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Tail Light Isolating Diode System with Wiring Harness

Tail Light Isolating Diode System with Wiring Harness

Item # 38955
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Tow Bar Wiring
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Hopkins Universal Tow Bar Wiring - 38955
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Allows motorhome or R.V. to power the lights on the towed vehicle without power feedback. Lowest Prices for the best tow bar wiring from Hopkins. Tail Light Isolating Diode System with Wiring Harness part number 38955 can be ordered online at etrailer.com or call 800-298-8924 for expert service.
  • All Info
  • Reviews (148)
  • Q & A (173)
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  • Why etrailer?

Hopkins Tow Bar Wiring - 38955

  • Diode Kit
  • Splices into Vehicle Wiring
  • Hopkins
  • Tail Light Mount
  • Universal

Allows motorhome or R.V. to power the lights on the towed vehicle without power feedback.


Features:

  • Includes 4-pole flat trailer connector.
  • Max amperage per diode: 3 amps
  • Max voltage: 24 volts
  • Wire lead: 35' long
    • White ground wire measures 42" long.
  • Wire configuration:
    • Brown: Left and right side running lights
    • Green: Right side turn and brake lights
    • Yellow: Left side turn and brake lights
    • White: Ground


31821

Please note - 3 wire system on towed vehicle: If the towing vehicle has a 3 wire system, where the brake signal is sent along a separate wire from the turn signals, then a wiring converter (118158) and 2 additional diodes are needed to retain separate amber turn signals. If you only use this diode kit (38955), then the vehicle brake lights will function as brake and turn lights.




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38955 Tail Light Isolating Diode System with Wiring Harness






Customer Reviews

Tail Light Isolating Diode System with Wiring Harness - 38955

Average Customer Rating:  4.8 out of 5 stars   (148 Customer Reviews)

Allows motorhome or R.V. to power the lights on the towed vehicle without power feedback.

- 38955
by:

A great set that could only be improved on if it had six diodes. 895626



- 38955
by:

Service is top notch. Especially Sarah !!!! Ran into a issue with someone altering OEM on current tow set up and Sarah was able to trouble shoot over the phone and sent me what I needed. Etrailer has had my business and will continue to get it. I’m using the Demco Commander tow bar and base plate on a 2017 GMC 3500. Pulling with a Damon motor home. 845619



- 38955
by:

Works greatly and easy to install 844218



- 38955
by:

Came with everything needed to wire my truck for towing behind my RV. Good quality, fast delivery and good prices....what more could you ask for! 791272



- 38955
by:

everything worked great and couldn't be happier! 782410



- 38955
by:

Did all it was supposed to do. Timely shipping Priced way less than local RV shop 765137



- 38955
by:

This was easy to install and is working perfectly. 745845



- 38955
by:

Product was exactly as advertised, and as I wanted. Delivered as stated. etrailer is a great company to work with. This is the second vehicle I have outfitted, and they have had great videos and directions with their products. 712044



- 38955
by:

Looks good when lites come on 708376


Comments
No issues after one year of use would recommend to anyone
Askconc1 - 09/28/2020

101544

- 38955
by:

I did not install the item myself but it was easily done and works great. 665897



- 38955
by:

Service was great. Follow up on my order was very helpful and appreciated. The parts were received in time to get installed on the new vehicle for our up coming trip. Would recommend etrailer to all my friends. 640431



- 38955
by:

Wired my Jeep for towing behind my motor home this product was great and easy to install. 634303



- 38955
by:

Great product, no problems, works great, and good follow up 617116



- 38955
by:

I wish they would have included a few extra terminals. Those things tend to break or get lost in the process, so a few more would have been nice. Instructions in the package were mostly useless, but there is plenty of documentation on the website listing. 596592



- 38955
by:

Great product! We have towed our Jeep all over the country with no problems with this harness! I highly recommend this product! 592021



- 38955
by:

