Reese Trailer Connector Adapter w/ LED Circuit Tester and Dust Cover - 7-Pole to 4-Pole or 5-Pole

Reese Trailer Connector Adapter w/ LED Circuit Tester and Dust Cover - 7-Pole to 4-Pole or 5-Pole

Item # 78118

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Wiring 78118 - 4 Flat,5 Flat - Reese
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  • Wiring Adapters
  • Multi-Function Adapter
  • 4 Flat
  • 5 Flat
  • 7 Blade
  • Plug Only
  • Reese
This adapter lets you quickly convert your 7-way connector for use with a 4-way or 5-way flat trailer-end plug. It includes a circuit tester with red LEDs and a built-in dust cover that protects the terminals when you aren't towing. Lowest Prices for the best wiring from Reese. Reese Trailer Connector Adapter w/ LED Circuit Tester and Dust Cover - 7-Pole to 4-Pole or 5-Pole part number 78118 can be ordered online at etrailer.com or call 800-298-8924 for expert service.


  • All Info
  • Reviews (22)
  • Q & A (11)
  • Videos (2)
  • Photos
  • Why etrailer?

Reese Wiring - 78118

This adapter lets you quickly convert your 7-way connector for use with a 4-way or 5-way flat trailer-end plug. It includes a circuit tester with red LEDs and a built-in dust cover that protects the terminals when you aren't towing.


Features:

  • Easy-to-use, plastic adapter converts your vehicle's 7-blade, RV-style, vehicle-end connector for use with a 4-wire or 5-wire flat, trailer-end connector
  • Circuit tester with highly visible, red LEDs
    • Lets you check the connectivity of your electrical circuits at a glance
  • Built-in cover protects terminals from dust and grime when you're not towing a trailer
    • If you use dielectric grease, the cover keeps the plug clean for storage
  • 1-Year limited warranty


78118 Reese Trailer Connector Adapter w/ LED Circuit Tester and Dust Cover - 7-Blade to 4-Pole or 5-Pole






California residents: click here


Video of Reese Trailer Connector Adapter w/ LED Circuit Tester and Dust Cover - 7-Pole to 4-Pole or 5-Pole


Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.




Video Transcript for Reese Wiring - Wiring Adapters - 78118 Review

Today we're going to review part number 78118. This is a Reese Trailer Connector Adapter with the LED circuit tester and the dust cover. This will convert the 7 way to a 4 and 5 way. This easy to use plastic adapter will convert you vehicle's 7 way RV style vehicle end connector for use with a 4 wire or a 5 wire flat trailer end connector. It does have the . it's hard to see here but if I show you in between there's a dust cover right up here. This built in cover will help protect the terminals from dust and grime when you're not towing a trailer.

It can cover either the 5 way or you can also even put it on the 4 way, just like that. Right in between, you see the bottom is your 4 way, the top is your 5 way, well right in between there's three red LED lights. The first one is marked with a T, which means the taillight circuit. The next one's marked with the L, which means the left side lights. The other one is an R for right side lights. Once you plug it in those lights will tell you if all of them are working correctly, or if none of them are, which one is not working.

It let's you check the connectivity of your electrical circuits at a quick glance. This side is what plugs in to your 7 way. That should do it for the review of part number 78118 the Reese Trailer Connector Adapter with the LED circuit tester and the dust cover. .


Customer Reviews

Reese Trailer Connector Adapter w/ LED Circuit Tester and Dust Cover - 7-Pole to 4-Pole or 5-Pole - 78118

Average Customer Rating:  4.8 out of 5 stars   (22 Customer Reviews)

This adapter lets you quickly convert your 7-way connector for use with a 4-way or 5-way flat trailer-end plug. It includes a circuit tester with red LEDs and a built-in dust cover that protects the terminals when you aren't towing.

