trouble shooting non functioing trailer brakes

I just got a 98 Circle D deck over trailer. The brakes do not appear to be working. I tried to manual apply them with the brake controller and I thought I could feel something but I know the trailer was not slowing me down.

1. The break away battery has less than 2 volts in it now, so it needs charging, or is it shot?
2. If the battery is good, does it charge while it is plugged into the truck? My other trailer has a built in charger, but this one does not.
3. This trailer may have been sitting for long periods of time. Is the most likely problem, rusty drums and they will need to be manually cleaned? I would like to be able to get them to work with out doing more than I need to.
Thank you
Steve

check the voltage while attached and running

it'll tell you if it tries to charge

most likely problem is grounds

a good solid ground through plug

and good solid grounds to the frame at every location

every one of them everywhere

pretty simple check the grounds

sounds simple

I plugged the trailer in and started the truck. I still have just 1.8 volts at the battery. I quit because it started to rain again. I will remove and re-install the ground wire tomorrow.
i think the last owner of this trailer used it only to haul stuff around their property. I doubt that the brakes have been used in years.
Thank you
SDE

Jack the tires off the ground and spin the tires,hit the brakes(two people) you will know really quick if and which brakes are working. Most of the trailers I have worked on have those D--mm Scotch Lock wire connectors on them at the axle, sometimes just squeezing them with a pail of pliers is all it takes to get them working again. Also if it comes to it, you can wire a battery straight to each wheel,(12V) one at a time to check the brakes.

the battery is only used when the breakaway cable is pulled out... While you probably have a bad battery and need to fix it,, and the charging circuit, The battery should charge off of a separate 12 volt lead coming from the truck designed only to charge the emergency brakeaway battery.



you need to find out why the brakes are not working off of the brake lead coming from the truck... That lead comes from the trailer brake controller in the the truck that is designed to feed the axles on the trailer.

Both reguire a good ground.

The break away battery should charge from the truck. Good or bad, when connected to the truck there should be truck battery voltage present. (Engine may need to be running depending how the truck is wired.) If the battery is over a couple years old you can assume it's bad.

If you're going to be using the trailer on the highway, and you suspect it hasn't been off the farm for a while, now would be a good time to pull the drums, inspect and pack the wheel bearings, and check out the brakes and wiring while you're in there.

Trailer manufactures are notorious for shortcutting wiring, leaving wire hanging down, routing it through pinch points, and using those TOTALLY WORTHLESS blue fold over connectors! If it has the fold over connectors, might as well replace them now (solder and heat shrink) or forever have wiring troubles.

First check your plugs for corrosion. That is the most common place for problems by far. Helped a lady at a rest area in Il. a while back had the same problem. A bit of WD 40 and she was good to go. After that check your wires to make sure they are good. Just apply power and use a test light to see if you have power at all the wheels. Make sure you attach the ground for the test light to the ground for the brakes so you test the ground and hot wires for each wheel. If all that is good, the next step is to jack up the trailer so you can spin the wheels. Then Apply power to the brakes to see which wheels work and which don't. You can use your truck if you like or a battery charger works good too, but they have to be the old style with the needle gauge, the new ones with the digital readout won't work. You can also use a 12v battery with leads, but don't let it be hooked up too long because it can heat up the wires if they used small wires as most commercial trailers do. Just spin a wheel and have your helper apply the brakes, if they don't hit and stop hard you have a problem in that wheel. If you do it in this order you will eliminate each problem as you go so you're not chasing phantoms because something up the line is only working part way or not at all. As for the break away battery some charge from the truck and some don't. There is no way to know which you have without seeing your system. Most of the older trailers did not charge that battery, most were disposable dry cells. You will be able to tell by looking for the charging wire from the harness to the battery.

Before you tear into it.
Connect the plug - pull it out and tap it against the bumper to shake out any crud that has built up on the contacts.
After the plug is disconnected blow the crud you dislodged out of the socket, even with your mouth will do.
Repeat this 4 or 5 times every time you hook up a trailer and 90% of your problems will magically fix themself.

After just having gone through a deckover with bad brakes, it can be multiple problems once they have been let go awhile.

This one had bad plug, very bad splices, bad breakaway battery, bad grounds at magnets and one bad magnet.

There is no hope for the breakaway battery at 2 Volts. Replace it before you get the trailer inspected.

It does not have anything to do with normal braking, though. You can troubleshoot and fix the problems without it.

Normally the problems with electric brakes are wiring and ground. If you start from scratch with good 10ga wire and rewire the brake system, that should fix your problem.

You may also need to replace the magnets in the brakes themselves but you won't know until you get the wiring and grounding sorted out.

gotta go with Steve here - bite the bullet - go through everything.

Pick a nice day, do it once, do it right. A trailer you can depend on 100% is worth its weight in gold.

You'll be able to fully rely on it for a whole year (that's about how long it takes for your wiring harness to catch on something and get ripped out, or some other such disaster which will require doing it all over again). Longer if you're lucky.

Thank you everyone for your suggestions. The plug has a little coating of green corrosion on it. I will start by cleaning it first. As far as the break away battery, I did not expect that to be the problem with the brakes, but I did not want to be overlooking the simple stuff(KISS-keep it simple- stupid). I will jack it up and put the jack stands under it and see what I can get to happen when I apply 12 volts(battery) to each brake. Then I will probably remove each brake drum and clean and inspect them. Or buy new backing plates, like I did with my other trailer.
Thanks again
Steve

If your plug is green cleaning it will at best get you a day or two of use, I strongly suggest that you just replace it. That should be done yearly every spring anyway. This is a common time for this to happen, they get in the salt in the winter and get corroded. Then you spend most of the summer trying to save it only to get frustrated and replace it in the fall. Then it gets salted again in the winter and starts the process all over again. If you replace them every spring as regular maintenance, you get a whole year of trouble free use out of them.