Haven't installed the product yet- can't understand the instructions & diagram. When Hopkins having their products made in Mexico- it hurts US workers and hurts US consumers also ! I've purchased a product that I can't install, due to the vague instructions & diagram. I would appreciate it , if you would send me something that I can understand. JR 581796


Comments
I see that you are installing this kit on a 2015 Kia Soul. I have a attached a video of an installation of a diode kit on a 2015 Kia Soul. The video is for a part number that includes a coiled cable but it is the same install for the hopkins part # 38955.
-- Heather A - 11/13/2018

45691

- 38955
by:

The installation of these wires were straight forward and easy to complete. After 1 year of use the system is still working perfectly! Highly recommended product to enable towed vehicles turn and brake lights vice separate set of lights. Set up once and no further action required. 568368



- 38955
by:

Quick delivery, great price Already installed and works great! 567244



- 38955
by:

I installed the product on a 2012 Chev Cruze. Very easy to do and only took a couple of hours. Lights work as expected with no surprises. Would recommend to others. 565368



- 38955
by:

Excellent customer service from etraile r! 528277



- 38955
by:

1950 Spartan Royal Mansion. Thank you for your ongoing help and wide array of products!!! 501745



- 38955
by:

Wiring and diodes are high quality. Diodes are marked for ease of installation and the supplied connectors work very well. Installation directions are easy to understand. 492475



- 38955
by:

This is exactly what I need Quick and easy installation Thanks etrailer. 491295



- 38955
by:

Exactly what I needed to hook up my tow lights on my we 2001 jeep grand Cherokee limited. This kit makes it fast and easy. 483052


Comments
Still working great
Tim - 03/09/2019

50344

- 38955
by:

