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Trailer brakes locked up


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Driving from Hohenwald an hour away on an interstate doing 70 miles an hour I hit a lip on the road and my f150 showed a “electric malfunction “. I thought that my 7 pin might have come out but I looked back and the yellow lights on the side of the Ollie were on. So I continued on and suddenly a Good Samaritan flagged me and told me there was smoke coming out from the back of trailer. I pulled off and sure enough there was smoke coming from under rear tires. The tires looked good and could not see where the smoke was coming from. I took out my infrared temperature gauge and it showed that the tires were showing a readout of 150 degrees. I waited for about 15 minutes waiting for the temperature to come down. As I proceeded to start again I realized that the brakes were locked up. I then thought that the safety brake away had come loose. Nope it was in. So I had to get off the interstate and luckily there was an exit about 3 minutes drive away. So I limped off the interstate with smoke still coming out the back. At the end of the interstate there was a fire station and I was able to get there. With the help of the firemen we determined that the brakes had locked up. When we pushed the the safety brake plug we could hear the brakes release but as soon as I would try to start rolling they would lock up. So I called for a flatbed to take the Ollie back to the factory. I also called Jason and was lucky to be able to speak with him. He told me that if I disconnected the seven pin it would eliminate electric to the brakes and they would release. Did that but didn’t work. So he said that on the passenger side bed there was a pink wire that also provided electrical current. When we disconnected that wire and disconnected the seven pin the brakes finally released. So we had the flatbed pull the Ollie and I went behind to avoid anyone from hitting the back of the Ollie.


The diagnostic from Oliver was that the black brake release was full of junk and had failed. So we had it replaced and had the drums resurfaced. The brake pads were still good. We also had them repack the bearings since we had the tires were off.


There is also something that is important to know. If you take the black plug out it has to be put back in a specific way. If not you might find that it will at some point fail   A3A1BE54-4B43-45DA-AF3F-0B74978D6F70.thumb.jpeg.7a486d079c58446e8ebe92a5fcbe9278.jpeg



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why would you need to unplug the black brake release plug?


To test the system before a trip, it is highly recommended. You can use the opportunity to blow some compressed air inside the cavity to remove any junk or grit.... don’t forget to put the plunger back in ASAP so it doesn’t overheat the brake magnets. They are getting full 12 volt current, unlike from your controller which is normally way less.


I don’t normally move the trailer to see if the brakes lock up, you can hear the magnets make a loud clunk. That tells you that the switch is OK. If you have a digital clamp on ammeter, you can hang it around one wire and easily read the total current going back there, very nifty! It shows if you have a failed magnet (each draws about 3 amps).




John Davies


Spokane WA

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SOLD 07/23 "Mouse":  2017 Legacy Elite II Two Beds, Hull Number 218, See my HOW TO threads: 

Tow Vehicle: 2013 Land Cruiser 200, 32” LT tires, airbags, Safari snorkel, Maggiolina Grand Tour 360 Carbon RTT.

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