dougrainer
Carrolton, Texas
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JRscooby wrote:Learjet wrote:Clamp on DC amp meter would be a better test.
I have seen LEO use the compass to check brakes in a roadside safety check. To tell you anything you need to hold compass near hub, but not so close that needed responds to the metal, apply brake, watch for needle to respond. The most it can tell you is there is power to magnet(s)
Yes, the AMP meter would be better, but bet a larger percentage of people have a compass.
dougrainer wrote:ALL the Breakaway switch does when activated is put FULL 12 volts to the Trailer brakes. AS long as you have a GOOD Trailer battery. An easy test is to simply connect the Trailer to your Truck. PULL the Break away lanyard loose
BAD ADVISE! Unless you tell them to disconnect the light cord. There is a chance the brake controller will be damaged by power back-feeding if the pin is pulled while connected
Quote:and then attempt to drive forward(NO truck brakes at all). Have someone WATCH all 4 wheels and tires ALL should be locked up and drag. It is best to do this on dirt or gravel lot. Concrete will not be a real problem for this test, but it is easier to drag on Dirt or Gravel. This will tell you that the Shoes and magnets are in working order. If you have a Wheel not locking up you then test the 2 wires going to that Brake and see if you have Ground and 12 volts. If NOT, then find where the open circuit is by the axles. If you DO have 12 volts then the Brake shoes are probably not adjusted correctly. Doug
I have never in 42 years had a Back feed. BUT you are correct. To do the test with more safety, disconnect the 7 way plug and then pull the lanyard. Doug
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msmith1.wa
Tacoma, WA
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freewayrandy wrote:I just had to have all new brakes put on my trailer at about 13K miles. 3 of the 4 were metal to metal. Usually run the controller 5/6. Has anyone heard of a brake test using a compass? It says with the brakeaway pin in (no voltage to electromagnets) put a compass up to the hubs. Compass should point north. Pull the pin and compass should point to the brakes. Well, With the pin in, I have 3 that the compass is pointing to the brakes! For the heck of it, I ordered a new breakaway switch. What else could possibly be an issue?
Based on your description three appear to work properly and one is not. I don't think the problem is the break away switch because three work. For some reason one magnet is not working. Either the magnet is bad or there is a bad connection in the wires.
The compass is just detecting the magnetic field created when the breaks are applied. Sometimes a hum can be heard from the magnets.
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msmith1.wa
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The instructions for Prodigy break controllers have a warning that pulling the pin when plugged in may destroy the controller.
* This post was
edited 03/05/22 07:57am by an administrator/moderator *
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ssthrd
Vancouver Island
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Had maybe double that on my last TT and still had some life left. Curious.......are you a left foot braker?
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valhalla360
No paticular place.
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dougrainer wrote:
I have never in 42 years had a Back feed. BUT you are correct. To do the test with more safety, disconnect the 7 way plug and then pull the lanyard. Doug
Even simpler, just crank the controller to max and use the lever to activate the trailer brakes while going forward. (Remember to return it to normal setting before travel)
We do this every time when leaving a site (minus the max setting). If I don't feel the brakes grab, I can stop and address the situation.
But really, the OP knows there is a issue, so getting the multimeter out makes far more sense, so he can track down the real problem.
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JIMNLIN
Oklahoma
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12 v can show with a couple of strands from a cut wire...however to get enough amps to the magnet a few strands won't work for full braking performance.
Thats why a check with a amp meter tells the tale.
I've found those clam shell connectors over time loose good connectivity over a short period.
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bucky
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bgum wrote:We usually run on 3-4 with prodigy p3. Boost set at 1-2. You may be running a little too high. Is your 5th wheel pushing the truck when braking?
The trailer would not be pushing the tow vehicle in this scenario. It would be the opposite.
As to pulling the safety switch and worrying about the controller just get somebody to push the brake pedal for you while hooked up.
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JRscooby
Indepmo
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dougrainer wrote:
I have never in 42 years had a Back feed. BUT you are correct. To do the test with more safety, disconnect the 7 way plug and then pull the lanyard. Doug
Well a guy I worked with had E-brakes on half the axles on his short end-dump. LEO, doing a "safety inspection" thought he was checking for water in a air tank, pulled a cable. The driver standing next to trailer saw the smoke. When they weighed the trailer, it was overweight because the brakes did not work on 2 of the axles. I did not have a trailer behind my old F500, so I pulled my controller, so he could get down the road.
Like somebody else said, the instructions warn against pulling pin while the cord is attached.
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schlep1967
Harrisburg, PA
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Come on people. READ THE ORIGINAL POST.
His brakes wore out prematurely. That doesn't happen if his brakes don't work.
It happens when they are engaged and shouldn't be.
Most likely case would be driving with a foot resting on the brake.
After that I would look toward a short on the tow vehicle providing voltage to the brake circuit. Test at the trucks seven pin plug.
If it was the emergency breakaway the battery on the camper would be dead unless it is plugged in any time it is not hooked to the truck.
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JRscooby
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I read the OP. All my posts have been critical of what he has been told about the hunt for the problem. And you are right, the probability of the problem coming from Break-away-switch is 0.
And the chance there is a issue with driving style might be pretty good, but that is not the only problem.
3 out of 4 brakes wore out. Fact is 25% of brakes not working will cause rapid wear to the ones that work.
And once he has looked at the shoes, he knows which wheel has the problem. And if somebody that knows what the are doing replaced them, about the only place the problem can be is electrical, and in the branch going to that wheel, or ground.
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edited 03/05/22 07:58am by an administrator/moderator *
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