Exactly what I needed. 461664


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Show More Reviews

Ask the Experts about this Hopkins Tow Bar Wiring

  • Tail Light Isolating Diode Kit to Prevent Back-Feeding When Flat Towing
    You can use an isolating diode kit like # 48955 to prevent tail light back-feeding in your flat towing set-up. Each stop and turn circuit (4 in total) will need a diode to allow signals to travel in only one direction, without back-feeding to the RV.
    view full answer...
  • Does a Vehicle on a Tow Dolly Need Tow Bar Wiring
    Since your tow dolly has taillights on it already you shouldn't need to also have the taillights of the vehicle you are towing activate as well. You should be good to go for towing your vehicle behind your RV with the tow dolly as long as it's taillights are functioning.
    view full answer...
  • Brake Light Relay to Prevent Motorhome Turn Signals Being Overridden By Brake Lamp on Towed Vehicle
    You'll need to install a Roadmaster Brake Light Relay, part # RM-88400. The purpose of a brake light relay kit is to prevent your towed car's brake signal from overriding the turn signal that comes from your RV. When your towed vehicle is properly wired and connected to your RV, its indicator lights will illuminate as you engage the turn signals in your RV. However, if you have only a four-diode system in place, the turn signal will be overridden by your towed car's brake signal as soon...
    view full answer...
  • Necessary Equipment for Towing 1999 Jeep Grand Cherokee Behind Motorhome
    According to my research, if your Grand Cherokee has a manual transfer case with a Neutral position, it can be flat towed, unless it has the Quadra Trac I 4 wheel drive system. There is a specific procedure that must be followed, which is outlined in your owner's manual. From what I read online, the Jeep WJ (Grand Cherokee 1999-2004 model years) is a popular vehicle to flat tow. The WJ is lighter than later models, which makes it good for flat towing. In order to flat tow your Grand...
    view full answer...
  • Tow Bar Wiring to Flat Tow a 1996 Geo Tracker Behind a Motor Home
    You can use a diode kit like # 38955 on your 1996 Geo Tracker but there are several things to consider. First, it looks like your Tracker has turn signals that are separate from the brake and running lights. If this is so then by using a 4 diode kit, all the functions will use the brake/running light bulb and the vehicle turn signals will not be used at all. If the towing vehicle (RV) has separate bulbs as well and no trailer connector, you would either need to use a tail light converter,...
    view full answer...
  • Can a Tail Light Isolating Diode System Be Used on a Chevy Colorado with Separate Brake Light
    Yes, you can use the 4-Diode System, part # 38955, to wire your Colorado. As you pointed out, the turn and brake signals will not longer be on separate bulbs. The diodes should be sealed enough that they will hold up mounted near the tail lights. I would not put them in direct exposure to rain or road water. I would mount them behind the tail light housings using the light fixture seal to block out most of the rain water. I would also use a dab of dieletric grease, part # 11755, at each...
    view full answer...
  • Wiring a 1999 Jeep Grand Cherokee with Diodes to Flat Tow behind a Motor Home
    We actually have some helpful diagrams on the product page for the Tail Light Isolating Diode System, # 38955, as well as some videos and an FAQ article that I have linked for you. All of these items should be a big help. When checking the wires on the vehicle to determine function, you will need a circuit tester like # 40376. You will probe the wires behind each tail light to find the turn signal, running light, and brake light wires. You will then wire them into the diodes according...
    view full answer...
  • Will Supplemental Braking System and Tow Bar Wiring from RV Overload Brake Lights on Toyota Tacoma
    Both a brake light signal from the motor home and the brake signal from the vehicle are 12 volt systems. If both are supplying power at the same time to the same circuit it would not overload it because it would not double up the power to 24 volts. You may need a brake light relay # RM-88400 to keep the Tacoma brake signal from overriding the turn signal sent by your RV. The relay is needed on towed cars with combined lighting if you are using a supplemental braking system. Combined...
    view full answer...
  • How to Wire a 2007 Jeep Wrangler so All Running Lights Work Front and Back When Used as Toad
    If you want to run the lights at the front of your toad you will need to install a diode at each running power wire going into the light bulb socket. You would need extra diodes, # 48955, and you would need to splice in extra wiring, # DW02360-1. Wiring the front running lights will be similar the wiring the rear running lights, see attached photo. You will need to make sure that your towing vehicles trailer wiring is capable of handling the extra amperage required by adding the...
    view full answer...
  • Using Hopkins Tail Light Isolation Diode Kit, Part # 38955, In 2013 Honda Fit Being Flat-Towed by RV
