[SC-421]

I haven't seen much details on towing except for the standard blerbs about the 3500# (NA) and 5000# (turbo) towing capacities. I'd like to do some occasional towing but we all know there's more to towing than just a rated capacity. i.e. What's the tongue weight? Or what other asterisks are there when it come to real world towing capabilities? I did come across one review that said an electronic trailer brake was required as part of the 5000# rating. Makes sense, but does the SC have the proper wiring set up for an electronic trailer brake? I saw another video and the Hyundai rep showed an available wire harness (assumably for the electronic brake). So even if one were to get the toped out Limited SC that is rated for 5000# towing, still could not do so without a new harness? Questions. Questions...

 

[bbrendan]

Yeah. Tongue weight would be very helpful. Hope Hyundai will give that info out.

 

[JMII]

Tongue weight is covered in the manual. 10% max of full trailer weight so figure 500lbs.
Trailer brakes required for anything over 1,650lbs (seems very conservative) but follow local regulations.
The SC is wired for an aftermarket brake controller but Hyundai does not supply much information here.
For trailer brakes you need the 7 pin connector, currently only the Kia wire harness is available but its is confirmed to work.

Missing is a spec for is the trailer's frontal area.

Specific trailer brake controller info here: The Official Santa Cruz Towing Thread plus lots of other general towing information in that long thread.

The SC doesn't come with towing package. Thus to tow the full 5000lbs with an Limited AWD you need to add the following: a hitch (OEM or aftermarket), 7 pin harness (Kia S9F67-AC500) and a brake controller (aftermarket, wired or wireless). It would be nice if Hyundai could communicate all this or train dealers about such topics but apparently there is a major disconnected between the engineers that made the vehicle, the marketing team and the dealer network. Thankfully this forum has filled in the gaps in knowledge.

 

[HSC4ME]

The above and the other thread mentioned covers the basics we know so far well, but here is something I have been waiting to get posted along with the...

Missing is a spec for is the trailer's frontal area.

This is a picture of the wiring connection that plugs into the prewired Hyundai connection at the rear of the SC for trailer wiring.

This plug is the SAME for the 4-way and 7-way trailer wiring kits installed at the trailer hitch.

I want to know what each wire location function is on this plug for BOTH the 4-way AND the 7-way wiring kits to identify the differences. A picture of each with labels would be great!

 

[JMII]

I want to know what each wire location function is on this plug for BOTH the 4-way AND the 7-way wiring kits to identify the differences. A picture of each with labels would be great!

Most likely the conversion between the 4 and 7 pin functions / signals is done via that small module that is inline with the harness itself. If you go to the link I posted above about the brake controller @CaseyH reported the wiring diagram Hyundai has on file is incorrect.

Why do you need to know the differences?

 

[HSC4ME]

Why do you need to know the differences?

I have a Curt 4-way and want to know if the 4-way to dual-function 4-way/7-way can be wired into the plug itself instead of tapping into the actual wires (cleaner).

Identifying if the Hyundai 7-way simply has the additional wires added to the plug would be key to determining which wires lead to the front of the vehicle in the Hyundai wiring. I don't think the 7-way functions are in the small computer module. I would expect trailer brake signaling is coming from the front of the vehicle where the hard wired controller plugs in, but don't really know yet. Once known, I can check all the signaling at the rear plug and match it to the 7-way.

Do you know what the Blue, Yellow & Black wires are? I believe the White is a local ground wire. Haven't spent any time researching it yet...

ADDED:
Looked them up on the Curt site:

Using 12 gauge (minimum) wire and butt-connectors, connect the remaining wires to the appropriate functions as listed below.

Yellow - Auxiliary or back-up lights
Blue - Electric brakes
Black - Positive power (+) with appropriate inline fuse

Confirm proper function with a test light or by using a properly functioning trailer. Secure any loose wires by using cable ties or equivalent product.

= = = = =

Best guess is the Hyundai/Kia 7-way has all 4 of those wires coming from the front of the SC under the dash, thus should correspond to plug connectors at the rear of the vehicle.

 

[JMII]

Why not just use the 7 pin harness and get a 7 to 4 converter? Guess I am still not understanding the end goal here

 

[HSC4ME]

Why not just use the 7 pin harness and get a 7 to 4 converter? Guess I am still not understanding the end goal here

Already have a 4-way. That's all Hyundai is installing at this time. Why waste $179?

 

[HSC4ME]

Just found the Curt #57102 4-way to Dual-Function 4-way/7-way WITH BACK BEEPER BUILT IN on the Curt site.

 

[HSC4ME]

 

[HSC4ME]

If the hard wired controller is at the front of the vehicle under the dash, then the electric brake signals are coming from there to the 7-way trailer hitch plug at the rear. If the Hyundai/Kia 7-way harness takes care of that, then it must have the needed wires within that harness and they transfer to the trailer hitch plug through THE SAME PLUG ON ALL HYUNDAI WIRING that is pictured in post #4.

I'd like to know what plug holes those are in the Hyundai plug on all Hyundai SC's. I'd rather add wires to the plug I already have, then tap into wires if I don't have to.

NOTE: If you exclude the local ground and reverse light wires, all that is needed to run electric brakes and accessories is the Blue - Electric Brakes wire and the Black - Positive Power wire. All the other lighting is already taken care of with the 4-way computer module on your existing 4-way hitch plug (if you already have one).