- 78118
by:

Item worked as stated fit good and stayed in place. shipping is fast and easy, item came a day early. Etrailer has great pricing an a great selection. 223273


Comments

Product works as it did on day 1. Holds up in all types of weather. Hats off to Etrailer for a product that works as advertised

Frank D - 08/31/2016

20681

- 78118
by:

Works great, good value, looks like it will hold up well 155885


Comments

Working as it should

Mike M - 10/15/2015

15537

- 78118
by:

Seems well made. Needed for my 2015 Chevy Surburban since it only has 7 way plug and I needed 4 way also. The test lights should come in handy in the future. 405049



- 78118
by:

My first experience with etrailer. It was a pleasure. Great products at reasonable prices, with fast shipping. This adapter performs as advertised. It is a very convenient way to test your vehicles wiring, without having your trailer hooked up. If I were to be really picky, I would have liked it to have a tighter fit in the vehicle's socket. I'm sure it will be fine though. I would definitely recommend etrailer! 119956



- 78118
by:

awesome 474235



- 78118
by:

nice product good quality 107378


Comments

The product work as advertised and the delivery was first rate and timely!

albert c - 11/14/2014

7671

- 78118
by:

Works as advertised. Etrailer service and prices excellent. 42522



- 78118
by:

Easy to install. Prompt delivery. Great customer support and service. 672027



- 78118
by:

Product works as advertised. LED lights work great to check for faults in trailer or vehicle circuits. 650224



- 78118
by:

Perfect, just what I needed, fast deliv ery. 649398



- 78118
by:

Works great for the basic checking of turn, brake and running lights. Overall fit and design is great. 611277



- 78118
by:

Fits perfectly and seems to work although I haven’t actually hooked the trailer wiring to it yet. But the leds light as expected. 599580



- 78118
by:

Just what I needed for the two trailers I have, one with 4 pins and one with 5. Nice dust cover for the one not in use as well. 443272



- 78118
by:

Well built outstanding adapter. Indicator lights make quick check of lighting systems. 434452



- 78118
by:

Great products and pricing 389193



- 78118
by:

Great adapter with the tattle tale LEDs to indicate what lights are energized for trouble shooting circuit problems. 302209



- 78118
by:

Good choice! 155350



- 78118
by:

Received in a timely manner and seems to be working as advertised. 132259



- 78118
by:

Looking forward to using it. Etrailer is the only way to go! 120586



- 78118
by:

Great product! 110347



- 78118
by:

I find this product very useful when determining where my trailer light problems are. Having the LEDs built into the plug is a great idea. 84685



- 78118
by:

Does what it is advertised 46489


22
22

Ask the Experts about this Reese Wiring
Do you have a question about this Wiring?


  • Only Left Trailer Light Shows Power with 1999 Chevy Tahoe
  • There are several things you can check to determine why a trailer wiring circuit is not working. First, you will want to test the vehicle side trailer connector using a circuit tester such as # 40376. Have someone sit in the vehicle and go through the light functions while testing. If everything works on the vehicle you can move on. If a circuit is not working on the vehicle then make sure the trailer connector is clean and free of corrosion inside and out and inspect the wiring, fuses,...
    view full answer...

  • Will Reese 78118 7-Way to 5-Way Adapter Work Well Towing Boat Trailer with 5-Way
  • Yes, the Reese Trailer Connector Adapter w/ LED Circuit Tester and Dust Cover # 78118 that you referenced would be exactly what you'd want. This will plug into the 7-way of your Tundra and give you a functional 5-way to use with your trailer that has surge brakes. In case you were curious the 5th pin of a 5-way carries the reverse light circuit which is what activates the reverse lock out solenoid on your trailer that will allow it to back up without applying the brakes.
    view full answer...

  • Availability of 7-Way to 4-Way Adapter that Fits 2003 Toyota 4Runner
  • Yes, the 7-way adapter part # 37385 and # 78118 will both fit the factory 7-way you have on your 2003 Toyota 4Runner. They will simply plug into the 7-way on your vehicle and be ready to go.
    view full answer...

  • Comparing Reese and Hopkins 7-Way to 5-Way Adapters
  • I'd recommend the Reese # 78118 7-way to 5-way adapter over the Hopkins part # HM47675 that you also mentioned because the Reese comes with a circuit tester which for most people would be more useful than what the Hopkins has instead which is a 12 volt power circuit. There are quite a bit more situations where people are in need of a circuit tester than a 12 volt power supply so I believe it would be much more useful to you. I attached a review video for the Reese for you to check out...
    view full answer...

