Testing Trailer Brake Magnets for Proper Function

The information contained in the section "Testing with Trailer Connected to the Vehicle" is the same as I see on other websites as well, but when I try to test amperage this way on my Tekonsha Prodigy P2 Trailer Brake Controller it tells me no connection and won't output. It sees the connection fine before adding the multimeter inline to test. How can I test the overall trailer brake amperage if this doesn't work and why would it not see the connection with the multimeter inline? Thanks

I have not gotten any answers out of Ford: . . . . .So went to a large dealer and talked to the service manager about the warning message that fills the entire dash “WIRING FAULT ON TRAILER”. When this message appears no other information appears on the dash, which requires you to hit the OK button while braking to clear a message as you are driving with no apparent cause or meaning. The dealer has no way to troubleshoot why this warning is coming on. He has no technical detail on how much brake current is too much at any given speed or how much input to the microprocessor is receiving from the other computers on the truck. Since there is no interest from Ford in fixing the Hazard warning label while using the brakes to slow or stop the F-350 truck. The manual under Information Display Warning Messages has this statement: “the trailer brakes may be drawing too much current” what does that mean ? The dealer does know what that number is. I never have that warning light appear when pulling a double axle trailer with 4 brakes. I appears often a lot when pulling a triple axle trailer with 6 brakes. I think the Ford trailer brake system cannot handle the current draws when all 6 brakes are engaged. But with no spec supplied to the dealer and no way to test what that trip point is. The microprocessor controls all of these items yet the dealership cannot check or verify any of these operations. • The trailer brake controller is equipped with a feature that reduces output at vehicle speeds below 11 mph (18 km/h) so trailer and vehicle braking is not jerky or harsh. This feature is only active when applying the brakes using your vehicle's brake pedal, not the controller. • The controller interacts with the brake control system and powertrain control system of your vehicle to provide the best performance on different road conditions. • Your vehicle's brake system and the trailer brake system work independently of each other. Changing the gain setting on the controller does not affect the operation of your vehicle's brakes. What I need Ford to do is help the dealer run checks or simulations to stop the need for the Hazard Notification with no solution to be displayed on the dash that block all normal displays that are shown on the dash. Trailer Fault Indicator on Dash Can you change the parameters on the Ford brake controller ? Can the dealer change the upper current limit on the brake controller when engaging 6 brakes on a triple axle trailer ? I looked in the Manual as to why does the trailer fault display on the dash The dealer tech does not have all the parameters on the brake control That’s what I’m requesting are the parameters that the brake controller sees before the display is shown on the dash I think the random display is caused by the trailer brakes exceeding the current draw limit built into the brake controller. This display warning only occurs with this triple axel trailer toy hauler, no other trailer causes the warming. But the other trailers do not have 6 electric brakes connected to the F-350. When the brakes are applied too hard all 6 brakes draw too much current versus a dual axle trailer with only 4 brakes needing current. The dealer has done the simple test that dealers can do, they find no problems with the very basic test. A trailer repair place said there is no problem with the trailer brakes. And the warning hazard does not occur on an ongoing regular basis only when the brakes are applied too hard. I push the OK button everything is fine until I apply the truck brakes too hard, which causes all 6 brakes on the trailer to engage, this again exceeds the upper limit that the brake controller thinks is excessive and displays the warning on the dash. Most trailers only have two axles or 4 brakes, not 6. This exceeds the controller trip point for a higher than normal current draw. The solution is to program the control to a higher trip point due to 6 trailer brakes drawing higher Amps during a normal braking operation. In the Ford manual on page 296/666 it states this: TRAILER BRAKE MODULE FAULT Displays in response to faults sensed by the trailer brake controller, accompanied by a single tone. If this message appears, contact an authorized dealer as soon as possible for diagnosis and repair. The controller may still function, but with degraded performance. WIRING FAULT ON TRAILER Displays when there is a short circuit on the electric brake output wire. On page 297/666 it states this: If this message displays, with no trailer connected, the problem is with your vehicle wiring or trailer brake controller. Contact an authorized dealer. If the message only displays with a trailer connected, the problem is with the trailer wiring. Consult your trailer dealer for assistance. This can be a short to ground (such as a chaffed wire), short to voltage (such as a pulled pin on trailer emergency breakaway battery) or the trailer brakes may be drawing too much current. Points to Remember Note: Do not attempt removal of the trailer brake controller without consulting the Workshop Manual. Damage to the unit may result. • Adjust the gain setting before using the trailer brake controller. • Adjust gain setting, using the procedure above, whenever road, weather, trailer, or vehicle loading conditions change from when the gain was initially set. • Only use the manual control lever for proper adjustment of the gain during trailer setup. Misuse, such as application during trailer sway, could cause instability of the trailer or tow vehicle. • Avoid towing in adverse weather conditions. The trailer brake controller does not provide anti-lock control of the trailer wheels. Trailer wheels can lock up on slippery surfaces, resulting in reduced stability of trailer and tow vehicle. • The trailer brake controller is equipped with a feature that reduces output at vehicle speeds below 11 mph (18 km/h) so trailer and vehicle braking is not jerky or harsh. This feature is only active when applying the brakes using your vehicle's brake pedal, not the controller. • The controller interacts with the brake control system and powertrain control system of your vehicle to provide the best performance on different road conditions. Thus controller has a microprocessor that handles all of these inputs from different systems on the F-350 truck.

