Trailer Wiring

[alexdrums]

Pinout diagram was posted last November, Backup light is Pin 8

The backup light signal is available in the 12-pin harness for the tow hitch. It is pin 8 (see below). The tow harness is located behind the debris cover behind the left rear wheel - just follow the tow hitch harness if you have the factory hitch installed. The factory hitch has a four blade connector, but it has a metal plate that can be removed where the connector is installed that can be removed so a 7-pin round connector can be installed. Unfortunately, there is no pre-installed wiring for a trailer brake, so if needed, you will need to install a TB and run the appropriate wiring.

So I guess the stock 4-pin harness is just the two turn signals, brake and taillights?

 

[cgriffith]

Pinout diagram was posted last November, Backup light is Pin 8

The backup light signal is available in the 12-pin harness for the tow hitch. It is pin 8 (see below). The tow harness is located behind the debris cover behind the left rear wheel - just follow the tow hitch harness if you have the factory hitch installed. The factory hitch has a four blade connector, but it has a metal plate that can be removed where the connector is installed that can be removed so a 7-pin round connector can be installed. Unfortunately, there is no pre-installed wiring for a trailer brake, so if needed, you will need to install a TB and run the appropriate wiring.

 

[cgriffith]

So I guess the stock 4-pin harness is just the two turn signals, brake and taillights?

 

[cgriffith]

Yes, the stock 4 pin is turn signals, brake and taillights. If you have a 5 pin trailer harness, it plugs into the 4 pin fine. All works great except backing up due to the missing pin. I have the kit from etrailer to go 4 pin to 5, just need to find the backup wire to slice into.

I posted pictures at 12:41pm with the dust cover off, I don't see the 12 pin harness with a metal cover. My hitch is the factory hitch and installed by the dealer, Possibly that is different if it was original factor build in the November diagram.

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[KTEL892]

So I guess the stock 4-pin harness is just the two turn signals, brake and taillights?

Standard trailer wiring colors
White Ground
Brown Tail lights
Yellow Left Turn/ Brake
Green Right Turn/ Brake

Add fifth wire
Blue Brake Disengage

 

[KTEL892]

Yes, the stock 4 pin is turn signals, brake and taillights. If you have a 5 pin trailer harness, it plugs into the 4 pin fine. All works great except backing up due to the missing pin. I have the kit from etrailer to go 4 pin to 5, just need to find the backup wire to slice into.

I posted pictures at 12:41pm with the dust cover off, I don't see the 12 pin harness with a metal cover. My hitch is the factory hitch and installed by the dealer, Possibly that is different if it was original factor build in the November diagram.

Follow the dealer installed trailer wiring, it is plugged into the 12 pin connector. If vehicles are shipped from the factory without towing package that 12 pin connector comes with a weather cap, which is removed and discarded then the trailer wiring harness to the hitch is plugged in. You could tap into the upstream wiring on Pin 8 to get backup light.

 

[cgriffith]

Thanks a bunch. I think I got it.
First pic is the opened connection where the factory harness (right) hooks into the dealer installed trailer connection (left). If you look carefully at the right side pin 8 is there. Looking at the next pic, going to the hitch, pin 8 is not an output wire (pin 8 goes in but no wire coming out). Looking at the third pic, from the factory harness, the yellow wire is going to pin 8.
So in theory, if I hook in 'upstream' to the yellow wire and use the etrailer kit 4 pin to 5 pin (12 bucks) I can back into the storage stall and backup during launch and recovery.

 

[alexdrums]

Cool. Let us know if it works!

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[cgriffith]

The factory hitch and wiring comes with a 4 connector wiring. Trailers now have 5 connectors with the 5th wire allowing the trailer to be backed up. The fifth wire overrides the solenoid in the trailer hitch. I had to stick a screwdriver in the hitch to override it and get back in the stall. I have a kit to convert to 5, but it should be wired into the backup lights. My dealer won't do it and the manual says if you monkey with the wiring you void the warranty. I'm wondering given the backup lights are LED if there is enough power for what the trailer needs. A friend said you could hook into the tail lights and just turn on the lights when you need to back up, but they look to be LED also.

any thoughts

 

[cgriffith]

Thanks a bunch. I think I got it.
First pic is the opened connection where the factory harness (right) hooks into the dealer installed trailer connection (left). If you look carefully at the right side pin 8 is there. Looking at the next pic, going to the hitch, pin 8 is not an output wire (pin 8 goes in but no wire coming out). Looking at the third pic, from the factory harness, the yellow wire is going to pin 8.
So in theory, if I hook in 'upstream' to the yellow wire and use the etrailer kit 4 pin to 5 pin (12 bucks) I can back into the storage stall and backup during launch and recovery.

