Trailer Surge Brakes Vehicle 5 Pin Wiring Harness

D

Daniel1980

Member
Jun 29, 2021
88
Boat Info
Sea Ray 175 Sport
Engines
Mercruiser 3.0
Was hoping I can call on any experiece with a 5 pin wiring harness. I have a 4 Pin and ordered the 4 to 5 pin harness to operate the actuator to release the surge brakes when backing up.

It comes with an extra blue wire that I am supposed to splice into my reverse light to operate the brake release. I am concerned that the vehicle light module will not like this jenky set up and throw an error light. Does anyone have any experience doing this? I really don't like interfacing "adapters" but outside using the manual "key" to disable the brakes when backing down the ramp, I'm not sure what else to do. What if I am trailering and need to back up on the road? Jumping out in potential traffic to insert the key sounds like a bad idea and real possibility.
 
Depending on your local regs, yes, you may be able to delete the braking system. However, since you have it, probably your best bet is to get a 7-pin installed on your vehicle. Then use a 7-to-5 adapter. The 7-pin will allow you to do anything you want in the future.

Whether your vehicle's computer will like a splice job or not depends on the vehicle and the splice job - only you can answer that. Older vehicles won't care at all - some newer ones can be quite picky. Some will even error based on LED or incandescent and what they're "set" for.
 
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Thanks Lazy Daze.

I've seen the 7 pin. Thinking I might need some kind of controller. The 4 to 5 is "universal" and I really hate tapping a wire....was hoping for a harness splitter. The surge brakes work great. Going from 2500lbs no brakes, to 4000lbs with brakes....it is easier to to tow the heavier boat.
 
You won't need a controller. You'd only need to add that if you end up with, down the road, electric brakes. For now, you just need the 7-pin receptacle.

FYI, your signature still says 175 Sport :)
 
You should be able to buy the pigtail for your truck that plugs right into the factory harness. Can't say for sure though that it would have the blue wire connected to the reverse lights though. My understanding is that is what activates the trailer brake bypass. My truck had it all installed from the factory so I just had to buy the 5 to 7 adapter
 
Wait, what? Every pick up I have owned from my 84 to my current 2004 has always had a 7 pin plug. And every one of them had the reverse lights wired in. As well as a trailer brake, whether I had one installed or not. Left, Right, Stop, Running, break, Back up and power. And an adapter can be had to convert to anything else needed. I have one for all of them because I never know if I will ever need one. I had a 94 and then a 95 Chevy and that was the first years that were plug and play with the wiring harness to plug.

I'm not sure of what your using to pull with, but since OBD2 and "fly by wire", there has been a plug and play harness.
 
Some trailer couplers have a metal pin or plate that can be inserted to disable the brake actuator. My 2019 SeaRay had that pin attached to the tongue with a steel cable. When you are at the ramp, or your driveway, and you need to back up, simply insert the pin. When you want to drive forward and need the brakes, just pull it out.
 
GypsmJim said:
Some trailer couplers have a metal pin or plate that can be inserted to disable the brake actuator.
Click to expand...
@Daniel1980 brought up a very real possibility in his first post that, in the event he needs to back up while out on the road, he could find himself in a dangerous situation by having to jump out and install the pin.
 
Daniel1980 said:
The 4 to 5 is "universal" and I really hate tapping a wire....was hoping for a harness splitter.
Click to expand...
Are you not able to find a splitter for your tow vehicle? Most trucks since the mid-90's will have the means to break into the harness near the back bumper. Dorman has a pretty good parts finder, and most of their products can be found in Amazon and eBay.
 
Nater Potater said:
Are you not able to find a splitter for your tow vehicle? Most trucks since the mid-90's will have the means to break into the harness near the back bumper. Dorman has a pretty good parts finder, and most of their products can be found in Amazon and eBay.
Click to expand...
+1 on this
except I've used Hopkins parts in the past. If your tow vehicle didn't come with a factory installed 7 pin receptacle then you can use one of the adapters that Hopkins or Dorman sells. They are vehicle specific and you don't need to do any splicing. Using the emergency backup pin every time that you need to reverse would be a major pain.
 
My 2011 Metalcraft trailer doesn't have a back up pin or latch. As long as I'm not backing up a hill it's good. I need to find something other than a C clamp on the coupler. Seriously thinking about the electric over hydro. Sure would make it easier.

So for helping purposes, what are you working on.
 
Another option would be to splice the backup wire in to the tail light wire temporarily on the trailer. If you are trailering during daylight hours you would be able to turn on tail lights to disable the trailer brakes. This is a bad and red neck idea. However it is easy and quick if you are just needing a quick move at a boat ramp or parking lot.
 
I agree with you that depending on the manual lock-out pin for regular use is a no-go. When I used to live in North Idaho and trailered over some steep country we found that on long down grades using the transmission to do a lot of the braking work, the surge brake system would apply the trailer brakes over long periods and overheating was a problem. What most guys did, including myself, to alleviate this was to remove the back-up light connection from the solenoid wire and install a toggle switch on the dash of the truck that provides 12V to the solenoid on demand. With that set-up you can dump the brake line pressure anytime you want by flipping that switch, which opens the solenoid valve, dumping brake line pressure back to the master cylinder reservoir. This set-up would not require you to tap into your vehicles wiring harness and give you complete control of your solenoid. I would recommend installing a guard to prevent accidental activation of the switch, which would cancel your trailer brakes. I am attaching a link to show a guard. This one is from China but you can find better ones made in USA. Make sure you get one that will kill the switch if the cover is closed so you can't forget it.

https://www.amazon.com/Nilight-9001...7QKFD7Z7/ref=psdc_15734681_t1_B07VNDPZ9W?th=1
 
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