4 pin to 5 pin connection question when double hauling??

[7lazy77]

just recently acquired a new"er" boat & the trailer has surge brakes with a 5 pin harness. My tow vehicle has both a 7 pin & a 4 pin connection, so I am not worried about connecting to the tow vehicle since I can just use a 7 pin to 5 pin adapter & problem solved. However, there will be ocassions when I want to hook the boat up behind my 5th wheel camper (double-tow) & my camper ONLY has the 4 pin harness. Do I have to purchase the 4 pin to 5 pin adapter & splice in to my camper brake light, or will I be alright just plugging the 4 pin into the 5 pin??? Please correct me if I am wrong, but I should be alright since I will NOT be doing any backing up when the boat trailer is connected to the 5th wheel trailer, so I will NOT need to worry about the reverse lockout? Will I still have boat trailer brakes when i am hauling down the road using the 4 pin plugged into the 5 pin harness? Any help is appreciated.

 

[NYBo]

Yes, your surge brake will still function without the 5th pin.You just won't have the reverse lockout. You DEFINITELY don't want to hook the 5th pin to the camper's brake light. That would lock out the surge brakes every time you hit the brakes!

 

[smokeonthewater]

Yes surge brakes do not require ANY electrical connection to operate.
The only use for the 5th wire is reverse lockout...
Tha said I would add the reverse wire to the camper....

You may not plan to back up but coming from someone who tripple tows all the time there may well be a time that you need to back up if just a few feet..... IE, oops this is a dead end and I don't have quite enough room to make this turn.

A little effort now could save you from having to drop your trailers and manhandle the boat in the middle of a busy intersection so you can back up 15 feet.

 

[UncleWillie]

The worse case with trying to back up a triple tow without unhitching anything would be to have to jump out and engage the MANUAL Lockout on the Surge brakes.
The effect will be the same as having the Fifth Pin wired to the Reverse light signal. Just not as convenient.

And I'll repeat it here again....
The signal to the 5th Pin is the REVERSE Light Signal. Not the Brake Light Signal!
This DISABLES the Surge Brakes when backing up.
If you were to attach it to the BRAKE Light Signal; You would DISABLE the Surge Brakes every time you applied the Brakes.
You would never have any brakes except when trying to back up when you really don't want brakes.

 

[Outsider]

Buy a 7-pin to 4 and 5-pin adapter, doesn't matter then which trailer you pull. Your 7-pin should be factory wired correctly, who knows about the trailers. Like always, verify what your wiring does before pulling out ...