IT WORKS.... I connected the wire that comes with the 4 to 5 connector kit you can find on etrailer.com to the yellow wire (upstream in the pictures post 27). I just ran that one wire near the stock 4 pin connection. I plug that wire into the trailer connection then plug in the trailer 5 pin to the stock 4 pin. I left a few inches and it tucks right in to the mount when not in use. The kit comes with a 5 pin that would require removing the 4 pin, but seems like more work.

 

[alexdrums]

Awesome! Happy Fishing!

 

[Clocks101]

Yes, back up light signal on 5 pin trailer connector energizes solenoid valve on trailer so trailer disc brakes are not engaged when reversing. (Not necessary with drum brakes on trailer)

Why would the 5 pin signal not be required for drum brakes on trailer?

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[KTEL892]

Why would the 5 pin signal not be required for drum brakes on trailer?

All of the trailers that I have had with surge drum brakes used a 4 pin electrical connector, no solenoid for reverse, I think that they call it Free Backing where the brakes do not engage in reverse. However, I believe that there some drum trailer brakes that do engage in reverse, a 5 pin connector and a solenoid would be required. Need to confirm which trailer connector you have, 4 or 5 pin.

 

[dmorgan614]

The surge/drum brakes on my trailer (2015 for a Starweld boat - Trailmaster maybe) have a manual mechanical lockout making the 5th wire not needed. I just need to remember to put the mechanical lock in to prevent surge brake activation when I back. Haven’t towed yet, but that’s coming as soon as my son and I do not need to consider distancing on Lake Erie!

 

[cgriffith]

We have had a lot of rain and cold, so have not been out in the boat lately. I will check my trailer this weekend, I do believe it is drum brakes (not disc) and it has 5 wire connector so that is why I added the 5th wire to the KIA to be able to back-up.
Go up to February 5 on the thread to see how to add the 5th pin. The part is from etrailer.com part 20036 about 15 bucks and with the wiring info maybe an hour job. IF KIA had come from the factory with a 5 pin, it would work for 4 pin or 5 pin trailers.

 

[cgriffith]

I was up at the lake and I do have disc brakes on the trailer. So 5th wire is required for backup. I had a Tahoe prior to the Telluride and it had a factory round connector that converted to 5 pin flat connector; I was unaware of all this.
Thanks to the forum, got it solved. Hope the pics help anyone else. Thanks all.

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[Mrdubean1]

IT WORKS.... I connected the wire that comes with the 4 to 5 connector kit you can find on etrailer.com to the yellow wire (upstream in the pictures post 27). I just ran that one wire near the stock 4 pin connection. I plug that wire into the trailer connection then plug in the trailer 5 pin to the stock 4 pin. I left a few inches and it tucks right in to the mount when not in use. The kit comes with a 5 pin that would require removing the 4 pin, but seems like more work.

Good morning! How did you connect the hitch wire to the yellow brake wire please?

 

[Mrdubean1]

I did the install as you described it. Thank you. I cut the yellow/back wire and connected the reverse light wire with the yellow/black.
works like a champ. Now I can back up the boat trailer.

 

[cgriffith]

FYI - for others planning to tow some. My current boat and trailer are almost 5000 pounds. I have launched and loaded several times. I have AWD and It performs better than my Tahoe that I traded in. My previous boat was about 8500 pounds and the Tahoe handled that well, however it was 2WD. I can feel the difference of the AWD launching and loading.

 

[Vlapinta]

I did the install as you described it. Thank you. I cut the yellow/back wire and connected the reverse light wire with the yellow/black.
works like a champ. Now I can back up the boat trailer.

A couple of questions as I too want to access the reverse wire for my boat trailer with surge brakes.

Is the wire yellow or yellow/black?

Why didn't you splice into the yellow on the other side of the connector?

Thanks
Paul