I don’t really listen to the stereo when driving and after a few months of staring at the Jimny’s aftermarket head unit I began to wonder if I could fit something more useful in its place. I was drawn to the idea of an inclinometer and whilst looking for a DIN-sized version stumbled across Subaru’s Field Monitor Unit, fitted as part of a winter pack to some Imprezas & Legacys.

More useful on a day-to-day basis than an inclinometer (not hard!), the FMU is also designed to piggyback the standard Subaru stereo for power, something I was hoping to take advantage of to eliminate any wire-snipping during the installation. There happened to be an FMU complete with wiring loom and cage on eBay – immediately purchased – and an evening of Googling also uncovered the part numbers for the outside temperature sensor (H5010FC021) and sensor wiring harness (H5010FC051) which I needed to complete the setup, as well a Subaru dealer in the US (Chaplins Subaru) who could ship them over to me here in the UK.

The easiest place to mount the outside temperature sensor was by the nearside headlight, both for accurate temperature readings – it’s out of the wind but close to the grill and in front of the radiator – and because from there the loom could easily be routed back to one of the apertures in the bulkhead and through into the space behind the glovebox.

Subaru FMU temperature sensor on a Suzuki Jimny

Connecting the FMU to the Jimny’s wiring meant modifying a Parrot/Bluetooth kit adapter for a Subaru of a similar age to the FMU – cheap and plentiful on eBay and much preferred to hacking up factory wiring! Keeping the Suzuki-to-ISO adapter that the aftermarket stereo had used I snipped the single wire connecting the two halves of the Parrot adapter and connected one half up to convert back from ISO to Subaru, which could then be plugged directly into the piggyback loom.

Suzuki - ISO - Subaru wiring adapters

The FMU also has the option to display a simple animation when the car is moving – kind of retro cool but, as this requires Scotchlocking a wire to the ECU (and because I don’t really need to be told when the car is moving!), I decided to leave this bit of the installation alone.

After experimenting with the FMU’s OEM cage I decided it would easier to remove the stereo/clock/cubby hole frame from the car, mount the unit directly to it and drop the whole thing back in again. With the frame out of the car I could drill holes in the sides in order to screw into the original mounting points on the FMU itself, route the wiring loom neatly out of the back of the frame and also install a surround to tidy up the gap between the Jimny’s centre console and the FMU itself. I used Accujet for the cutting of the surround – excellent service once again – and sprayed it with black VHT Flameproof exhaust paint before baking it for a really durable, matte finish.

Subaru FMU mounting in a Suzuki Jimny
Subaru FMU in a Suzuki Jimny