Fookin trailer brakes/HELP

[76zimmer]

I just replaced my controller, and have output to the 7 pin connector, a full 12 volts. I hear the magnets humming, but when I spin the tire by hand and have someone hit the brakes, nothing but a hum. I took one wheel hub/drum assy. off, cleaned everything, lubed the shoe rubpads on the backing plate, cleaned and lubed the adjustment wheel assy. adjusted the shoes out so they litely touch the drum, and WTF, still don't get anything but a hum.

HELP, I'm going wheeling on Wed.

 

[YZEATER]

everything moves freely in the drum?? the magnets move out towards the drum? 12 volts to the magnet?

 

[ktmoutfront]

The brakes should be adjusted to just where the wheel will not spin, then back the adjuster of one click.

 

[Fordum]

OK, couple of quick points. DC don't hum. The old style controllers would vary the current by use of a big ass variable resistor.
I understand some of the newer ones pulse the DC and vary the current by varying the duty cycle.
If that is what you have, you may be getting 12V with a really quick duty cycle. The magnet should stick quite strongly to the plate on the drum.
Since its an electromagnet there is not a lot to go wrong.
It either works, its shorted or its open.
If you are getting full voltage and current to the magnet and it is not grabbing the plate, the coil is bad.
Since you are strapped for time, we need to do some quick and dirty checks.

Run a wire from a known good ground to the trailer frame. Don't depend on the hitch or the ground wire in the 7 pin. In fact, unplug the 7 pin for these tests.

Then, when you are sure the trailer is grounded, run a wire from the battery to the wire going to the coil where it comes out of the brake plate. You may have to cut the wire going to the coil temporarily.
Quickly try to spin the wheel.
It will either spin or not.

If it does not, then quit working on the brakes at the wheel, they are fine.
If it spins, replace the coil or check the wiring coming out of it.

If it does not spin, take wire from the battery and shove it in pin hole on the 7 pin harness to the trailer. Does the wheel spin?
If so, then the wire from the connector to the brake coils is bad.
If not, then the problem is either the ground wire, the controller or the wiring inbetween.
Next, plug the 7 pin back in, cut the output wire coming out of the controller and hook the 12 volt to the end going to the trailer.
Does the wheel spin? If not, snatch the extra ground wire off and try again.

At this point, you should have a handle on where the problem is.
Some coils will overheat if you leave full voltage on them for a long period of time, so hook up the full 12, make your test spin, and then unhook it.
Better safe than sorry.
Let us know what you find.

J.

 

[76zimmer]

OK, with everyones help, ideas, links....I tested the brake circuit today on the trailer. I unhooked from the Burb, I took apart the plug on the trailer, and used a 12amp battery charger. I hooked the neg to the white wire terminal, and the pos to the blue wire terminal, with alligator clips. Turned on the charger, and spun the tires, and they stop immediately. OK, the trailer must be ok, I figure, so I check my recep. on the truck. Seems the ground has gotten rusty over the years so I repair that first. Continuity shows .03. Good on that now. I check the pin in the recep for power from the brake controller, and get nothing with the brake pedal pushed or the manual finger slide control engaged. So back up to the cab to check the controller output again. I just replaced this thing last Friday, and now I got no power out again. WTF caused this. I jump a wire from the batt. supply (12v) to the brake wire heading to the back of the truck. I get full 12v back there now. My brake switch supply is giving me a good bright test light when the brake is depressed, and my ground circuit to the controller is sound.
So I got another controller today, and will put that in first thing in the am. I'm pretty sure that has to be the problem. But I find it a bit surprising that the new one was bad.

Thanks a bunch guys.

 

[76zimmer]

another update, after talking with the Tekonsha tech dept. he had me test my unit in the following manor:

UNHOOK trailer connector from truck.
test the 2 pins on the trailer wiring plug (ground, and brake supply wires) with an ohm meter. They should read 1.0-1.5 ohms (my test meter was set on 200ohm) My trailer read 1.6, he said that should be ok.
On the truck, test for 12v ground circuit. Ensure it is sound.
test the blue wire out of the unit to the brake circuit by probing with a test light. When probed the green light on the controller should light up.
Then with the probe still in the circuit, slide the manual control and the test light should light up. This ensures the unit is functioning correctly in the manual mode.

My original problem was it wouldn't work in manual, or using the pedal.
I thought my ground was sound, as it was on the intake manifold, and the stud head was clean, and so was my wiring connector on the stud. What I didn't realize is the stud wasn't completely torqued down, and the stud had sealant on it. This may have contributed to a intermitently bad ground situation. I ran a direct ground to the battery, and have since had no problems.