Testing Trailer Brake Magnets for Proper Function

Hello, I have been trying to test my 2003 GMC 1500 5500 lb towing vehicle with 5500 lb travel trailer elec brakes. I have noticed during wheel bearing inspection that one one the four trailer Brake drums did not have any marks from the elec magnet. Thus making me think that one magnet was not making contact with drum. This would be the front right side. I have a Tekonsha Prodigy P3 controller. When I jack up the front axle to test the brakes by putting a 1x4 from truck seat With key on trailer plugged into truck both trailer wheels turn, even with break- away key removed wheels will rotate. So I suspected a ground problem.and replaced two ground lugs and cleaned the connection to frame. Now the wheels of the trailer lock up while removing the break away key and while pulling manual over ride lever on controller. But when I place the 1x4 from truck seat to foot brake pedal the wheels on trailer do not lock up. May the foot pedal with not apply until I'm on the road, I don't know. Any ideas? Thanks, Paul

I am not electrician, but on a trailer with four 10" brakes, if min amperage at each magnet is 3.2 amps, how are you going to get the stated min combined 15 amps at the tongue? It seems to me that min combined at the tongue should be 12.8 (3.2*4) amps or each individual magnet min amps should be 3.75 (15/4).

Can you use a multimeter, that's equipped a DC AMP clamp?

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.