My brake controller again

I spent time today between other projects, on my Tekonsha Voyger 9030 brake controller, for my tractor hauling trailer. I have 12 plus volts to my magnet from the controller, but it doesn't activate it, only a slight humming noise. I have a wire directly from my battery, so I am sure it's grounded. Is it possible to have 12 volts, but not enough amps from my controller to activate the magnet? 12 volts from a battery charger locks up the wheel just fine. Stan

Are you testing the 12v with the magnet connected?

Try testing with the magnet connected, see what voltage you get. It probably won't be full 12v unless you are applying the controller with the manual over ride.

If the voltage is low, start testing back to the controller itself.

If good at the controller, but low at the magnet, there is a wiring problem.

those magnets are many times grounded to the frame and that grounded to the wiring plug again at the hitch area.
the grounds fail and the system becomes problamatic.

that and the system requires periodic brake adjustments. if let go eventually they will not expand enough to even contact the drum.

ADJUST THE SHOES applying and working them with readjustments to properly center the shoes

AND REWORK ALL GROUNDS at magnet at trailer frame at harness at truck frame

Yes it is possible to get a 12 volt reading on a test meter and still have a wire broken (only one little strand still touching) or corroded at a connection. The wire will allow enough current to get a reading but when you need real current flow for it can't handle it. When this is the case the voltage reading usually drops bad if testing while the load is applied to the circuit.

TJV is dead on. Test the voltage with a load on it, i.e. the brakes applied and see what it is. I just had the same thing with the tail lights on my bumper pull. Test light and meter showed power. Turn on the lights and it dropped to nothing. Bad connection under the truck.

I had a problem with my trailer brakes, 12 volts at wheel, no brakes, wires too small, bad connections. Ran new wires #8 from where pigtail connected to the trailer, to the left axles, then new wires #10 across the axles to the right side, good brakes after that. You need to have at least # 12 wires to get enough current to make the brakes work. The bigger the better. Most trailers are wired with #14 wire, which is in my book marginal. If your trailer is wired with anything smaller than that, you will not have any brakes. The other problem I found is that the connection between the pigtail and the trailer wiring was faulty . Good luck.

Stan,
Measure the voltage and the current.
12v and no current means you have an open.

Look at the electromagnetic. You may see the coils have rubbed on the plate.

Don't replace just one magnet, replace all 4.

I replaced one and it was stronger than the other 3. Things get a little crazy when you applied brakes. George

I wonder how many scotch locks are in the circuit.

google scotch locks 3m

They should be on everyone's kill list cut them out and hard wire...

Something about the fact that you have been reporting humming bothers me. batteries and DC supply systems (real DC, not rippling DC like voltage) should produce no hum. If your controller (I do not know what it uses for output) produces pulse width modulated DC) it would hum.
I would do these tests: measure pulse DC voltage across the magnet at the magnet ground, and magnet input, (might take a Fluke Meter) with ----- marks on the DC meter position) when applied fully. should read 12+ volts and be locking the wheel.
I would next measure the amps on the wires going to the magnet when using the charger to make it work. Even a good amp meter from a tractor would work. it should show ~ 5 or more amps.
I would measure the voltage at the plug connector wires (while connected) to see if it is actually getting power when applied through the truck system.
A 4th test is to use a jump pack or good 12v battery at the connector in place of the charger. If it works there, it is the truck, not the trailer.
My bet is on a bad truck ground, or connection in the truck.
I just experienced a faulty connection in a Jeep from the key start position to the starter (tiny box) relay. it measured 12+ volts when disconnected, but would not latch the relay (probably only took 100 milliamps to make it engage). When loaded with the relay the voltage was 0.2v. I bypassed the wire in the loom and all is well. Jim

Yes a multimeter will show 12 volts, and not have enough amps. Run into this all the time at work. If you have an old 12 volt horn, hook it directly to the battery and hear what it sounds like, now hook it to your brake wires and see if it makes the same sound. Then maybe hook it to the trailer connector on the back of your truck to see what it sounds like. A little annoying if you have neighbors. I have a buzzer at work that is from a trucks low air system that takes some amps to work. Maybe use a blower motor or anything that needs some amps to work.

Are you sure your magnets are not bad? At the weld shop we no longer replace just the brake shoes when new are needed. We replace the whole backing plate that comes with new shoes and magnuts. For just a few dollars more you can replace with everything new. Magnuts seem to go bad about as fast as the shoes.
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I have tested many brakes with direct wire from a battery and it will lock them up. The brake controller restricts the voltage to the magnuts so they don't lock up with a full 12 volts I do believe.

Using a battery charger will produce 120 Hz humming.
Sounds like the hummer bearing in the magnet is bad.
12v DC, no humming.
geo.