    The Hopkins Tail Light Isolation Diode Kit, Part # 38955, prevents braking signals generated in your towed Honda Fit from feeding back into your RV lighting system when you are using a supplementary braking system such as the Ready Brake. Please refer to the linked installation video showing how the diode kit installs in a 2010 Honda Fit. You indicate that your RV has a combined lighting system - brake and turn lights carried on the same wire. You may be able to use just this diode kit...
    view full answer...
  • Wiring Colors Explained for Tail Light Isolating Diode System # 38955
    You are correct in everything you mentioned. The part # 48955 is just the diodes of the part # 38955. The two brown wires are running lights to either side, yellow is left turn/stop, and green is right turn stop. White is ground.
    view full answer...
  • Which Tow Bar Wiring Diode Kit is Used to Flat Tow a 2003 Chevy Tracker Behind a Motor Home
    The diode kit recommended for your 2003 Chevy Tracker is actually the 6-diode kit # 154-792-118158. Those 2 additional diodes will allow the turn signals and brake lights to be separate on the Tracker when it is being towed. When using a 4-diode kit such as # 38955 the red brake lights will function as both brake lights and turn signals which is perfectly legal if that is what you are worried about. Since you already have a 4-diode kit at the very least you will just need 2 more...
    view full answer...
  • Wiring Needed for Towing a 2007 Kia Rio with a 2008 Freedom Express Class C RV
    Your Kia requires a taillight converter, so you will need the Tail Light Isolating Diode System, part # 38955 and the Vehicle to Vehicle Taillight Converter, part # 118158 along with two extra diodes, which will require purchasing the Tail Light Isolating Diodes Qty 4, item # 48955, or the Roadmaster Hy-Power Diodes Qty 2, item # RM-792. If you do not mind the brake lights blinking when the turn signals are activated then you can just use the Tail Light Isolating Diode System, part #...
    view full answer...
  • Wiring a RV to Tow a 1998 Saturn SL2
    To wire your RV to tow your 1998 Saturn SL2 you will need part 38955. This kit will use the Saturn brake lights for both the brake lights and turn signals. If your SL2 has amber turn signals, you will also need part 118158, and two extra diodes, item # 48955, if you would like the amber turn signals to function.
    view full answer...
  • Does my Tow Bar Wiring Harness Require the use of Hy-Power Diodes
    Wherever you use the RV to signal the vehicle's factory lights, diodes will be needed to stop the backflow of electricity. If you are using a set of external lights like part # TL21RK then the diodes will not be needed but since you have the wiring harness attached to your factory lights then you will want to use a set of diodes like part # RM-794. I have attached a diode installation help article for you to take a look at as well.
    view full answer...
  • Wiring or Lighting Recommendation For Flat Towing a 2011 Chevy HHR Behind a Motor Home
    There are actually a couple of different ways you can add wiring or lights to your 2011 Chevy HHR so it can be flat towed behind a motor home. I have included a link to an FAQ article that explains the different options. If you plan on towing the HHR often, it would be beneficial to install diodes using Roadmaster Universal Hy-Power Diode Wiring Kit, # RM-154. I have included a link to a video showing a typical installation. If you do not plan on towing it often, I recommend going...
    view full answer...
  • Pollak 6-Pole Trailer Wiring Socket # PK12720 Recommendation for Flat Towing a 2011 Honda Fit
    I would recommend you remove the 4-wire flat plug and replace it with a Pollak 6-Pole, Round Pin, Plastic Trailer Wiring Socket, part # PK12720, like you mentioned. This way you would not have to use an adapter which would give you a cleaner install and give you one less component that could potentially fail on you. I attached an FAQ article on tow bar wiring below for you to check out also.
    view full answer...
  • Wiring Lights for a 2001 Toyota Tacoma Being Towed by a RV
    Of the various available solutions available, the easiest method would be to use a magnetic towing light like part # C-ATL20A. This is a good option for occasional use. A more permanent wiring solution would be the Roadmaster Bulb and Socket Kit, part # RM-155. This kit uses bulbs that would install through 1 inch holes drilled into the back of the tail light assemblies. This solution allows the tow lighting wiring to remain completely independent of the wiring of the Tacoma. The install...
    view full answer...
  • Does Tail Light Isolating Diode System Work With LED Lights
    Yes, the Tail Light Isolating Diode System with Wiring Harness # 38955 will work with LED lights. I have added links to a couple video reviews of this system for you to check out as well.
    view full answer...
  • Will Magnetic Tow Lights Work if Plugged into the 4-Way Connector of the Towed Vehicle
    You will need to plug the magnetic lights into the RV 4-Way since the 2017 Jeep Wrangler 4-Way will not have power and the lighting system you have will not provide power to the Wrangler's 4-Way. Plug them into the RV and it will solve the problem.
    view full answer...
  • Wiring a 2000 Nissan Frontier with Diodes to Flat Tow
