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Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Item # 33855
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Custom Fit Vehicle Wiring

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Hopkins Converter Custom Fit Vehicle Wiring - 33855
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Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring - no cutting or splicing required. 1-636-306-4830 to order Hopkins custom fit vehicle wiring part number 33855 or order online at Free expert support on all Hopkins products. Guaranteed Lowest Price and Fastest Shipping for Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (38)
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Hopkins Custom Fit Vehicle Wiring - 33855

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • Converter
  • Hopkins

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring - no cutting or splicing required.


  • Provides a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Connects quickly and easily - no cutting or splicing
    • Locate connection points in rear cargo area
    • Plug in connector
  • Includes a tail light converter to ensure that your vehicle's wiring matches that of your trailer
    • Powered module pulls power directly from battery to avoid overloading vehicle's electrical system
  • Protective connection terminals resist corrosion
  • Comes with dust cap for 4-way flat connector, cable ties, and terminal grease packet for electrical connections


  • Maximum amperage:
    • Turn lights: 8 amps per circuit
  • 90-Day limited warranty


This custom-fit T-connector plugs into your vehicle's wiring harness, which is located in your rear cargo area on either the driver's or passenger's side. You will have to remove some interior paneling to access this harness.

Once installation is complete, the 4-way flat connector will be stowed in your rear cargo area.

It is recommended that you use a small amount of grease on all electrical connections - the plugs on your automobile and the 4-pole connector itself - to help prevent corrosion.

Powered Tail Light Converter

A tail light converter is built into this T-connector. This converter is a battery-powered unit that bypasses the electrical routes that are used by a basic wiring harness. As a result, there is virtually no draw on your tail light circuits.

Because most trailers run on a two-wire system - wherein the brake and turn signals are carried on one wire - the separate brake and turn signals from your vehicle's three-wire system need to be combined so they are compatible with the wiring system of the trailer. This converter combines the brake and turn signal functions of your automobile so that they run on one wire to properly activate your trailer's tail lights. Note: This will not affect how the tail lights on your vehicle operate.

43855 Plug-in Simple Hopkins T-Connector with 4-Pole Trailer Connector

Installation Details 33855 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Reviews

Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 33855

Average Customer Rating:  4.8 out of 5 stars   (38 Customer Reviews)

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring - no cutting or splicing required.

2006 Subaru Outback Wagon

Quick shipment, right part! I'm very happy with my purchase. I've been wanting to tow a small trailer with my Outback, but because I couldn't connect lights, all the hitch ever was used for was to hold a bike rack. Then I purchased this very easy to install OEM-style trailer light harness, and I'm ready to tow!

After a year, the wiring harness is still working perfectly. It was a good purchase!
Robert - 05/09/2022

2009 Subaru Outback Wagon

Trailer Wiring Connector for a 2009 Subaru Outback1. Required tools:
a. Phillips head screwdriver
b. Flat head screwdriver
c. Needle-nosed pliers
d. Knife
e. Small prybar
2. Remove the left side storage panel door, exposing the auxiliary equipment plug and storage compartment.
3. Remove the spare tire floor hatch.
4. Remove the foam storage tray covering the spare tire.
5. Remove the left floor panel by pulling up with a handhold near the tailgate and another between the two white plastic squares. The floor panel is held in place by two hidden bayonet pin clips that protrude into two white plastic squares.
6. Remove the left foam floor panel by pulling out a single pin clip in the non-foam area near the tailgate and pulling out the white plastic squares, which have bayonet pin clips on their bottoms.
7. Search the small crack between the floor and the interior side panel for the wiring harness. The wire may appear as a loop with a pink tape.
8. The connector is taped to the main harness wire just below a wire clip. Pull on the loop until you stretch the blue tape and release the connector. The crack is too narrow to insert your fingers and there is no access from above. Try pulling on the loop using the end of a screw driver. Pull toward the front of the car. If you feel uneasy about applying too much force, then use the following steps.
a. Pry off the small plastic cover in the center of the rear left cargo ring, exposing a Phillips head screw.
b. Remove the cargo ring screw. Pull on the cargo ring, it should pop out.
c. Using a small prybar pull the interior panel out enough to get a slant view of the connector which should be located just to the right of the cargo ring mounting bracket.
d. Cut the blue tape and pull the connector loop out through the crack at the bottom of the interior side panel. If you cannot cut the tape then you must partially remove the interior side panel.
e. Pry up the left end of the liftgate threshold. It is held in place by two hidden bayonet pin clips about 2 and 4 inches from the left end.
f. Temporarily block up the end of the threshold with a wedge.
g. Using the prybar and screwdriver, pull back the edge of the interior side panel enough to expose the connector. Wedge the side panel open.
h. Reach in with the knife and cut the blue tape. You may have to duct tape the knife to a stick to reach the connector. Pull the connector loop out through the crack at the bottom of the interior side panel.
i. Refit the interior side panel and threshold. The hard part is over.
9. Apply a small amount of electrical grease to the male end of the connector to help prevent corrosion and push the connector ends together.
10. If not attached, grease and attach the trailer plug and wiring harness to the converter box.
11. Mount the converter box using the supplied double-sided tape, screw or zip-ties.
12. Route the wiring harness along the crack to the back of the vehicle.
13. Check the harness by plugging into a properly wired trailer. Test all functions with the engine running.
14. Replace the foam floor panel, the left floor panel and the left side storage panel door.
15. Replace the foam storage tray covering the spare tire and the spare tire floor hatch.

