ARB Compressors and AUX Switches

[2Wheel-Lee]

Like 2Wheel-Lee said, and I'll add that you don't need the air tank to run lockers either (just the manifold and solenoid kit). It's really only for that instant boost that's needed for air tools or powering an air horn.

If you're only running ARB lockers, I'd probably prefer not to run a tank, just in case there is a very slight leak in the system. Without the tank, the compressor would almost instantly fire the lockers, in the event the tank isn't pressurized. Although on the other hand, if all is sealed, and your tank is pressurized, you'd almost never have to run the compressor during a day of wheeling turning lockers on and off. My Samurai has ARB lockers and no tank, and I love that I can pressurize the locker solenoids almost instantly.

I only installed a tank in my JL for using an air hose to blow dust out of the interior.

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[DrJoeSchmoe]

If you're only running ARB lockers, I'd probably prefer not to run a tank, just in case there is a very slight leak in the system. Without the tank, the compressor would almost instantly fire the lockers, in the event the tank isn't pressurized. Although on the other hand, if all is sealed, and your tank is pressurized, you'd almost never have to run the compressor during a day of wheeling turning lockers on and off. My Samurai has ARB lockers and no tank, and I love that I can pressurize the locker solenoids almost instantly.

I only installed a tank in my JL for using an air hose to blow dust out of the interior.

The tank would continuously be pressurized by the compressor unless it was turned off. I have a very small leak in my system, and the air compressor kicks on every hour or so to top it off. I guess it all depends on your needs. The tank is simply reserved air pressure, ready when you need a prolonged boost. You can still blow dust out with the power of the compressor and no tank.

Where did you mount the air tank?

 

[MCJA]

You can't connect them directly to any of the Aux switches - as you said, they draw too much amperage. They come with their own 40 amp fuses (1 for each compressor), and you can connect the control wire directly to your OEM Auxiliary switches. No need to install your own relays - the ARB dual compressor kit comes with it already installed.

I did a write-up on my dual ARB compressors and 4-tire system here.

A few pictures of my installation:

 

[RockyMtnHigh]

FYI: the power wires on the twin arb are 10awg. Others have done the aux thing. Run the power and ground wires to the battery and the purple from the arb to your aux hot.

But what about the small black wire bundled with the purple? Everyone says purple to Aux, which I get, but I haven't found anything on that black wire

 

[MCJA]

But what about the small black wire bundled with the purple? Everyone says purple to Aux, which I get, but I haven't found anything on that black wire

The black wire on the wiring harness isn't needed if you're not using ARB's switch kit. (The switches are lit, so they need a ground.) The black wire is a pass-through ground for the ARB switches themselves. In other words, rather than having to connect the ARB switches to a ground stud separately, ARB made it super easy - you just plug their switch wiring harness into the compressor wiring harness, and the switches use the compressor's common ground wire.

The instructions for the ARB compressor come with a wiring diagram. You can "chase" the ground wires. If you do, you'll find that the black wire isn't needed.

Hope that helps!

 

[SilverSurfer]

The black wire on the wiring harness isn't needed if you're not using ARB's switch kit. (The switches are lit, so they need a ground.) The black wire is a pass-through ground for the ARB switches themselves. In other words, rather than having to connect the ARB switches to a ground stud separately, ARB made it super easy - you just plug their switch wiring harness into the compressor wiring harness, and the switches use the compressor's common ground wire.

The instructions for the ARB compressor come with a wiring diagram. You can "chase" the ground wires. If you do, you'll find that the black wire isn't needed.

Hope that helps!

Thank you. I was struggling to figure out what to do with the black wire

I was going to just earth it but as mentioned you only need to connect the purple wire to the Aux power wire.

 

[donmontalvo]

Thank you. I was struggling to figure out what to do with the black wire

I was going to just earth it but as mentioned you only need to connect the purple wire to the Aux power wire.

I'm running an ARB Dual Compressor under the passenger seat in my 2021 JLUR. I wasn't sure what the thin black ground wire was for so I connected it to the main ground wire. I'm using ARB's under seat mount kit, which comes with a switch.

The blue light on the switch is always on, whether I have the switch toggled on or off. I wonder if I should cut the small black ground so the blue switch light is off unless the switch is toggled on?

FWIW, I ran the two black 10 gauge/AWG wires to the battery ground ("-"), and I ran the two 10 gauge/AWG red wires to the battery positive ("+"). Mostly because that's what ARB advises, but even if they didn't, the AUX switches weren't designed for that much power.

EDIT: I'm running a MORRflate hose solution, so I can air up/down all four tires at the same time. Since the ARB under seat coupler is by the door, I run a 7.5' extension (choose ARB from the menu) so the gauge and all hoses come through the two front windows.

 

[dragoneggs]

I installed my ARB twin under the pax seat and ran directly to the battery. I decided to go with the Epic Kraken mounting system (which I absolutely love!) that has a dedicated switch at the pax seat where you plug in for air. No need to use up an AUX switch which I covet for other electrical needs.

https://epic-4wd.com/en-us/collecti...c-kraken-tire-inflation-system-for-jeep-jl-jt

Not cheap but a very clean install with air access at both doors. The wiring fished through pax floor drain plug, through inside of frame rail up to battery behind the inner fender.

