ARB CKMA12 Air Compressor

Installation of ARB CKMA12 on-board air compressor in a 2013 FJ Cruiser.

First, carefully read the booklet that comes with the equipment. It lists tools and supplies needed as well as a checklist you can tick off as you go.

Gather the required tools and supplies, and ensure your work area is well lit.

First, find an appropriate location that is as flat as possible and will allow you to mount the compressor where it will not conflict with other engine bay bits, provides easy access to the hose coupling and access to change the air filter.

Using the mounting bracket that comes with the CKMA12, mark out where you will be drilling. I drilled with a smaller drill bit first as a pilot, re-checked the measurements with the bracket, and then drilled with the full-size bit as per the instructions. Then I touched up the bare metal with some appropriate paint.


I cut some little rubber mounting pads for each side of the mounting bracket. One to mate to the car body, and one for between the bracket and the compressor.


Mount it all up and get the nylock nuts on. Tighten them, check the compressor for how it’s all sitting, tighten them some more.



Now, rotate the compressor manifold by loosening the 10mm bolt. Rotate it with the fittings added (temporary) to check for your final coupling position. (see manual) Now, using some pink plumbers tape (high temp), or some paste, get the air “T” fitting in to the manifold, tighten with a 19mm spanner. Add the pressure stat/switch as above (with tape). Add the house coupling (with tape)



Remove your glovebox. Now take the big ARB wiring loom and poke the correct end through your firewall using an existing grommet (there are provisions), pull it through in to the passenger footwell. Head back to the engine bay and get started on terminals and relay mounting.

I cut the plastic off the ‘crimp’ terminals supplied by ARB because I wanted to solder them instead of crimp them. These will attach to the battery terminals.


Jam the wiring loom in with the existing loom behind the battery/fusebox/charcoal canister. Roughly measure where the power wires will reach and cut them to length, strip the wires, stick em in the ARB terminals, crimp, solder. Don’t forget to put your shrink tube on those wires first.


I mounted the relay right next to the compressor, up high, in an existing threaded hole. I taped up all exposed ARB loom wiring, including the extra connectors not used for my installation (plugs for diff locker solenoids). See pic above..

another battery / wire pic


get your wiring from inside the glovebox area and route it towards the centre console where you will be fitting the switch (unless you want the switch elsewhere)


See other guides on how to get your centre console and glovebox apart

Get your file or other cutting tool and make the switch hole bigger for the ARB switch


Switch test fitted. Note, I also moved the factory switches next to each other (required a little filing as each switch is keyed)


Terminate your wiring as per the ARB manual. I took illumination and acc feeds from the existing switches/cig lighter, I daisy-chained the connectors with some crimp bullets so I can add more things later. I picked up the illumination feed off the green wire on one of the factory switches (can’t remember which one). Sorry no pics of this.

Connect up the power wires to the battery, flick the acc on and flick the compressor switch, it should turn on for maybe 1-2 sec then off again. If it does this, great, your compressor works, and so does the pressure switch.

Pumping up some tyres


Thats about it. The plastic cap that comes fitted to the pressure switch will fit on the hose coupling to protect it from dust when not in use.

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