4-Way Adapter that Allows 12 Volt Charge Circuit for Compressor

Updated 06/23/2025 | Published 06/06/2025

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Question:

I want to utilize this 4 to 5 adapter plug to use the blue wire to my 12 v power to power my tiny air compressor 15 amp . I have the Tekonsha 118701 wiring set up. . Can I just splice it into my black power wire off that Tekonsha? Its fused at the battery with a 15 amp fuse.

asked by: Dave

Expert Reply:

Hey Dave, I can appreciate the clever idea you have of using the part # 47515 drawing power from the power wire of the Tekonsha part # 118701 but that wouldn't work. The 16 gauge wire of the adapter can't handle 15 amps, and the power circuit from your 4-way can't handle the additional power draw.

Best option is to use the # ETBC7L which will convert the 4-way to a 7-way and comes with the wiring needed to activate the 12 volt accessory circuit. You'll need to have a 7-way installed on your trailer as well though like with the part # H20042 as well.

Is the compressor on your trailer?

expert reply by: Jameson C

David

6/10/2025

Well ….. lol…… I’m going to do it and damn the consequences!!! I actually did the 7 pole on my other Prius and what a quagmire of nonsense…looks like I’m a big rig . I have never installed the 7 pole on the trailer. You did say the 16 g and the converter box on the tekonsha 118701 won’t handle the load … I respect that but…. I’m going to split the hot wire between the battery and box and run a hot lead to the 4 to 5 adapter… it’ll be fused at 15 amps ( if not I will). I can’t imagine the Hotwire on the tekonsha 118701 is 16g that’s wimpy… anyway I’m not going to install the 7 pole as I did all that and still bypassed the ding dong Hotwire with a straight wire that was like 12g.. I appreciate your advice and maybe run a meatier Hotwire and do some kind of silly 4 to 5 connection

Jameson C.

6/10/2025

@David Understandable! Let us know how it works.

David V.

6/12/2025

So I received the Hopkins 118701 4 flat with PNP connectors for the Prius.. . The power wire is 12 gauge. For my trailer I need a 5 to 4 flat to run my 15 amp max air compressor. Unfortunately the 5 to 4 is 16 gauge.. this is usually use to run reverse lights or dare I say electric brakes??? In any event I should use something meatier than a 16 gauge wire on the hot side of the 5 to 4 flat . I’d like to be safe although the 16 g at less than 5 ft of length is rated for 15 amps . Look I’m trying to be safe and I’d really like to find a 5 to 4 flat adapter with 12 gauge wire.

Jameson C.

6/12/2025

@DavidV It might be hard to find a 4 to 5-way with that gauge of wire as this adapter is normally use for reverse lockout solenoids that don't draw that much amperage.

David V.

6/12/2025

@JamesonC I appreciate your response! From practical experience I used this same method on my previous Prius project and have around 10k miles utilizing this set up with no issue other than my occasional loose wire. I’m reading the amp ratings and thinking that I’ll be ok. I’d prefer 12 g but feel for the few short (5) feet and the same 15 amp fuse I feel that it should work as well as the other. . I’ll follow up but feel that even with the 16g gauge on the 5 to 4 adapter will handle the 15 amp of the 118701 tekonsha PNP Prius wiring which has the 12 g power wire.