My trailer didn`t pass its annual inspection as they said the emergency brake doesn`t work. 

How does one test the emergency brake?  The issue is not the brake battery - that tests as fully charged when I press the "test" button on the battery.

What other place might be a likely source for it not working and how would I go about doing the repairs?  The trailer is a 3H slant BP.

Thanks!   

I bought this trailer (used) 1 year ago, and I remember my husband saying that he thought the cable for the emergency brake was too long.  Perhaps that`s why the inspection person thought it doesn`t work? 

How do I determine the correct length for the emergency brake cable?

The E brakes are tested by pulling the lanyard that goes to the switch on the E battery box. This sends battery voltage through the brake circuit activating the brakes.

If the brakes aren't working and the battery tests for a full voltage, then there are a couple of things to check. The first is the switch. It may have dirty contacts from corrosion. This is because the switch is so infrequently used. Moving the switch with some added dielectric grease, will usually clean things so they work. The second is the wiring contacts of the hot wire, from the battery to the trailer's wiring harness. The third and last is the ground wire contacts from the battery to the trailer's ground.

This is assuming that the trailer brakes are functional when activated by the truck's controller.

As far as length of the pig tail, it should be longer than the chains and shorter than the trailer's plug. If the hitch fails, you want the chains to hold and still to be able to maintain some braking control from the truck. This will allow you to steer and determine the direction of the trailer. If the chains fail and the plug is ripped from the truck, the E brakes are your last hope to stop the run away.

Some people don't use the E brakes, saying that they don't want to be near the trailer that has broken free. There have been several instances of innocent people being killed, by unguided trailers that have broken their hitches and safety chains, and had no functional E brake systems. Fortunately, most of those guilty, inconsiderate drivers are behind bars.

The trailer brakes to my truck are definately functional.  When I drove out of the inspection station they had set them to "max" which I then had to readjust.

We cleaned the inside of the switch with electrical contact cleaner.  Would this be enough to get the switch functional again, or do I also need to use grease?

We don`t have dielectric grease - is there another grease we can subsitute if the electrical contact cleaner isn`t enough?  We have WD-40, Jig-A-Loo, white lithium grease and some other lubricating oils. 

When applying non-spray grease do I apply it to the plastic piece that pulls out of the switch (does this get enough grease into the switch?) 

Why don't you ask the shop that tested it what failed?

They can tell you how they tested it and what failed. They probably pulled the lanyard out and when the wheels still turned gave you a failing grade.

If you can get the trailer brakes to work with your in cab controller, then brakes are probably fine and the problem will be with the switch, the wiring from the emergency battery or the battery.