 

[J0E]

Like 2Wheel-Lee said, and I'll add that you don't need the air tank to run lockers either (just the manifold and solenoid kit). It's really only for that instant boost that's needed for air tools or powering an air horn.

Or reseating a bead.

 

[Altitude2020]

Great read and excellent video. I want to 8nstall a single ARB compressor in the engine bay with a bracket I found. I have Mopar switches I want to install the compressor on Aux 2. The compressor is for airing up air bags and topping up tires. Nothing major. I need the space in my trunk area for a wheel chair so I have to organize things. I am writting this to follow this thread and maybe get a response.

 

[Vanburi]

You can trigger a relay for the compressor with an aux switch. An aux switch alone will not handle the current draw of the ARB compressor.

 

[Altitude2020]

You can trigger a relay for the compressor with an aux switch. An aux switch alone will not handle the current draw of the ARB compressor.

I'm looking at the single ARB
There are video on YouTube that have it connected to the aux switch with no issues. There is no such thing as a 50 amp switch. Now if you want to ait up 4 tires at once, probably not. If you are airing up air bags and filling the od tire no issue.

 

[MCJA]

It's true that Aux 1 or 2 have the current capacity to handle a single compressor. That said, I would still recommend using a relay even for a single compressor, simply to prevent inductive load damage from the compressor to your electrical system.

That's the TL;DR summary. Here's some extra nerdery if you're interested...

Issue 1:

A compressor is an inductive load - that means it uses electrical current to induce a magnetic field. That field interacts with magnets to create mechanical work. When an electric motor is turned off that magnetic field collapses, which generates current, which flows backwards in the circuit. It's called electro-magnetic fly-back.

Depending on what kind of control components you're using, that fly-back can be damaging to the components themselves or to the power supply itself. There are ways to build in circuit protection to manage the fly-back and prevent damage.

Issue 2:

The factory Aux switches appear to "soft" switches - meaning they're not directly controlling current flow. Rather, they're sending a signal to the ECM which in turn is controlling current flow. In other words, they appear to be computer buttons, not actual "hard" switches.

Issue 1 + Issue 2:

I would hope that the FCA (now Stellantis) engineers had the foresight to expect Jeep owners to use those switches for all manners of electrical loads, including inductive loads. So I would hope that they included circuit protection for the controls. Hope. But without being certain of what kind of circuit protection exists for those switches and / or the ECM, I would still use a relay to control the compressor. That way, your fly-back current isn't traversing any of the soft components - just a relay and a fuse.

It may very well be overkill. And if enough people have already connected directly to the Aux switch outputs, then that's probably plenty of evidence to support that Jeep did it right.

 

[Chugiakguy]

The blue light on the switch is always on, whether I have the switch toggled on or off. I wonder if I should cut the small black ground so the blue switch light is off unless the switch is toggled on?

I'll be installing an ARB dual compressor under the passenger seat, and using those same ARB rocker switches. But I'd prefer to avoid any extra parasitic draw on the battery by having them lit up all the time, even when the Jeep is not running.

So can anyone tell me if those ARB rocker switches are literally lit ALL the time? Or only when the Jeep is running? If only when the Jeep is running, I am fine with that, but if they stay lit at all times, then no.

 

[Altitude2020]

It's true that Aux 1 or 2 have the current capacity to handle a single compressor. That said, I would still recommend using a relay even for a single compressor, simply to prevent inductive load damage from the compressor to your electrical system.

That's the TL;DR summary. Here's some extra nerdery if you're interested...

Issue 1:

A compressor is an inductive load - that means it uses electrical current to induce a magnetic field. That field interacts with magnets to create mechanical work. When an electric motor is turned off that magnetic field collapses, which generates current, which flows backwards in the circuit. It's called electro-magnetic fly-back.

Depending on what kind of control components you're using, that fly-back can be damaging to the components themselves or to the power supply itself. There are ways to build in circuit protection to manage the fly-back and prevent damage.

Issue 2:

The factory Aux switches appear to "soft" switches - meaning they're not directly controlling current flow. Rather, they're sending a signal to the ECM which in turn is controlling current flow. In other words, they appear to be computer buttons, not actual "hard" switches.

Issue 1 + Issue 2:

I would hope that the FCA (now Stellantis) engineers had the foresight to expect Jeep owners to use those switches for all manners of electrical loads, including inductive loads. So I would hope that they included circuit protection for the controls. Hope. But without being certain of what kind of circuit protection exists for those switches and / or the ECM, I would still use a relay to control the compressor. That way, your fly-back current isn't traversing any of the soft components - just a relay and a fuse.

It may very well be overkill. And if enough people have already connected directly to the Aux switch outputs, then that's probably plenty of evidence to support that Jeep did it right.

You are right, hope Jeep did it right. There is a diode controlling on way current on the ARB wire lead, I also believe the aux switches also have a fuse. I will be taking what you said in consideration and I also like to be over safe then under sorry. I am really green in this area. Isnt there an on off switch at the Arb compressor? Would this be considered a relay? An in line fuse possibly. I had my Baja Design lights installed and Baja design had told the tech at the dealership to cut the fuse out of the wiring. Then again low amp item. Thanks for your write up, it gets me thinking.

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