Trailer Wiring Fault/Loss of Brakes - Page 2

Trailer Wiring Fault/Loss of Brakes

This is a discussion on Trailer Wiring Fault/Loss of Brakes within the F150 Ecoboost Towing forums, part of the F150 Ecoboost Forum category; Sorry Max, didn't mean to be snarky. I really just don't know anybody who owns a truck or trailer to borrow. I need to move ...

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Thread: Trailer Wiring Fault/Loss of Brakes

  1. #11
    Rookie pmah2017's Avatar

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    Sorry Max, didn't mean to be snarky. I really just don't know anybody who owns a truck or trailer to borrow. I need to move to a more truck/camper friendly place.
    I'm pretty sure its in the trailer now. I don't think there is a problem with the brake pedal sensor because the light will glow bright and all bars light with the pedal as long as the truck is in motion. I have also intermittently had the fault and lose braking upon starting the truck with the brake on but not moving. I now suspect I have an intermittent small short in the trailer brake wiring, or a bad magnet, which causes an over current and shuts down the brake controller. Interesting that the GMC behaves the same way. The moral of the story might be that having the brake controller shut down momentarily when it detects an over current is bad, and sounds like a real safety problem, but having the brake controller fry itself when your brake wiring is totally shorted out is really bad, so you should take even intermittent trailer wiring faults seriously. Is the threshold for shutdown on Ford lower than others? Maybe, but sounds like GMC works about the same way. All controllers have a limit of how much current they will send to the trailer so our controllers are just doing their thing.
    I fixed the grounds and adjusted brakes on one side yesterday. I used a 2 amp battery charger to activate the brakes and everything worked. I didn't connect it to the truck. If it ever stops raining I'll do the other side.

  2. #12
    Eco-Beast madmaxmutt's Avatar

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    Quote Originally Posted by pmah2017 View Post
    Sorry Max, didn't mean to be snarky. I really just don't know anybody who owns a truck or trailer to borrow. I need to move to a more truck/camper friendly place.
    I'm pretty sure its in the trailer now. I don't think there is a problem with the brake pedal sensor because the light will glow bright and all bars light with the pedal as long as the truck is in motion. I have also intermittently had the fault and lose braking upon starting the truck with the brake on but not moving. I now suspect I have an intermittent small short in the trailer brake wiring, or a bad magnet, which causes an over current and shuts down the brake controller. Interesting that the GMC behaves the same way. The moral of the story might be that having the brake controller shut down momentarily when it detects an over current is bad, and sounds like a real safety problem, but having the brake controller fry itself when your brake wiring is totally shorted out is really bad, so you should take even intermittent trailer wiring faults seriously. Is the threshold for shutdown on Ford lower than others? Maybe, but sounds like GMC works about the same way. All controllers have a limit of how much current they will send to the trailer so our controllers are just doing their thing.
    I fixed the grounds and adjusted brakes on one side yesterday. I used a 2 amp battery charger to activate the brakes and everything worked. I didn't connect it to the truck. If it ever stops raining I'll do the other side.
    No worries. Like I said, it seems like you are on the right track to solving your problem.

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  3. #13
    Rookie pmah2017's Avatar

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    Finally got a chance to finish my trailer brake project. I did fix a spot where the brake wire could bounce/rub on the trailer shackle spring maybe causing an intermittent short. That along with all the rust on my grounds was likely the root of the trailer wiring faults. Adjusting the brakes made it so I can lock up the trailer wheels manually. I can now get three bars to come on with aggressive pedal braking, but only while in motion. When sitting still only one bar comes on, but I think that's how its suppose to work. I only got to test drive it for 10 miles and the brakes worked well with no trailer wiring faults. My trailer season is pretty well done now so i won't know for sure until next summer. Time will tell.
    Thanks to all for your tips and suggestions.
    bespurcell likes this.

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  5. #14
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    I just got my F-150 3 weeks ago and tried towing my tt for the first time today. I was getting all the brake lights and turn signal lights, but no power, and no trailer brakes, with the same exact messages you received. After looking in my manual and checking all the pins on the harness only the lights were getting power. I also double checked a buddyís EcoBoost of the same year, original owner, never towed, it looks like Ford has left out the relay for the TT power. As well as a 30a fuse in the 21 slot. I have them on order, but after watching a YouTube video of someone experiencing and fixing it, Iím confident this will allow the pins in the harness to work, therefore giving me brakes and power to the camper batteries. I also thought right away it was something wrong with the camper wiring or connector as itís a 1997, and sat all winter. Being my truck is a lot newer, and the pin was almost new I couldnít imagine it was the truck.

    Hope that helps! Maybe you guys are just missing the fuse and relay, like me and my buddy. I can update after the parts come in if interested, but you can watch the video on YouTube here.



    Itís in the first 8 minutes of the video. And I can confirm the price of the relay is 45.00. At least here in Chicago.

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    Iíve never seen a definitive reason for this but it seems that Ford ships these with the truck but they usually show up in the glove box. I know thatís where 2 of my last 3 trucks showed up with them. The last one had them in the jack compartment but I suspect the dealer put them there. $45 seems like youíre getting hosed on the relay.
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    Ecoboost Regular SuperDave23's Avatar

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    Quote Originally Posted by Stompincc View Post
    I just got my F-150 3 weeks ago and tried towing my tt for the first time today. I was getting all the brake lights and turn signal lights, but no power, and no trailer brakes, with the same exact messages you received. After looking in my manual and checking all the pins on the harness only the lights were getting power. I also double checked a buddyís EcoBoost of the same year, original owner, never towed, it looks like Ford has left out the relay for the TT power. As well as a 30a fuse in the 21 slot. I have them on order, but after watching a YouTube video of someone experiencing and fixing it, Iím confident this will allow the pins in the harness to work, therefore giving me brakes and power to the camper batteries. I also thought right away it was something wrong with the camper wiring or connector as itís a 1997, and sat all winter. Being my truck is a lot newer, and the pin was almost new I couldnít imagine it was the truck.

    Hope that helps! Maybe you guys are just missing the fuse and relay, like me and my buddy. I can update after the parts come in if interested, but you can watch the video on YouTube here.



    Itís in the first 8 minutes of the video. And I can confirm the price of the relay is 45.00. At least here in Chicago.
    Thanks for the heads up, I did figure that one out on my first camping trip. The brakes worked, but I couldn't charge the trailer from my truck. Found the empty spot for the relay & fuse. I was up in the forest with a dead camper battery so I robbed the relay/fuse for the rear defrost since I never use that anyways. Been that way since!

    I do have an update on my original topic. Found a suspect ground connection on the trailer. The mfg ran a separate ground wire from the brakes back up to the junction box on the tongue (Good!). But they shoved it into a big ring connection with the ground wire from the 7-pin (Bad!). With a multi-meter I was able to see intermittent conductivity. Gave the brake ground wire it's own ring connector and all seems well so far. I'll know more after summer and I've gone thru a full tow season.

    I swear the trailer brakes feel stronger now too with the new connector. Before I couldn't lock up the trailer tires at all with the manual handle, but now they lock up on setting 7.
    snakebitten likes this.
    Dave
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