    Since your 2000 Nissan Frontier has separate turn signals and brake lights there are a couple of options. You could use just 4 diodes and the lights on the truck will function as a combined system. You will also need a brake light relay, # RM-88400, for use with a supplemental braking system if you want to just use 4 diodes. If you want to retain the separate brake and turn signals on the vehicle you would need to use 6 diodes if the towing vehicle also has a separate system. Basically...
    view full answer...
  • Is it Safe to Use Tail Light Isolation Diodes on a 2005 Jeep Wrangler TJ for Flat Towing
    Yes, it is safe to use diodes on your Jeep Wrangler. Diode Kits, like the Hopkins Tail Light Isolating Diode System, item # 38955, are designed to stop any power feed back onto the vehicles electrical system. If it concerns you, and drilling a hole in the tail light housing is not an issue, you can definitely use a bulb kit on your TJ. Blue Ox recommends the Blue Ox Tail Light Wiring Kit, item # BX8869, along with the Blue Ox 4-Wire, Coiled Electrical Cord and plugs, item # BX8861. I...
    view full answer...
  • Are There Custom Fit, Plug-In Tail Light Isolating Diode Systems?
    Flat towing a vehicle is not something that as may people do as say using that same vehicle for towing a small utility trailer. None of the towing parts manufacturers, at least to my knowledge, have started building custom fit diode kits because the demand would not be there to offset the design and engineering costs. The T-One harness you installed, cannot be used in reverse. Trying to send power the other way at best would simply not work, at worst it could cause damage. There is...
    view full answer...
  • Brake Light Relay Recommendation for Vehicle Where Braking System Pushes Brake Pedal
    We have just what you need for you situation. Roadmaster makes a brake light relay part # RM-88400 which allows your supplemental braking system to apply the brakes without overriding the tow bar turn signals if the blinkers were on. We've also installed it on a similar Jeep Wrangler JK which I attached an install video for to this page.
    view full answer...
  • Tail Light Isolating Diode System # 38955 Install on 2011 Ford Fiesta
    If you go to the product description page for the Hopkins Tail Light Isolating Diode System, part # 38955 and scroll down to the bottom of the page (use the provided link) you will see 4 install diagrams. The wiring method used will depend on the way the tail light circuits on your RV are wired. The lights can be wired in one of two different ways. If your RV uses what we call a combined system, the brake light and turn signals are combined into a single circuit, using a singe bulb on...
    view full answer...
  • Will Hopkins Tail Light Isolating Diode System # 38955 Work on 1998 Toyota Tacoma
    You will be fine using the Hopkins Tail Light Isolating Diode System # 38955 on 1998 Toyota Tacoma. Although this item has not been formally tested on your particular model year truck it will operate properly in your application on a 1998 Tacoma.
    view full answer...
  • Where Should Diodes Be Placed When Installing Tow Bar Wiring On 2003 Chevrolet Tracker
    When installing the tow bar wiring like part # 38955 on your 2003 Chevrolet Tracker, you want to install the diodes as close to the tail lights on your Tracker as you can. I have attached a link to an installation video for this wire harness on an Equinox. The vehicle may be different but you can check out the video at about the 2:20 mark and it shows how they are installing the diodes with the wiring. When installing the wiring on your Tracker you may need to use a circuit tester like...
    view full answer...
  • Can a 4-Diode Tow Bar Wiring Kit be Used on a 2016 Buick Enclave
    Yes, you can use a 4-diode tow bar wiring kit such as # 38955 on your 2016 Buick Enclave. It also appears that fuses have to be pulled to flat tow your Enclave. Consult the vehicle owner's manual to confirm. To make this process as easy as flipping a switch I recommend fuse bypasses # RM-76517 and # RM76514.
    view full answer...
  • What is the Maximum Amperage Rating for Hopkins Tail Light Isolating Diode System # 38955
    The Hopkins Tail Light Isolating Diode System # 38955 includes 4 diodes. Each of the diodes carries a 3-ampere current rating; I confirmed this with my technical contact at Hopkins. In practice this will be plenty of current capacity for the single lighting circuit connected to each diode. I have linked for your reference an installation video for this product showing use in a Ford vehicle.
    view full answer...
  • Can the Hopkins Isolating Diode System Be Used on a 2011 Buick Enclave without Throwing any Codes
    Yes, you can use this Tail Light Isolating Diode System # 38955 on your 2011 Buick Enclave with out it affecting the on-board diagnostics of your vehicle. Check out the video I attached that shows this product being installed onto a very similar Buick Enclave as yours.
    view full answer...

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Info for this part was:

Test Fit:
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Ryan G
Expert Research:
Mike L
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Jameson C
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Adam R
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Video Edited:
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Installed by:
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