I have an anderson open car trailer 22' with 3500* axles with brakes on both axels.

Last time i pulled it was to go to Bowling Green Ky and the brakes did fine and were on the normal setting that i use. The Gain was set at 45 with trailer loaded and 25 unloaded (anything higher than that it would lock up the tires). I took that trip last Nov.

I just pulled it back out from storage to go pick up so pipe and for the brakes to even grab i had to put the controller on the max setting and still it would just barley grab. I have cleaned all the connection and the controller putting out the different levels of out put to the plug and also to the controller box on the trailer.

i tried to adjust the brakes(adjuster wheel through the backing plate) to where they just grab when spinning them when jacked up but still have to put the controller on max for it to completly lock it up even with it jack up and spinning the tire by hand (and this is the same for all the brakes on all the wheels).

The shoes are worn about half way and i have cleaned the magnets.


I am just lost and cannot figure out why it still will not grab like it used too. Any suggestions would be greatly appreciated.

Thanks Jpope

Check the wire connections under the trailer at each wheel. I have a travel trailer that I was having brake issuse with. It ended up being a bad connection at three of the four wheels, where the magnet wires connect to the wires running down the frame from the truck connector. If I remember correctly the magnets should have a resistance reading of about 2 ohms each , so if all four magnets are connected you should have a reading of about 0.5 ohms from the connector to the frame.
Another one could be your controller. A bubby of mine had the opposite problem to you when he hooked his trailer up in the spring. With the controller set as low as it would go the trailer tires would lock up. He changed the controller and problem fixed.

If you do replace the controller I would recommend the Prodigy P3. It has a lot of diagnostics that are a big help when you have problems like you are having now.

well i dont think it is a the controller becasue it does the same thing with my dads truck hooked up and they are 2 totally different controllers and also the controler work perfect on other trailer we have tried.

I am going to check the wiring to all the wheels and see if that is the problem. They looked fine when i was adjusting everything but they may be corroted i might cut the connectors off and then solider the wires together and then put heat srink warap on it to protect it. Becasue all it has now is just the butt connectors.

While you are at it check the ground wire as well. Often the trailer frame is used for ground and those connections are notorious for going bad (especially on boat trailers). What you describe is classic of a bad ground.

Well guys i have worked on this trailer 2 different times now and tighened all the shoes up and also had a couple of wires that had rubbed and that were hitting the bare frame. I soildered them and heat srinked them everthing. Still have the same problem. I have cleaned the ground and still nothing has changed. I am going to run another ground to see if that may be the problem.


Does anyone else have any suggenstions. I looked at the magnets they look good and also the shoes are worn down some but still over over half left on the shoes. The magnets had some rust on the back of them could that be causing them to not grab like they used too. I am getting frustrated with this thing and just need some more options to get this thing fixed.

Thanks for the help guys.

Have you checked that your truck is feeding the trailer a good solid ground as well? Checking all the grounds on the trailer is good but useless if the ground coming from the truck is lousy.

Use a set of booster cables (to make a temporary ground setup) with one end clamped on a good ground on the truck and the other on a good ground on the trailer and try things again. If suddenly all is well your truck isn't supplying a solid ground to the trailer.

Never rely on the hitch/ball to supply ground - it MUST be passed through the connector to be reliable....however, if the ground through the connector goes bad then a trailer will often fall back to grounding through the hitch...which is usually not sufficient for high draw items like brakes.

Are ALL the lights on the trailer bright? Do they stay that way when the hazards are on? When the brakes are applied? When the trailer is rocked/jiggled while connected? Often lighting issues can be an indicator of grounding issues.

First, using an ohm meter, measure resistance between ground and the brake wire at the trailer plug (trailer side, truck not connected). On a tandem axle, it should be around 1 Ohm. Each magnet, by itself, measures about 4 Ohm.

When you say that you cleaned the magnets, did you ensure that swinging the magnet arm would expand the shoes? The pivot shaft can rust solid.


If your trailer is equipped with a functioning breakaway battery, with the breakaway activated, do the brakes lock up on an empty trailer?

If your trailer is equipped with a functioning breakaway battery, with the breakaway activated, do the brakes lock up on an empty trailer?

This is a good test to perform.
If you have good solid brakes with the breakaway I would then be suspicious of the 7 way connector on the trailer. You have indicated that all of the wiring on the axles has been checked out. Double check the ground wire on the 7way and make sure it is connected to the ground wire that goes to the trailer brakes. This is often a bunch of wires that make up the grounds on the trailer. Often the large connector that is used is not tight. You ruled out the truck when you said it did the same with your dad's truck.

You ruled out the truck when you said it did the same with your dad's truck.[/FONT][/COLOR]

Whoops, I missed that part. Yeah, problem is on the trailer side for sure.

Thats right it did the same with my dad's truck. Also i pulled another trailer and it worked like it sposed too had the controller set low around 15-20 and you could feel the trailer stopping itself unlike my trailer you have to put the controller on 40-50 for it to stop it self.

I will run new ground also check all the wires again like i said. But dealing with the break away it will not stop its self i tested it and it did not wouldnt even kick on the magnets (cannot hear them humming). Then i tested the battery for the break away switch and it was dead as a door nail. i tried to charge it but it wouldn't hold a charge (i am going to order a new one and also a charger) that uses the truck when it is hooked up becasue it does not have one on it that i can find. Dont know if that has anything to do with my problem or not. thanks for the suggestion on this problem and i will try all the suggestions that everyone has mentioned. Thanks