2007 Subaru Impreza

Fit great and easy install !
I have
a Subaru Impreza Wagon 2.5i 2007.
You can easily access to the plug without removing the back light cover part. To see the plug, remove the small styrofoam storage part on the helper side. (not removed on pictures) . The wiring harness module box can be inserted into the molded styrofoam part without drilling anything. The trailer wiring can also be stored under this small storage door.

2003 Subaru Forester

Mice ate my trailer wires and I didn't check for shorts before connecting the wire harness, which shorted out. I had gotten it from a Subaru dealer and it was supposedly "genuine Subaru parts" with the logo and all. I cut it open and guess what? The circuit board says "Hopkins". Why pay big bucks at the dealer? You won't do better than getting the same thing for less than 1/2 at!


The box was damaged and wire package was torn open. Haven't installed yet


One of the beat online buying experiencess yet...quick. shipping, good feedback, product was exactly as described and I installed it without a "hitch". Thanks etrailer!


These hitches and electrical systems work awesome for older Subarus. We are fly fishing guides and the hitch pulls a drift boat and raft easily.

2000 Subaru Outback Sedan

This product is advertised for fitting a Subura sedan 2000. However when I received it I had to due massive modifications in order for it to work. I called the help line and the person on the other side was absolutely NO help and I am pretty sure he has never wired trailer lights in his life!!

This wiring harness is indeed a fit for a 2000 Outback factory tow package-equipped models only. To determine if the vehicle is equipped with the tow package, look in the access panel behind the drivers side taillight. There should be a connector present. If the connector is not present, this particular harness will not work.
-- Etrailer Expert Mike L - 08/02/2018

2001 Subaru Forester

Purchased this product along with a bolt on receiver hitch for my subaru forester. The wiring harness plugged right in, super easy install. I was actually surprised, it had correct plugs, operated perfectly, and has lasted with use. It also is easily stowed away, I just put it in the spare wheel compartment. Couldn't have asked for a better product. I plug my four pin trailer light connector in and it works every time.

Chevrolet Colorado

I have ordered 5-6 trailer hitches from etrailer over the past few years. Delivery has always been fast with excellent packaging.
This order was no different. In the past, the hitches installed with very little difficulty.
I this case, I was not able to install before my daughter left for work as a hotshot in Colorado. But I have not doubt that in six months, when she returns, it will install as effortlessly as the ones in the past.
Thanks for your quality of products and very helpful staff.


I have purchased this product before but it went out unexpectedly past the warranty date; so I am forced to purchase again. This time there is a battery fuse compartment included with the unit.

I havent had any problems and I like the new in line fuse holder which protects my vehicle wiring
David H - 11/04/2015

2005 Subaru Outback Wagon

I replaced a dead tail light connector on my 2005 Subaru Outback Wagon. A local car shop did the wiring several years ago, and when getting the boat ready this season, I finally figured out that the tail light connector had died. Wish I had known about this Subaru-specific plug-n-play option when I had the original hitch wiring installed. Insanely easy to install/replace. I just followed the instructions someone posted here to find the connector in the cargo area. I had no idea it existed, and I'll bet the people who installed the hitch/wiring didn't either. Once you have the plug int he cargo area, you can finish in just a few minutes.

I'm going to run the wiring down to my already-existing connector mounted by the hitch receiver and connect there to make everything clean, but you don't need to, and can be up and running in a few minutes.

2003 Subaru Forester

We chose mainly because of the GREAT installation videos they provide, for LOTS of vehicles. This time we just got a trailer electrical hookup, which was easy to attach - we'll definitely go back for more more major items. Service and delivery are great.

Subaru Forester

A snap to installQuick and easy- ONCE you find the wiring harness plug. My Forester had the plug hidden behind a flap directly under the passenger side taillamp, not in front of the spare on the passenger side as shown in the photo.

