Brake magnets not energizing. What do I need to check

[wowzer]

Doing some preventive wheel maintenance and was checking magnet performance and to my surprise when the brake pedal was pressed the magnet did not energize. Is there a fuse or checks I need to do to help track down this problem?

[N6ZCM]

Check your vehicle fuse panel for "Electric Brakes", I would also venture to say there is a fuse panel/circuit breakers on the trailer for brake lights, park lights, power from tow vehicle, back up light, and brakes. probably near where the umbilical cord from TV to trailer come into the trailer.

You are connected to the tow vehicle?
So I take you spun the wheel and then had someone step on the brake or used the brake controller?

[wowzer]

Camper plugged into truck. Had wife step on brake pedal. Drum was removed so magnet was exposed. Held some tools next to magnet and would not hold.

[M109Rrider]

Probably not the best way to test them. Is there a reason you believe they weren't working? I would put everything together and and pull the emergency pin and see if it locks. I found a wheel that wasn't working that way.

[Bama Rambler]

Was it just one or was it all of the magnets not working?

If it was just one, it's likely a bad connection near that brake.

[Bluepill]

You can verify the wiring on the trailer as well as the actuation of the brakes by jumping directly from the trailer battery to the brake wire at the trailer-to-tow vehicle electrical connector.

If it works this way, your problem is in the tow vehicle.

Check youtube for videos.

[larrytbm]

Yea, I would try the break away pin technique first if the camper battery is charged. If they work , then problem is in the tow vehicle. Don't leave the pin removed for more than a few min, or the switch may melt.

Also if the brake controller gain is set too low, there won't be enough energy going to the magnet to really activate it with much force.

And as stated, you need to determine if it is just a single brake or all of them.

[wowzer]

Never messed with the breakaway switch. Just push the pin back in to reset?

[prairiecamper]

Originally Posted by wowzer

Camper plugged into truck. Had wife step on brake pedal. Drum was removed so magnet was exposed. Held some tools next to magnet and would not hold.

Stepping on the brake pedal is not good way to check trailer brakes. If you have an inertia type brake controller they have a built in accelerometer therefore you need forward motion and deceleration happening for it to send voltage to the trailer brakes! A better way is to have someone activate the brake using the manual slide lever on the brake controller. Obviously the tow vehicle 7 pin plug needs to be attached and subject wheel off the ground ready to be spun.

[larrytbm]

Originally Posted by wowzer

Never messed with the breakaway switch. Just push the pin back in to reset?

Yes, they are cheap and with 12 amps going thru the contacts they will melt. Especially if the contacts are dirty.

[Bikersarge]

Originally Posted by M109Rrider

Probably not the best way to test them. Is there a reason you believe they weren't working? I would put everything together and and pull the emergency pin and see if it locks. I found a wheel that wasn't working that way.

X2, this will let you know.

[Flybob]

If you have the drum off, you should be able to see the shoe mechanism move when the brakes are applied. If nothing, check the wiring. FR and other use wire nuts to make the connections under the unit. Nothing better than an open wire nut in a dirty wet environment. It is a good idea to pull the breakaway pin every so often for a minute or so to keep the contacts clean and to keep it from freezing up in place.

[prairiecamper]

Originally Posted by Flybob

If you have the drum off, you should be able to see the shoe mechanism move when the brakes are applied. If nothing, check the wiring. FR and other use wire nuts to make the connections under the unit. Nothing better than an open wire nut in a dirty wet environment. It is a good idea to pull the breakaway pin every so often for a minute or so to keep the contacts clean and to keep it from freezing up in place.

Actually just by applying brakes you will see no movement of the brake mechanism, it actually takes rotational movement of the drum to activate a braking action. This is because the magnet attaches itself to the vertical surface of the drum on brake application and the lever attached to the magnet through the brake mechanism moves the shoes apart as the drum rotates and the magnet moves in the direction of drum rotation.

[babock]

You will not see anything happening with the drum removed since the magnet is magnetized towards the drum.

[TitanMike]

Before jerking out the emergency switch pin try activating the manual lever and make sure nobody has rotated the adjustment wheel to the point there's not enough power to energize the magnets.

It's also a good idea to check the plug on the trailer pigtail if it has a few years on it. I just replaced one on a commercial trailer at my son't business. They hang out in the weather when not used and the contacts can corrode bad enough to prevent even low current LED lights from working. Super bad on high current items like 4 brake magnets.

A thin screwdriver and a strip of 600 grit wet/dry sandpaper can make an old plug/receptacle work like new after the surface corrosion is removed from the contacts.

[CedarCreekWoody]

Did you manually apply the brakes with the hand switch on the controller? Many of the controllers activate by momentum of a moving vehicle slowing. If your truck wasn't moving the controller does not activate. Press (or squeeze) the manual application switch.

[wowzer]

Can I also do a voltage check on the tv plug to see if power is there? I use to hookup and put tv in drive at idle then manually apply the brakes. Would stop just fine. Did this last trip and it just kept rolling. Brake controller maybe? Looks like I have a lot of things to try tomorrow.