Mastering Geotab
★ Geotab Harnesses · Special Order, European and Accessories
The HRN-IOXEXT-A is a 2-meter extension harness that connects Geotab IOX add-on hardware to a GO device, or one IOX to another, so modules can be mounted away from the device to cut interference and clutter.
The HRN-IOXEXT-A is an extension harness for Geotab IOX hardware, 2 meters (79 inches) long, that connects an IOX add-on at one end to the GO device at the other. Geotab's stated purpose is to prevent interference and minimize obstruction: rather than stacking every module right at the GO device under the dash, the extension lets an IOX sit somewhere more sensible. It can also join two IOX devices together.
IOX modules are how a GO device grows beyond basic tracking. They add things such as driver ID readers, serial data links, extra inputs, driver feedback and connections to other on-board systems. Each one plugs into the IOX expansion port and passes the bus along to the next. When a fleet adds two or three of them, the space around the GO device fills quickly, and that is where the extension earns its place.
Geotab lists the part as TAA compliant and made in Taiwan. Beyond that, the published detail is limited, so this page keeps to the documented facts and the layout checks we use on IOX jobs.
The extension is vehicle-neutral, since it lives entirely on the IOX side of the install. What it needs is a GO device with an IOX expansion port and one or more IOX modules. Geotab's insert speaks of IOX devices generally rather than listing models. On GO RUGGED installs, Geotab requires the HRN-RX06S4 rugged IOX harness before any IOX can be added, so that harness comes first on those units.
Geotab writes its 2 m total length rule and its ban on joining two T-harnesses for the vehicle harness run. For the IOX side, the cable insert sets separate daisy-chain limits, covered below, so we keep the two budgets apart when planning.
Under-dash space is tight on most vans and pickups, and modules stacked straight off the GO device make a brick that is hard to tie down and hard to service. Geotab specifically mentions interference and obstruction. Spreading modules out lets each one sit where it is easy to secure and away from the driver's knees, the steering column and the pedal box.
It also helps when an IOX has to live in a specific place. An NFC reader belongs where the driver can reach it, and a module tied to upfit equipment may need to be closer to that equipment. A 2 m bus extension gives that reach without reworking the rest of the chain.
Geotab's insert for the cable is short, and the steps below combine it with Geotab's standard IOX practice:
| Spec | Detail |
|---|---|
| Part number | HRN-IOXEXT-A |
| Use | Extension between IOX hardware and the GO device, or between two IOX devices |
| Length | 2 m / 79 in |
| Daisy-chain limits | 1 extension: up to 5 IOX devices; 2 extensions: up to 2 IOX devices |
| Compliance | TAA compliant |
| Country of origin | Taiwan |
Geotab warns that ignoring the instructions can mean lost data and malfunctions in the IOX units further down the chain, and the usual culprits are a missing shunt or a chain longer than the limits allow. Each added extension shrinks the number of modules Geotab permits, so a second cable should be a last resort. Watch the power budget too: Geotab caps a GO9 at 2750 mA total across all IOX hardware, and each module's maximum draw has to be added up against it. Route the extension away from heater ducts and seat mechanisms, and avoid sharp bends right at the connectors.
Geotab's insert for the cable sets the limits: with one extension in the chain, up to five IOX devices; with two extensions, no more than two IOX devices. We plan the layout around those numbers before mounting anything.
Yes. Geotab says it can join two IOX devices as well as linking an IOX to the GO device, which helps when modules have to sit in different places in the cab.
Yes. Geotab requires the GO device to be disconnected from the vehicle before the harness or any IOX is installed, then reconnected afterward with its instructions followed.
API Signal supplies and installs Geotab harnesses and devices on site at the customer's yard, and we lay out IOX chains so they stay serviceable. Call 803-513-1009 or use Get a Quote to add IOX hardware to your fleet.
Sources: Geotab Harness Identification and Application, Geotab HRN-IOXEXT insert, Geotab IOX-RS232 support document, Geotab GO9 RUGGED support document. GEOTAB is a registered trademark of Geotab Inc. API Signal is an independent installer and is not Geotab.
Tell us how many vehicles and what they are. We'll quote the hardware and the install together.