What is normal resistance reading for 5er brakes?

Don't know if all three axles have brakes, but if RoyB is correct about each magnet drawing 3 amps, then even 3.3 ohms would be high. But, you're right; the controller should do SOMETHING. It sounds like you have a factory controller since it is a proportional control and not an inertial type.

So, if the controller is "doing nuttin'", do you mean it's not recognizing the trailer? If not, then maybe it's just a bad connection at the trailer connector at the back of the truck (?) - common problem...

If you're sure the trailer connector in the truck is OK, check for water in the connector. I've heard where just a small amount of water intrusion will mess up some of the factory controllers. If you have a "Y" connector under the truck to provide for a bed mounted connector, don't forget to check there for water in that connector.

The brake controller always announces when I plug in the trailer. Then when I apply the brake or use the manual control, it displays a bar that shows more dots as the pressure increases. Right now, it's not doing nuttin'.

Ohms law V=IR or R=V/I says that if each axle draws 6 amps, the resistance would be 12/6 = 4 ohms. Three axles in parallel would read 1/R = 1/4 + 1/4 + 1/4 or 1/R = 3/4 or R=4/3 = 1.33 ohms and I'm getting 3.3 ohms. Even if one of the axles is disconnected (it's happened before), that wouldn't explain why the controller isn't doing anything.

I think the reading I got is in the ballpark. Open or shorted would indicate a wiring problem in the trailer. I think my problem is in the truck.

There's nothing mechanically wrong with the brakes. I adjusted them just before leaving on this trip.

You said you had a Tri-axle rig.. so that would be six magnets. If you are measuring the actual ohms of the magnets when all together, which it should be just as you describe it, you should see less than one ohm I would think.

Perhaps you are only applying voltage to one axle instead of all three? With some long jumper wires and a lot of fiddling, you should be able to determine if you have continuity in both the positive feed, and the return feed from each wheel back to the connection plug. Finding the common feed and possibly the disconnection point will be difficult.

Everywhere I have read is the each brake magnet will pull 3AMPS when 12VDC is applied... One axle this will be 6AMPS - Two axles it will be 12AMPS DC Current.

Also on my fifth wheel I can hear a low tone if I have my ears up close to the brakes when they are activated. On my POPUP trailer I do not hear any audible tones.

The compass idea also works great too... Just hold the compass up close to brake magnet on the outside of the wheel and it deflects big time when the brake magnet has DC VOLTAGE applied to it.

DO not expect to hear the brakes working with the wheel jacked up and sitting still. On my two trailers I have to turn the wheel about a quarter turn to have the electric brakes engage when the electric brakes Dc VOLTAGE has been applied. There is some sort of mechanical action required to make them work with the moving brake drum.

On inspection one time I thought my brakes were not working as well and when I moved the wheel about a quarter turn the brakes engaged on the wheel I had jacked up.

Roy ken

Sounds pretty close, but I'm not sure what the exact reading would be. Does your brake controller show a good connection or give you any error message?

One way to tell if the brake is working at each wheel is to hold a compass right next to the hub of each wheel while someone applies the brakes. The compass will deflect.

If your brake controller looks OK, they may just need adjusting. Most trailers, as they come from the factory, are not self adjusting. They adjust like a regular star wheel adjustment.