Tow 7 Pin Fuse

[Muskyhunter]

Hi- looking to see if anyone can provide insight to an issue I'm having. I have a 2010 1500 and had my boat out this past weekend. First couple trips of the year had no issues but this past weekend I went to back up and my trailer brakes locked up. Did quite a bit of troubleshooting and found that I have no voltage at the Electric Brake pin of my 7 Round plug for the boat when truck is in reverse. This pin provides the boat trailer solenoid power to not engage the brakes while backing up. All of the other pins have power at the correct times (turning, running lights, brake lights, etc.)

I pulled every fuse in the main fuse box in the engine compartment and not a single one was blown. Is there an additional fuse box anywhere on this truck? Or a fuse inline somewhere specifically for the electric brake of the 7 pin receptacle? I pulled the plug receptacle from the bumper and checked that all the connections are solid, no wire is visibly compromised. I'm at my wits end trying to find this gremlin. I had a Durango previously and there was a fuse specifically for the electric pin and I only know as I had this same exact issue happen with that vehicle. With my 1500 I've never had this issue the past 8 years. Thanks for any assistance.

 

[drdarrin]

Wow! Never heard of electric brakes on a boat trailer before. And on a conventional trailer, the brake circuit is only hot when applying the brakes, the opposite of what you describe. Being in reverse or drive should make no difference.

But, that circuit is typically protected with a circuit breaker because of the amount of current it can draw. On your model truck, I’m not sure where you will find it.


Sent from my iPhone using Tapatalk

 

[Demon-HeMi]

Wow! Never heard of electric brakes on a boat trailer before. And on a conventional trailer, the brake circuit is only hot when applying the brakes, the opposite of what you describe. Being in reverse or drive should make no difference.

But, that circuit is typically protected with a circuit breaker because of the amount of current it can draw. On your model truck, I’m not sure where you will find it.


Sent from my iPhone using Tapatalk

x2 all the way, ive never heard of the trailer brakes not being triggered by a + signal...

to me it sounds more like the problem is in the trailer and not the truck, something in the brake drums on the trailer is probably rusting out and catching in reverse, and to be honest if they are locking up in reverse then they are probably dragging going forward...

to check your truck if its functioning properly, put a test light at your 7 pin and see if it gets power to the trailer brake output when brakes are applied, if you do then your truck is working fine and the problem is in the trailer.


also you may check the emergency brake on the trailer for any kind of damage or corrosion, and by that i mean the one that is triggered should the trailer become detached when rolling down the street, its usually engaged by a little steel cable being yanked out

 

[David H]

I also have that type of boat trailer. Mine is a 5 pin flat so I use an adapter for the 7 pin round receptacle on my truck. The 5th pin is for releasing the trailer brakes when backing.

That feature may be tied to your backup lights. Backup lights working? Otherwise I would guess fuse M52

 

[Jimmy07]

Every boat trailer with surge brakes that I’ve seen uses the reverse/backup light pin (center pin on the 7-way) to power the solenoid to disengage the surge brakes, not the electric brake pin.

 

[Muskyhunter]

Thanks for the feedback thus far. And yes, my bad, they are surge brakes not electric. After calling around a few places today, the brake lock out for reverse is tied into the backup lights. And the backup lights on my truck are working so my guess is wherever the 7 pin is tied into my backup lights is where the issue may be. Not sure if Dodge uses an quick clip to tie into and if they have a fuse at that juncture.

My last option is I buy a 4 flat to 5 flat connector and use my 4 flat with a reverse light splice.

This is driving me nuts and I may have to suck it up and take to the dealer :-(

 

[Demon-HeMi]

Thanks for the feedback thus far. And yes, my bad, they are surge brakes not electric. After calling around a few places today, the brake lock out for reverse is tied into the backup lights. And the backup lights on my truck are working so my guess is wherever the 7 pin is tied into my backup lights is where the issue may be. Not sure if Dodge uses an quick clip to tie into and if they have a fuse at that juncture.

My last option is I buy a 4 flat to 5 flat connector and use my 4 flat with a reverse light splice.

This is driving me nuts and I may have to suck it up and take to the dealer :-(

I think there is actually a reverse light fuse for the trucks trailer system

 

[Muskyhunter]

Thanks for the note. I’m going to call the dealership today and see if they can provide me any details on that fuse. I feel as it might be the connection from the 7 pin plug to the reverse lights as my truck backup lights still work. But if there is a fuse between the 7 pin plug and where it is tied into the reverse light power, that is what I feel I’m looking for.

 

[David H]

Thanks for the note. I’m going to call the dealership today and see if they can provide me any details on that fuse. I feel as it might be the connection from the 7 pin plug to the reverse lights as my truck backup lights still work. But if there is a fuse between the 7 pin plug and where it is tied into the reverse light power, that is what I feel I’m looking for.

Let me know what you find. Just brought my boat home from storage and the brakes locked up backing up my drive. Same issue as yours. Can't find my multimeter. Time for a cocktail.

 

[David H]

Found the Fluke. No power on the center pin. Blown fuse under the hood. Some kind of 20 amp J case fuse that's not at the local store. Figures. Looks like Amazon.

 

[crash68]

Every boat trailer with surge brakes that I’ve seen uses the reverse/backup light pin (center pin on the 7-way) to power the solenoid to disengage the surge brakes, not the electric brake pin.

Just a side note, there are free-backing brake assemblies for surge brakes. You don't need a release solenoid for them.
When I rebuilt the brakes on my boat trailer, I found out all about them. The dealer built the trailer with two right side brakes, and the one on the left side wasn't free-backing.

 

[Muskyhunter]

No power center pin, I am now very familiar with this. I spent over 5 hrs. this weekend following ground wires, tow harnesses, etc. from the engine compartment all the way back to my trailer brakes looking for a short. Nothing. Fuses all good. Had 3 different tow vehicles hook up and all the same problem. After my 5th adult beverage and severe frustration I finally figured it out. I use a 7 round to 5 flat extension to reach the boat plug. The 7 round center pin had come unscrewed and not making solid connection. Looking back I should have spent a few more minutes evaluating this connection as I had to really look hard to notice the center pin had become loose. Would have saved a ton of time!