2005 Subaru Forester

The connector arrived in just a couple of days. Exact replacement of the one that had gotten wet (in the spare tire well). I expect installation to be simple and my trailer lights will be working again.


ordered on saturday and received on tuesday. heavy duty and only took 10 minutes to hook up. This was not the first time I have ordered from etrailer. Have been pleased with product and service on all my orders.


Outstanding!! Fastest shipping I have ever seen! (and inexpensive also)

Saved me hours of work and at least a hundred dollars!

Would recommend for any trailer hitch needs.

Outstanding in every way.

Thank you.


Easy to install. I like the fact that the four pole extension to the trailer can be removed easily.

1996 Subaru Legacy

I ordered a trailer wiring system for my 1996 Subaru and it came very quickly, and plugged right into the receptacle. I was happy with the service and product. I would order from e-trailer again.


Great product at a reasonable price! Would order from this vendor again. Enclosed instructions were great! 5 stars.


EASY Install. I watched a video under installation instructions and completed the task in under 10min.

2006 BMW X3

it was fine except instruction said for my access for the plug in had a 3 x3 door which there wasn`t on my 06 I had to take off inside panel to get it.


Product arrived in record time. Installed it in 20 minutes using the videos on the web site. All email questions were answered in a timely fashion. Very satisfied with the product and the dealer.



Was exactly as advertised and was easily installed especially after watching the video installation guide provided

2007 Subaru Forester

etrailer helped me identify my trailer wiring harness perfectly. Set up took about 20 minutes. My order was handled professionally and shipped quickly--a five star experience!

