NCV3 OEM Trailer Harness install


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Searching this forum yields mixed results regarding this and the more I searched the more I found conflicting information and partial write ups without conclusions. Frustrating I know you have all been there.

I attached a PDF of the install directions and posted them here. I didn't include any pictures :idunno: Even without pictures I think this should be a sticky in the how to thread based on how many threads on this site reference installing trailer hitches (dozens upon dozens)

Successful OEM trailer electrical harness installation!
My 2011 2500 NCV3 Did not come factory with the trailer hitch, as many other
threads point out the most cost effective way to get a factory hitch is to order it…
well I like my rig and I didn’t want to hack in some after market harness so I went
with OEM.
The following part numbers correspond to the requirements for installation.
020-545-40-26 Plug socket List $73.60 Net $54.00
906-440-00-64 Electrical Harness List $264 Net $240.00
169-545-56-32 Trailer control module (I found a used one on ebay $70 shipped)
Unk part number – 80 amp mini ANL fuse installed prefuse block
Unk part number – quantity 2 nuts for prefuse box I had one already existing and I
found the other one on a stud under the drivers seat not doing anything…
906-545-12-40 Bracket (I didn’t purchase or install this but it should be the bracket
that holds the plug socket at the rear of the vehicle)
013-545-76-26 MCP2.8 .5-1.0mm contact spring (directions call for a 014-545-82-26
MCP2.8 1.5-2.5mm but it was to big to fit so I stepped it down to the previous)
***Software update from dealer*** $150 hour labor charge (took them 3 hours to
figure it out, they had to go line by line to find the proper accessory to activate)
According to the author if this thread you can order an entire kit which comes
complete with the OEM hitch as well. I cannot speak to that because it’s not what
I did but you can view his thread and pictures of the process here. There is no
conclusion as to his success.
If you are attempting this you should have some decent knowledge of tools and workmanship I will try not
to be vague but most of this was very self-explanatory… Start to finish will all parts and several beers on
hand I would say this is at most a 90 minute install
The wiring harness has a female plug socket on one end with a long attachment of wire to the other end, the
wire appears to be long enough for a 170 or a 144, I installed on my 144 and had several loops at both the
front and back of the van. The female plug and the plug socket go together at the back of the van.
Remove the drivers seat and fish the female plug down through the rubber boot in the floor. Route the cable
however you deem appropriate to the back of the van. I left about 24” extra at the back and there is easily
just as much looped under the seat. Secure appropriately.
Now you are left with 5 bundles of wire
1 Wiring harness
2 CAN bus line
3 terminal 54 cable
4 terminal 15 cable
4a plug contact terminal 15
5a cable bridge terminal 30
5b plug contact terminal 30
5c plug contact terminal 30
6 terminal 30 cable
7a cable bridge terminal 30
6b plug contact terminal 30
8 lines for terminal 31
9 trailer brake control unit line.
10 trailer module plugs.
Cable number 6 gets routed to the battery prefuse box. (disconnect the battery) remove the black battery
cover unhook the prefuse block from the positive terminal. Insert the 80amp mini ANL fuse then attach and
tighten using nuts.
Cable number 5 has 3 spade connectors at the end, one bridge and two that look the same. The bridge
connects fuse 14/15 then red/black goes into 15 and red/yellow goes into slot 14. There are red tabs on the
fuse blocks they need to be slid so they are unlocked before jamming them in there don’t forget to relock
them. By looking at the rest of the wires hooked up this should be fairly self-explanatory process.
INSERT 20amp fuse into 14 and 25amp fuse into slot 15
Cable number 4 has only one connection to be made. It plugs into slot 4 which already has power supplied
from the rest of the fuse block and inser 7.5 amp fuse into slot 4
Cable number 7 has two connections. 7a goes into slot 30 it is providing power to 7b, 7b red/yellow also
goes into slot 30 don’t get them mixed one is power supply through the fuse. Use a 30amp fuse in slot 30
Cable number 8 is the ground it should be obvious where to attach this, I had 3 other ground cables on a
stud that I attached it with.
Cable number 9 is the trailer brake controller plug… ignore it unless you are installing a brake controller. If
you are installing a brake controller reference Thread https://sprintersource.
Plug in the sockets to your trailer module, they only go one way.
At this point you should be done under the seat. Route the 2 remaining cables (2 & 3) out the inside of the
seat with the power cable because they will be going up under the dash. Secure everything under the seat
and feel free to reinstall if you are confident with your work.
Route cables 2/3 as appropriate to get up under the dash, cable 2 has two connections to be made to the
CAN bus at the A pillar, cable 3 violet/black is attaching to the SAM.
2-pin brown and brown/red gets pugged in on CAN bus
Detach the multiplug from the SAM from slot C1. Attach plug contact to line for terminal 54 and fit into
contact cavity 15 of multiplug



2013 144
Thanks for the work! The site has a nice video on installing an NCV3 hitch wiring as well.

Sent from my iPad using Tapatalk


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From what I have seen of e-trailer videos is for all aftermarket acccessories. The curt and drawtite hitches are super simple to install but they are bulky and you lose some ground clearance about 3-4". Any after market trailer connection won't properly talk to the ECU so you miss out on all the fancy ecu driving assist items that come along with towing a load.


Note to self; stay in der DZ.
From what I have seen of e-trailer videos is for all aftermarket acccessories. The curt and drawtite hitches are super simple to install but they are bulky and you lose some ground clearance about 3-4". Any after market trailer connection won't properly talk to the ECU so you miss out on all the fancy ecu driving assist items that come along with towing a load.

For example, Parktronic, if so equipped, will be deactivated when the trailer is plugged-in. Excellent job Owen, thanks!


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Just completed 1800ish miles flat towing a 1997 Jeep Wrangler behind the sprinter. Any reservations I had about spending the money on the OEM system were put to be while towing. It was as if I wasn't towing anything hills curves everything handled like a dream. There were a few times going down tight hills that the jeep was trying to push the back end around a corner the computer took over and handled the braking for me a few different times.

Well worth the investment for an uneventful drive.


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When performing this install I installed a used trailer control module, everything worked great up until today. I hooked up to a trailer with a 7-pin connector, I have inconsistent turn signals which are weak, and when I turn on the headlights I lose my turns all together.

After investigating at the trailer control module pin out I have a consistent right turn, but its weak and irregular. I have no left turn coming out of the module (I had one earlier) but when I apply the brake I get normal left and right turns... I think this trailer control module took a poop on me...

Anyone have any other suggestions before I drop the $$$ on a new one? I need this resolved by Wednesday... feedback would be stupendous.


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So I instinctually blamed the van as the culprit... after doing way to much reading I realized that you can't test the module with a test light or a volt meter because there needs to be resistance in the line telling it there is a trailer needing the signal. So i hooked up to a few other trailers and found one that worked like it should so I started double checking the wiring on the trailer I need to haul and wouldn't you know!? Someone wired that crap all backwards and had a few missing connections I have no idea how it ever worked before.

New rule for me, the van is perfect everything else is broken.


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I have a SAM with X1, X7 etc. connectors labeled. Instructions say C1, also received another set of instructions, which references H3 connector. I have neither, I have these X connectors. Where does terminal 54 go?


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I found the C1 (instead of the SAM it is on the K40/9 panel in the middle).
Now comes the confusion. Is it H3 or C1. Since, I have not found any H3 yet, I would go with C1.



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