2010 MFI Trailer will not release brakes in reverse

[rkluck]

I have a 2010 MFI trailer works great except in reverse it just started to not release the brakes.
I have tested and know that when in reverse the electrical connection from the truck to the trailer is activated. This weekend I will be at the trailer and will check to insure there is not a broken wire in or bad connection in the trailer.

My guess is that the wiring will be OK. Does anyone know if the reverse lockout is just a solenoid that I can check (using an ohm meter (basically a coil I think)) and if these are available without having to purchase the whole front actuator?

 

[itsdgm]

Possibly try giving www.pacifictrailers.com a call. Maybe they can help diagnose it over the phone.

I would think that you should hear a "click" when 12 volts is applied to that solenoid. Maybe try having somebody engage the vehicle in reverse and listen for it. Or just jump 12v directly to the solenoid to see if it's activating. Other than that I would think that it would require a good ground to the vehicle and that the solenoid is grounded as well. So check for loose or corroded wires and possibly corrosion around the solenoid that could cause it to lose ground.

Good luck, keep us posted.

 

[rkluck]

Yes that is what I was thinking as well. I believe it is simple solenoid. If I don't find a wiring issue I will call them and see what options I have on parts. I will let you know what I find.

 

[Ronnie]

Take a look at pacific trailers website . They sell all the trailer parts and assemblies I can think of. In sure you can get the solenoid alone or as part of the surge brake actuator assembly. I think the latter is under $150.

I took mine apart a few years ago to replace a broken safety cable. Be forewarned, if you have to replace either it could take more than a few hours, most of it disconnecting and reconnecting the line to the solenoid.

There is not a lot of room for a wrench in there so if you want to say time and your knuckles I recommend that you do yourself a favor and disconnect the entire folding tongue assembly to screw and unscrew the brake line from the solenoid.

 

[Boat Crazy]

Have you tried backing with locking device in on trailer? Have you checked brake fluid?

 

[Captbob]

I just finished that whole process. If you replace the solenoid, you will need to bleed the brakes to remove the air from the lines back to the calibers. After many failed tries to get all the air out, I found that the factory installed calibers were upside down causing air to be trapped in the line. Mine was a 2010 MFI trailer. The calibers had to be switched from one side to the other to correctly get the air out. Check to see that your bleeding valve is on the top.

 

[rkluck]

Well mine is a 2010 MFI as well so I will check that. The trailer did not have a lock out device but I bought one in order to back up. I have not checked the brake fluid (trailer is used once maybe twice a year) but the trailer worked fine going forward. How would the brake fluid cause the brakes to stay locked in reverse? I am missing something (not unusual). I will look this weekend for the reservoir and check the fluid.

 

[Ronnie]

Do you press the little tab under the tongue?

 

[Captbob]

Are you sure there is not a solenoid inside the actuator housing? I was under the assumption that all the MFI trailers came with at least one set of disc brakes. Any trailer with disc brakes must have a reverse solenoid to direct the brake fluid back around to the master cylinder while backing up or the brakes will go on. If the solenoid fails for some reason, such as the electrical line being disconnected, there is a small lock out device that can be placed on the side of the actuator that will keep the brakes from working.

 

[rkluck]

@Ronnie Is there a tab under the trailer tongue that I should press? Maybe I did something that triggered this all of a sudden.

@Captbob I am sure there is solenoid and I need to determine if that is at fault. I recently purchased the lockout but that is only for reverse and if I levae it in the brakes will not work. Unless I have done some wrong (like Ronnie pointed out) and this is a simple fix I know the problem is in the trailer either wiring or the solenoid.

Thanks for the responses.

 

[Captbob]

It is fairly easily to determine if the solenoid is bad. If you have a jumper battery box, then you can use it to listen for a click when you sent a charge to the solenoid. Ground the jumper box to the trailer (black cable). The blue wire on you trailer plug is usually the positive wire to the solenoid. You can use a small nail in the end of the red jumper cable to make contact to with the blue wire. Tap it off and on and listen for a click each time. If you get the click, then you have a problem somewhere else.

 

[Ronnie]

There is a small tab on the bottom of the tongue a few inches / less than a foot from the receiver cup / ball mount but I believe it is used to release the brake before trailering. My trailer has a decal near it that states it should be pushed before trailering. Sorry to confuse the situation, unrealized now that your brakes won't engage not disengage.

I Hope it's just a loose wire / bad connection, as a stated earlier, it's a pita to remove / reinstall.