Show More Reviews

See what our Experts say about this Hopkins Custom Fit Vehicle Wiring

  • Where to Find the Trailer Wiring Connectorfor On a 2009 Subaru Outback
    On the Legacy Outback Wagon the wiring harness is sometimes hard to find. For some reason it gets routed differently and can be in the spare tire well, up along the back near the bottom of the rear seat or under the rear panel nearest the hatch. I spoke to our installation technician and he said that he removes all of the panels and follows the vehicle wiring harness along until he comes across the connector. It is there you just have to search for it. Our instructions are correct for most...
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  • Troubleshooting Hoppy Trailer Harness Part 33855 on a 2001 Subaru Forester
    Use a circuit tester and go to the plug on the vehicle that you connected the harness to. Disconnect the trailer harness. Look at the picture I have linked below. In the picture, the pin on the top left corner should be the left blinker pin. Test this pin on the vehicle connector. Have someone activate the left blinker. If your circuit tester flashes with the blinker, then the Hoppy harness is probably bad. If your circuit tester does not flash, then there is a problem on the vehicle....
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  • Wiring Harness Plug on a 2002 Subaru Outback
    The Subaru Outback connection point is located by removing a 3 inch x 3 inch interior access panel behind the driver side tail lamp housing.
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  • Where Does Hopkins Trailer Wiring Harness Plug Into on a 2001 Subaru Outback
    On your 2001 Subaru Outback there is a 3 inch square access panel located behind the driver's side tail light housing. Remove that panel and look for the mating connector to plug in Hopkins wiring harness # 33855. I have included a picture of what the connector on the vehicle will look like. The video linked is not exactly the same in terms of installation but will give you an idea of what you are looking for.
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  • 7-Way to 4- or 5-Way Adapter for 2013 Honda Ridgeline w/Factory 7-Way and PWC Trailer w/4 or 5-Way
    Yes, there are adapters to go from the 7-Way on your 2013 Honda Ridgeline to a 4- or 5-Way trailer connector on your trailer. A popular adapter for this situation is # 37385. It plugs into the 7-Way on the vehicle and has separate 4 and 5-Way ends on the other side for the trailer. You usually see 5-Way trailer connectors on boat trailers or any trailer that has an electric reverse lockout on a surge break actuating coupler.
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  • Trailer Wiring Connection Point for a 2005 Subaru Outback Wagon LL Bean Edition
    The connection point for trailer wiring on a 2005 Subaru Outback Wagon is usually located behind the paneling on the passenger side, directly below the tail light. I have included a video and the installation details for a similar harness that also fits your vehicle (# 118461). It can also be located on the drivers side, behind the side panel a few feet toward the front of the vehicle. The connector itself is sometimes located behind the wiring harness, so it is difficult to see. You can...
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  • Trailer Lights on 2 Different Trailers Do Not Work When Connected to a 1999 Subaru Forester
    It is possible that there is an in-line fuse somewhere back from the 4-Way end on your 1999 Subaru Forester. You will need to follow the wiring back as far as you can to determine if there is indeed a fuse. If you cannot find one then consult the vehicle owners manual for all of the fuses/relays in the vehicle associated with the wiring harness. Some vehicles have wiring fuses under the hood and inside the in-cab fuse panel. If you have an aftermarket harness like # 33855 then you can...
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  • Trailer Wiring Harness Recommendation for a 2013 Honda Ridgeline
    For a 4-way wiring harness for your 2013 Honda Ridgeline you would want to get a Tow Ready Custom Harness # 118400. I attached an installation video for this kit as well as installation instructions for you to check out. Current pricing is available on the product page.
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  • Location of the Trailer Wiring Connector on a 2002 Subaru Legacy Outback Wagon
    On the 2002 Legacy Outback Wagon the wiring harness is sometimes hard to find. For some reason it gets routed differently and can be in the spare tire well, up along the back near the bottom of the rear seat or under the rear panel nearest the hatch. I spoke to our installation technician and he said that he removes all of the panels and follows the vehicle wiring harness along until he comes across the connector. It is there you just have to search for it. Our instructions are correct...
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  • What is the Correct Trailer Wiring Harness for a 2010 Subaru Outback Wagon
    The correct trailer wiring harness for a 2009 Subaru Outback Wagon is # 118461 or # 33855. For a 2010 model, the correct wiring harness is Tow Ready Custom Fit Vehicle Wiring, # 118467, and if you have this harness then it would be correct for a 2010 model. I have included a link to the installation instructions and a video showing a typical installation.
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  • Will the Hopkins Custom Fit Vehicle Wiring Work on my 2006 Outback Sport
    I spoke with my contact at Hopkins and he informed me that if you have the correct connector as shown in the pictures of the product page of the Hopkins Custom Fit Vehicle Wiring # 33855 then you can use the # 33855 for tail light wiring. The Tow Ready Wiring # 119190KIT would also work for you, but it would require that you splice into the tail light circuitry of your vehicle. For that reason I would recommend that you use a # 33855.
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  • Trailer Wiring Harnesses for a 2005 Subaru Outback Sedan
    The factory connector to plug in a trailer wiring harness should be relatively in the same spot on your 2005 Subaru Outback Sedan as it is in the wagon models. That is to say behind the rear most trim panel in the trunk area on the passenger's side of the vehicle. I have linked a video showing an example installation for you. If you are unable to locate the factory harness or if your Outback is a model that did not receive one you would need to use a hardwire harness such as # 119190KIT
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  • Trailer Wiring Harness Recommendations for a 2001 Subaru Outback Sedan
    For your 2001 Subaru Outback Sedan we have wiring harness # 33855 that plugs into a factory plug at the back of the vehicle. I have included a couple of videos featuring this harness for you. If you are unable to locate the factory plug to plug in the harness then I recommend using ZCI harness # 119250KIT. The ZCI harness does not require cutting and splicing into the vehicle wiring. It has connectors that clamp around the tail light wiring on the vehicle and sense the current running...
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  • Will the DrawTite part # 36284 Fit my 2001 Subaru Outback LL Bean Edition
    Yes! The Draw-Tite Trailer Hitch Receiver part # 36284 is designed to fit all models of the Outbsck including the LL Bean version with the exception of the Outback Sport. It is custom fit and offers a very straight forward installation. It offers a 300 lb. tongue weight rating and a 3500 lb trailer weight rating. Be sure to check your owners manual for your Outback's rating and don't exceed that or the hitches capacity. If you will be towing a trailer use the Tekonsha T-One Vehicle Wiring...
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  • Installing Trailer Connector on 2000 Subaru Outback for Trailer with Surge Brakes
    Either the # 33855 you mentioned or the # 118461 would provide a working 4-pole trailer connector for your Outback. From there, you would need an adapter like # 37185 to convert the 4-pole to a 7-way. The adapter provides a 7-way blade-style connector, as opposed to a 7-way round pin connector. If your trailer uses a 7-way connector with the round pins, you can either use an additional adapter like part # 47595 or remove the round pin connector from the trailer and install the much more...
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  • Wiring, Base Plates, Tow Bar and Accessories Needed to Flat Tow a 1997 Ford Ranger
    To flat tow your 1997 Ford Ranger behind a motor home, you will need a special wiring set up. A regular wiring harness will not work. There are a couple of options for you. First, if you will not be towing the truck very often, I recommend using a magnetic light kit like # RM-2120. If you will be towing the truck frequently, I recommend a diode kit, # RM-154. I have included a link to a video that shows a typical installation of this kit for you. Installation of a magnetic kit is simple...
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Info for this part was:

Employee Mike L
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Mike L
Employee Robert G
Expert Research:
Robert G
Employee Patrick B
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Patrick B
Employee Michael H
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Michael H
Employee Jameson C
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Jameson C
Employee Jeff D
Installed by:
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Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
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