Replaced all 4 trailer brakes with new shoes and magnets etc. after adjusting then very weak brakes. Adjusted them 3-4 times still the same. Tested the truck and it’s giving out 12 volts at trailer plug. Tested wires by brakes and when manual override lever for brakes is applied Im only getting 10 volts at each individual brakes. Tested the resistance of each magnet and it’s 2.7ohms. Range is 3.0 to 3.8 with 12 inch brakes does that mean my magnets are junk? Also I’m not hearing a constant humming noise at the brakes when voltage is applied. Does this mean the magnets aren’t energizing? I think I need new magnets just want to get opinion from experts. Thank you

I have a 2016 f 350 diesel and a Legend 24 ft aluminum trailer I just did a full brake job to trailer cause brakes where done and system was giving me a trailer disconnected message. Well everything new and still giving me that message. I have all lights working perfect but no brakes. Any thoughts Thanks Jim

If I disconnect the rear axle brakes will the front axle still work?

when I pull emergency brake voltage drops to 10 volts from 12v and brakes very weak I've adjusted brakes and wires look good (trailer is 6 months old)

Just put new brakes on trailer that had minimal braking. install complete brakes with magnets ect. with trailer raised in the air when you apply the brake via the controller all brakes lock up. When trailer is on the ground hooked to truck then you activate controller fully the brakes slow the trailer but not very good. Adjusted brake shoes several times. Any help ?

My 2018 tundra flashes from trailer disconnected to connected This is a brand new axel I put on and wired, this has never happened while towing other trailers with brakes

I have tested the resistance on all four of the brake magnets on my trailer. 3.0, 3.2, 3,2, and 3,2. However, when I check the amperage I am only getting 12.8 amps for the 12 in brake drum brakes. Do the brake magnets need to be replaced even though they are within spec? Using a prodigy P3 brake controller to check the amperage.

I used a battery charger as a voltage source. I got a lower current than expected, even though the DC resistance check out. Ohm's law seems to be violated in my garage. But then I realized the "DC" output of a batter charger is not true "DC" but is usually full wave rectifier waveform. Therefore the magnet exerted inductive reactance on my battery charger voltage source, reducing the current. I'm just saying, be advised that a batter charger does not produce a true DC voltage.

I have two trailers and a brand new silverado 3500 hd work truck, On my dump trailer, I get " brakes connected" several moments later check trailer wiring. This goes back and forth on its own even with the truck just sitting there. Its been in the dealership twice but all the found was a blown trailer break fuse in the fuse box and a rubbed out nuetral between front of truck and connector. Need help on how to test the trailer for some mysterious issue. All trailer brakes appear to work.

In your picture for Individual Brake Magnet Amperage Specifications, you have the negative of the multi meter connected to the magnet and negative battery terminal. But in your dictation you say to connect the positive of the multi-meter to the magnet and positive battery terminal. Which is it? I connected the positive of the multi meter in line with the battery and brake magnet, then connected the negative of the brake magnet to negative on the battery. I got no reading on a brand new brake magnet, what is the problem?

Some great testing ideas and specs from a company that I have purchased many repair parts for my fifth wheel.

Got brake problems,magnets are humming,shoes are adjusted with some drag,still no brakes,these are new brake assemblies,whats going on?

I just recently picked up a 16 foot flatbed trailer with brakes. Someone has removed the brake harness from the axle forward. Both wires coming out of the brakes are green. There’s one of these go to ground and the other one to the power source on my seven wire plug? With both of them being green does it matter which one goes where?

i have 12volts going to front axle black and white wire but no brakes

What if the code S.H. stays on when the trailer is disconnected? Does this indicate that the problem is with the truck wiring?

The directions for determining the amperage across the blue wire does not apply to any brake controller that requires resistance (a load) to function. Example: Curt Triflex requires an electrical load be sensed before the controller will send a signal in the blue wire (signal = power) . A simple 12V test light shining brightly is a suitable indicator of signal.

Best troubleshooting guide on the web. Thx