in cheek awaiting a back hand] does the wife come under the first saying. Ouch as I expected went down like a fart in rectory.
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FollowupID: 367382

Reply By: Paul from Ozroamer Camper Trailers (Hire & Sales) - Thursday, May 12, 2005 at 10:25

Thursday, May 12, 2005 at 10:25
Troopy
I have a trailer getting an onboard brake controller installed today. when I pick it up from the AutoElect today I will find out for you.
AnswerID: 110968

Follow Up By: Paul from Ozroamer Camper Trailers (Hire & Sales) - Thursday, May 12, 2005 at 10:32

Thursday, May 12, 2005 at 10:32
I mean Beatit
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FollowupID: 367383

Follow Up By: Member - Beatit (QLD) - Thursday, May 12, 2005 at 11:31

Thursday, May 12, 2005 at 11:31
Hi Paul, I thought that's what you meant and thanks. Look forward to the info.

Kind regards
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FollowupID: 367391

Follow Up By: Paul from Ozroamer Camper Trailers (Hire & Sales) - Thursday, May 12, 2005 at 16:40

Thursday, May 12, 2005 at 16:40
My man has spoken -
Some controllers will show a reading with a meter but this will fade under load. In his words this is "unusable power". The brake peddle needs to be engaged to get power!!

Means nothen to me!!!!
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FollowupID: 367435

Follow Up By: Member - Beatit (QLD) - Friday, May 13, 2005 at 10:41

Friday, May 13, 2005 at 10:41
Paul,

Thanks for the feedback, still as clear as mud to me as well. Mine showed a full 12.5 volts in the trailer plug (car section and disconnected) with no pedal depressed.

Kind regards
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FollowupID: 367568

Reply By: Member - Banjo (SA) - Thursday, May 12, 2005 at 18:03

Thursday, May 12, 2005 at 18:03
Just checked my Tekonsha Prodigy set up - wired in by a pro supplier - no voltage there at rest with ignition on - have to push the manual control lever over to get any voltage available. Mind you, it could be different once the trailer -plug is popped in - with a circuit made, the Prodigy might go into another mode ... electronics might as well be magic to me !
AnswerID: 111031

Reply By: Member - Stillthinkinaboutit - Thursday, May 12, 2005 at 18:38

Thursday, May 12, 2005 at 18:38
Some controllers have an indicator LED to show that a complete circuit is present. The LED lights when you connect the trailer to the vehicle. A very small current is always passing through the coils of the brake magnets, the LED is iluminated.
The voltage you are measuring would be normal with a controller like a Tekonsha Sentinel.
The sentinel has a green LED to indicate a functional brake circuit.
AnswerID: 111034

Reply By: MrBitchi - Friday, May 13, 2005 at 10:58

Friday, May 13, 2005 at 10:58
Most switches on a car switch the Earth side, not the Power side. Less likelyhood of sparks....
With the brake controller it would depend on how the sparkie wired it. It can work either way.

Cheers, John.
AnswerID: 111153

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