Your old seed drill has no switch in the cab. You want to run the work lights, fold the markers, and flip a couple of solenoid valves from your seat — without dragging a loom through the back window. That's the situation behind almost every search for an "ISOBUS retrofit kit." The real question underneath it is: how do I get my implement's functions onto the screen the tractor already has?
This guide covers what an ISOBUS retrofit actually involves, what it costs, and where the honest limits are. Here's the part most people miss up front: in most cases you're not retrofitting the tractor. You're retrofitting the implement.
What an ISOBUS retrofit actually means
When people plan an ISOBUS retrofit, they think about the tractor first. Usually it's the other way around. The tractor already has what you need — a Virtual Terminal (the screen) and an ISOBUS connector on the back. What's missing lives on the implement: the drill, the sprayer, or the trailer has no electronics that talk to the tractor.
That's where the retrofit happens. You add a relay module to the implement that speaks ISOBUS. ISOBUS Block is an 8-channel relay module built for exactly this:
- It mounts on the implement — in the Implement kit it sits inside a weatherproof IP65 enclosure.
- One cable runs to the tractor's rear ISOBUS connector.
- The implement's functions show up as buttons on the Virtual Terminal.
From there you switch up to eight outputs (CH1 through CH8) straight from the tractor screen — or, if your tractor supports AUX-N, from the buttons on your joystick and armrest. One cable in, eight loads out. No second display, no proprietary software.
Whether it works with your specific tractor is a separate question, answered in our ISOBUS compatibility guide. This post answers the other half: how you actually fit it.
Fendt, John Deere, New Holland — does the brand matter?
Short answer: no. That's the good news you rarely hear stated plainly.
The ISOBUS connector is standardized under ISO 11783. The socket on a Fendt looks the same as the one on a John Deere, a New Holland, a Case IH, or a Deutz-Fahr — it's the same 9-pin connector on every brand. So a retrofit that works on one ISOBUS tractor works on any ISOBUS tractor.
That means ISOBUS Block is not matched to a brand. There's no Fendt version and no John Deere version. There's one module, and it speaks the standard all these tractors speak. If someone tells you a retrofit kit is tuned to your brand, they're selling you a story.
The only real question isn't the brand — it's whether the tractor has ISOBUS at all. More on that below.
What the retrofit gives you on the implement
On the implement, the module switches relays. Relays switch current — to solenoid valves, work lights, beacons, and other 12/24V loads. Each channel can be set to TOG (on/off, latching) or MOM (on only while pressed). A few everyday examples:
- Seed drill: fold the markers, switch the work lights, run the fill auger. For the folding side of it, see Planter fold control from the ISOBUS screen.
- Sprayer: lighting, rinse circuit, diverter valves. For running boom sections from joystick buttons, see Sprayer boom control over AUX-N.
- Balers and harvest machines: work lights, road lighting, extra functions — all mapped to freely assignable buttons.
One point of honesty: the module replaces the control side only. It switches the relay, the relay switches the solenoid — and from there your hydraulics take over exactly as before. The hoses, the cylinders, and the oil stay as they are. ISOBUS Block does not drive a cylinder directly. It just means you switch the valve from the screen or the joystick instead of from a rocker switch bolted to the implement.
And because each channel gets its own name and icon that you set from the terminal, you don't end up with eight blank buttons. Rename CH3 to DIVERTER, give it a valve icon, and that's what shows up — on the screen and in the AUX-N assignment menu.
What does an ISOBUS retrofit cost?
The price depends on how much pre-wiring you want done for you. ISOBUS Block comes in three tiers:
| Version | Price | What's in it |
|---|---|---|
| Module | €980 | The bare 8-channel relay module in a DIN-rail housing (IP20). You supply the ISOBUS cable and, for outdoor use, your own enclosure. |
| Cabin kit | €1,090 | Module plus a pre-built 1.8 m harness that plugs straight into the in-cab ISOBUS connector. For an in-cab install. |
| Implement kit | €1,590 | Module pre-mounted in a weatherproof IP65 enclosure, with a pre-terminated ISOBUS lead for the rear connector and eight short flying leads, each ending in a 2-pin Deutsch connector. |
For retrofitting an implement that lives out in the field, the Implement kit is the one you want — the enclosure handles wet, dust, and vibration. The bare module makes sense if you have your own enclosure or you're mounting in the cab. The harness and the weatherproof enclosure only come as part of their kit, not separately, so you choose the version up front.
What your tractor needs first
For the retrofit to work, the tractor needs two things:
- A Virtual Terminal — an ISOBUS-capable screen in the cab.
- An ISOBUS connector — usually on the rear, and up front too if you run front implements.
Most mid-range-and-up tractors built from around 2010 on have both as standard. On some models ISOBUS has to be enabled by the dealer, even when the socket is already fitted.
Here's the honest limit: if your tractor has no ISOBUS at all — no connector, no terminal — then ISOBUS Block does not add ISOBUS to it. The module speaks ISOBUS; it doesn't create it. Converting a non-ISOBUS tractor to ISOBUS is a dealer-level job, not a bolt-on retrofit. So check for the socket first.
Frequently asked questions
Do I need a new monitor?
No. ISOBUS Block uses the Virtual Terminal already fitted in your tractor. Your function buttons appear on that screen. There's no second monitor to buy, and none is included.
Will it work with my tractor?
If your tractor has an ISOBUS connector and a Virtual Terminal, yes — regardless of brand. The ISOBUS connector is standardized, so it makes no difference whether you run Fendt, John Deere, New Holland, Case IH, or Deutz-Fahr. Whether your tractor also supports AUX-N for joystick button assignment is worth checking in the compatibility guide. Without AUX-N, you simply switch from the screen softkeys.
Can I install it myself?
In most cases, yes. With the Implement kit you bolt the enclosure to the implement, plug the ISOBUS cable into the tractor's rear connector, and mate the Deutsch connectors to your loads. Then you assign the buttons from the terminal. There's no ISOBUS connector to crimp — it comes pre-terminated. For the connector and its pins, see the ISOBUS connector pinout guide, and for how button assignment works on the terminal, see the AUX-N complete guide.
Retrofitting ISOBUS on your implement? The ISOBUS Block Implement Kit puts the 8-channel relay module in a weatherproof enclosure — one cable to the ISOBUS connector, eight outputs for solenoids, work lights, and more, switched from your tractor's terminal.