  • Running Lights Not Working With Reese Trailer Connector Adapter w/ LED Circuit Tester # 78118
  • Since you mention that the LED light on the Reese Trailer Connector Adapter, # 78118, isn't illuminating for the tail lights, it sounds like the issue is with the truck but this could be something as simple as dirt or corrosion in the 2013 Ford F-150's 7-way connector. If the pin looks clean then the issue may very likely be a blown fuse or faulty relay. If everything checks out to be fine and the running lights on your trailer still aren't functioning properly, please feel free to...
    view full answer...

  • Adapting a Semi Truck 7-Way to RV Style 7-Way to Use Wireless Light Kit to Flat Tow a Van
  • There isn't an adapter to go from a semi truck 7-Way to an RV style 7-Way but you could hardwire in a separate RV style 7-Way on the semi truck. You can use a circuit tester such as # 40376 to test the wires at the back of the semi 7-Way. It should have separate circuits for each turn signal and brake lights. If so then you will need to combine the separate circuits using a converter # RM-732 because an RV style 7-Way has combined turn signal/brake light circuits. On the converter...
    view full answer...

  • How do the LED Lights Work on Reese Trailer Connector Adapter w/ LED Circuit Tester 78118
  • The LED lights on the Reese trailer connector adapter # 78118 will tell you if the corresponding circuit is working. The light on the far left will tell you if the running light circuit has power. There is a T next to it for Tail Lights. In the middle is the light for the left turn/brake light circuit. And the far right is for right turn/brake lights. If you turn on the vehicle head lights then the T light will be on. If you step on the brakes, the other two will light up. Or if you...
    view full answer...

  • Looking for Adapter to Convert 7-Way on Vehicle to 5-Pole Connector on Trailer
  • I'm assuming you're needing the adapter for a boat trailer that has a surge or hydraulic coupler. The 'brake' wire doesn't carry power to the trailer brakes, it merely 'locks out' the hydraulic coupler when the vehicle transmission is shifted into reverse so the trailer can be backed up without the trailer brakes coming on. If this is the case, I'd recommend the Reese # 78118 adapter, that's compatible with either 4-pole or 5-pole trailer connectors.
    view full answer...

  • Troubleshooting 2 Lights Blinking on the Reese Trailer Connector Adapter # 78118
  • The only reason two of the lights would be blinking under normal circumstances would be if the circuits that were blinking where the left and right stop/turn signals and it was because you had the emergency flashers of your vehicle on. Otherwise that indicates you have some kind of short and I would recommend you check the back of your vehicle connector for corrosion or any other obvious problem such as exposed wire and fix as necessary.
    view full answer...

  • Adapter for 4-Flat on Truck and 7-Way on Trailer
  • We do have a solution for you, though the Reese Trailer Connector Adapter # 78118 will not work for you. Instead I recommend the Hopkins Endurance Quick-Install Trailer Connector Adapter # HM47200 which will plug into your truck's 4-way and allow you to connect your trailer's 7-way.
    view full answer...

  • Can the 4-Way and 5-Way of the Reese Trailer Connector Adapter # 78118 be Used at Same Time
  • Yes, both the 5-way and the 4-ways of the Reese Trailer Connector Adapter # 78118 could be used at the same time. Since a 4-way can plug into the 5-way you could use both of your 4-way connectors. You would need to also be sure not to overdraw the taillight circuits of the vehicle's wiring. Powering two sets of trailer lights may be too much for the adapter.
    view full answer...


Do you have a question about this Wiring?




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Info for this part was:

Photos by:
Theodore B
Written by:
Tyler C
Expert Research:
Michael H
Expert Research:
Jameson C
Video Edited:
Jacob T
Updated by:
Adele M
Updated by:
Laura H
Photos by:
Sam P
Installed by:
Randy B
Updated by:
Alexander C
Video by:
Zach D

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