 

[CaseyH]

If the hard wired controller is at the front of the vehicle under the dash, then the electric brake signals are coming from there to the 7-way trailer hitch plug at the rear. If the Hyundai/Kia 7-way harness takes care of that, then it must have the needed wires within that harness and they transfer to the trailer hitch plug through THE SAME PLUG ON ALL HYUNDAI WIRING that is pictured in post #4.

I'd like to know what plug holes those are in the Hyundai plug on all Hyundai SC's. I'd rather add wires to the plug I already have, then tap into wires if I don't have to.

NOTE: If you exclude the local ground and reverse light wires, all that is needed to run electric brakes and accessories is the Blue - Electric Brakes wire and the Black - Positive Power wire. All the other lighting is already taken care of with the 4-way computer module on your existing 4-way hitch plug (if you already have one).

Not sure of the difference between the 4 and 7 pin harness and if the7 pin harness module is doing anything extra. As far as the documentation goes; Hyundai has corrected it, and even emailed me the updated documentation and issued me a refund for the service portal access I paid for. Red outlines added by Hyundai highlighting the corrections:

 

[HSC4ME]

Thank you very much for that. I had no idea the Hyundai manuals had errors in them regarding the trailer hitch wiring.

It "SEEMS" to me one can convert their existing 4-way Hyundai or Curt harness to a 7-way without having to buy a new Kia 7-way if they are so inclined (Much "easier" to put the money out for they Kia 7-way or future Hyundai version though, but you will still have to wire up the Electric Brake Controller under the dash). One can simply cut off the 4-way connector that goes to the trailer and rewire it to a 7-way.

I just ordered up a Curt 4-way and 48" brake light bar for my brothers SC. I will use this new information to wire his reverse light up without tapping into an existing reverse light wire and see if it works.

On the surface it "APPEARS" this is how the Curt 4-way to 7-way (or Dual-Function 4-way/7-way) should be wired:

CURT Yellow - Auxiliary or back-up lights = HYUNDAI 8. Y/B - Back-up lamp: ICU Junction Block (IPS10)

CURT Blue - Electric brakes = HYUNDAI 7. Y - Trailer Controller

CURT Black - Positive power (+) with appropriate inline fuse = HYUNDAI 12. L - E/R Junction Block (FUSE TRAILER2) -OR- HYUNDAI 1. W - E/R Junction Block (FUSE TRAILER1) NOT CLEAR WHICH ONE

CURT White (ground) = HYUNDAI 6. B - Ground (GF03)

All this will have to be tested appropriately for proper function and will still require an Electric Brake Controller to be wired up under the dash at that 4-way connector. At least we now have the wire connectors labeled.

Note the "SEEMS" and "APPEARS" because I have NOT done this yet. I also don't know what the difference is between the HYUNDAI 1. and 12. are. My best "GUESS" would be that they are both positive HOT wires; 1. is meant for the trailer computer module that controls the brake/turn/flasher lights and 12. is meant for the 7-way trailer positive HOT wire.

I will post up what my wire testing indicates when I install my brothers SC light bar...

 

[JMII]

If you just want to wire up a light bar then get the 4 way and your golden. But if you plan on towing anything I would get the 7 way - this way its future proof... you can connect to whatever trailer you encounter.

Trying to convert the 4 pin to 7 pin just to save $110 ($150 factory part vs $30 Curt adapter + $10 in misc connectors / wires / heat shrink) seems penny wise but pound foolish IMHO, especially once you factor in lying under the vehicle figuring this all out and connecting things up. Its certainly possible to accomplish this, so if you enjoy such projects go for it.

 

[HSC4ME]

If you just want to wire up a light bar then get the 4 way and your golden. But if you plan on towing anything I would get the 7 way - this way its future proof... you can connect to whatever trailer you encounter.

Trying to convert the 4 pin to 7 pin just to save $110 ($150 factory part vs $30 Curt adapter + $10 in misc connectors / wires / heat shrink) seems penny wise but pound foolish IMHO, especially once you factor in lying under the vehicle figuring this all out and connecting things up. Its certainly possible to accomplish this, so if you enjoy such projects go for it.

Once again, I have a 4-way already and a light bar. There is no way I'm buying a Hyundai OEM over priced 7-way and having to spice into it to connect the 4-way light bar plug at the rear. It is 100% easiler and cheaper to simply plug in a Curt 4-way to "Dual-Function" 4-way/7-way to your existing 4-way for this application (and I would argue for only a 7-way too, if you already have the 4-way). The 4 additional wires are only: reverse lights, electric trailer brakes, positive hot wire and ground.

If Hyundai had a plug and play harness WITH plug and play controller (which they do not offer), then that would be great for those that don't already have a 4-way in the back and don't plan to run a light bar. You wouldn't/shouoldn't need a professional to plug the wires in.

To each their own application. This simple wiring is not rocket science. All owners need is correctly labeled plug knowledge. None of this should be presenting anyone problems once owners know what connections are what.

If someone doesn't understand how to wire those added 4 wires to make a 4-way into a 7-way, then they likely won't know how to wire the 4 wires at the front once they buy the Hyundai 7-way and an aftermarket controller. That has to be wired buy the owner no matter what rear harness you use.

I highly recommend those that get confused regarding proper wiring for their trailer brakes hire it out to a professional and get a warranty on the work. Even the professional can't do the job until he knows what all the Hyundai SC wires are for.

This stuff is a cake walk for the trailer professionals. Don't think once you buy the expensive Hyundai 7-way harness for the back and plug it in that you are done and ready to tow with trailer brakes.

I'm tapping out on this electric trailer brake stuff. Best of luck folks.