Installing a 7-pin trailer connection on a '99 XLT

[Homerexplorer]

I have a '99 Explorer XLT that did not come with the towing package. I have installed a hitch, verified the tranny cooler and need to install a 7 pin connection for a boat trailer. I don't know why the trailer is using a 7-pin (no electric brakes, just surge brakes, back-up lights maybe?) but it really doesn't matter. I have identified the pigtail under the driver's side tailight for the 4-pin trailer connection. My plan was to buy the 4 pin connection for this pigtail and then buy a Hoppy wiring harness to go from the 4 pin to the 7-pin. I was then going to splice in the necessary wires in the taillamp assembly for the back-up lights (back-up hot wire). Any other suggestions?

I also noticed a 6 pin pigtail under the bumper of the passenger side taillamp. Does anyone know what this is for? I tested it quickly and it did not seem to be for the signals. Any help would be appreciated as the Ford dealer had absolutley no idea about any of this.

 

[Doug]

You really only need a 7 pin connector if you have trailer brakes and back up lights. There is also a pin for 12v constant if you need it. If you need to wire anything up this is a good website for wiring up trailer connectors.
http://www.etrailer.com/faq/wiring.asp

 

[Homerexplorer]

5th wire

It's my understanding that the 5th wire (reverse/back-up) disables the surge brakes. Is this correct? The 1st trailer I looked at had a 5-pin but the one I'm looking at now comes with the 7-pin. I don't plan on connecting the 12V source or the electric brakes, as I don't have a need for them.

 

[Doug]

if it have surge brakes there are no electrical connections. I used to pull a trailer with surge brakes and if the brakes ever locked up I'd just drive the opposite direction i was going and they would generally unlock.

 

[SplashMan]

From the sounds of it I would just buy a 7 to 4 adapter and use the 4 prong you have.

http://www.etrailer.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=E&Category_Code=A

 

[gijoecam]

There are some surge brake systems that use a back-up dump solenoid or lock-out solenoid to allow you to back the trailer up a hill. Without it, the harder you push it, the tighter the brakes are going to lock, and you end up skidding the trailer up-hill. It's quite possible that this system is one of those. The only way to know is to speak with the trailer owner/manufacturer/assembler/builder that knows.

For basic lights, just pick up a 7-4 adapter at the local trailer shop.

-Joe

 

[stretch]

This is the outlet I have mounted in the rear bumper of my X. Has both the 4 and 7 prong hookups. Plus I don't have to worry about losing any adapter (been there before ). I bought it from WalMart for $20.

 

[Homerexplorer]

Thanks for all of the input. The trailer manufacturer (Prestige) got back to me and was very helpful. GIjoeCam was exactly right - there is a back-up solenoid that disengages the surge brakes when the back-up lights are on (5th wire), allowing you to back up an incline. Thanks again.