Mastering Geotab
★ Geotab Harnesses · Make-Specific and Custom Harnesses
The HRN-CW03K3 is a Geotab three-wire harness kit, 90 cm (36 in) long with a fuse kit, that powers a GO9-family device on vehicles or assets with no usable diagnostic port. It wires to power, ground and ignition instead of plugging into a connector.
The HRN-CW03K3 is a three-wire power harness kit for GO9-family devices, used when a vehicle or asset has no diagnostic port to plug into. It comes as a 90 cm (36 in) harness with a fuse kit, and it gets the GO device running by wiring it to the vehicle's power, ground and ignition circuits.
The same part number appears twice in Geotab's harness list: once in the custom section for the GO9 kit described here, and once in the GO10 section, where the HRN-XCW03K3 kit is listed as its replacement. If you are ordering for GO10 hardware, that X-prefixed kit is the one you want.
Without a diagnostic connection, the GO device works from its own GPS and the ignition signal rather than reading the engine computer, so fleets get location, trips and ignition status rather than full engine data.
Geotab's cheat sheet makes it the default for vehicles with no diagnostic port, which includes all makes built before 1996. It also lists a three-wire install as the only option for some 1995 to 2008 Mercedes trucks and some 2000 to 2008 Volvo Euro 3 and Euro 4 trucks, and it points 1999 to 2009 Mitsubishi Fuso trucks on GO9 to this kit.
The device is GO9 family. For GO10 and GO10 Plus, Geotab's equivalent is the HRN-XCW03K3, which pairs a straight harness with a 5 amp fuse kit and is described for golf carts, generators and older vehicles.
Geotab's vehicle notes also mention a combination worth knowing: on certain European Mercedes-Benz trucks where a dash message appears with a standard install, one listed option is this kit with an IOX-CLAMP, with the caveat that it may not read every fault code.
Some units never fit the plug-in model: a classic truck still earning its keep, a yard tractor, a generator trailer. Without a three-wire option those assets stay off the map entirely.
The three-wire kit brings them onto the same map as everything else. With ignition wired, the device knows when the unit is running, so trips and run time are recorded rather than just position.
It also matters during hardware upgrades. Geotab warns that for 12 and 24 volt vehicles moving from a GO8 or older device to a GO9 or newer, the existing cable harness should be replaced with an approved version. On a three-wire truck, we fit this kit fresh.
Work on the vehicle parked and switched off. Pick a protected device location, then find the three circuits with a meter. Geotab's GO10 version document defines them, and the same principles apply. Constant power must come from a true battery source that is live at all times. Ground must be a known, verified ground. Ignition must be a true ignition source that reads 12 or 24 volts with the key in ON and RUN and drops to zero volts in OFF.
Make the power connection through the supplied fuse kit, connect ground and ignition, and route the harness to the device along existing wiring, clear of the pedals and away from heat. Plug in the GO device and fasten the device and harness with cable ties. Geotab's limit of 2 m (6.5 ft) for connected cable applies, and no T-harness may ever be joined to a second T-harness.
To verify, start the engine and give the device time to initialize; on GO9 devices, red, blue and green LEDs indicate ignition, GPS and cellular. Cycle the key to prove the ignition wire switches. Finish with the MyInstall check and make sure trips appear in MyGeotab.
| Spec | Detail |
|---|---|
| Part number | HRN-CW03K3 |
| Type | Three-wire custom harness kit (GO9 family) |
| Kit contents | Harness and fuse kit |
| Length | 90 cm (36 in) |
| Connections | Constant power, ground, ignition |
| Used where | No diagnostic port available, including vehicles before 1996 |
| GO10 equivalent | HRN-XCW03K3 with 5 A fuse kit |
| Upgrade note | 12/24 V vehicles moving from GO8 or older to GO9 or newer should get an approved harness |
| Max connected cable length | 2 m (6.5 ft) |
| Country of origin | China |
The ignition wire is where most three-wire installs go wrong. A circuit that stays live in accessory or drops out while cranking will produce false trips or missing ones, so test it in every key position before connecting. Take constant power from a true battery source, never from a circuit that a relay or master switch can cut. Use a clean, bare-metal ground. And if the asset's fuel level matters, plan for the three-wire fuel tap at the same visit rather than reopening the dash later.
Not on its own. It powers the GO device from constant power, ground and ignition with no diagnostic connection; Geotab lists an IOX-CLAMP pairing for some trucks where limited fault data is wanted.
No. Geotab lists the HRN-XCW03K3 as the GO10 three-wire kit that takes over from it.
When the vehicle or asset has no usable diagnostic port, such as vehicles built before 1996, or where Geotab lists a three-wire install as the only option.
From classic trucks to generators, API Signal supplies the HRN-CW03K3 and the GO device and wires them on site at your yard, ignition circuit tested before we leave. Phone 803-513-1009 to arrange it, or use Get a Quote.
Sources: Geotab Harness Identification and Application, Geotab HRN-CW03K3 support document, Geotab HRN-XCW03K3 document, Geotab harness cheat sheet, Geotab vehicle-specific installation notes. GEOTAB is a registered trademark of Geotab Inc. API Signal is an independent installer and is not Geotab.
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