Geotab HRN-RMRCA1 Harness: Fitment, Install and Specs

What Is the HRN-RMRCA1?

The HRN-RMRCA1 is a CAT-specific adapter for the Geotab GO RUGGED, and it only works in combination with the HRN-GR09K1 universal rugged T-harness kit. It is short, at 10 cm (4 in), and acts as the piece that turns a general-purpose rugged installation into one suited to Caterpillar equipment.

The reason a separate adapter exists comes down to wiring. Geotab notes in its harness guide that CAT engines can use different pinouts, connectors and engine data than the standard heavy-duty arrangement. A harness that is correct for an on-road truck may not line up with what a CAT system expects. Rather than build an entirely separate rugged kit, Geotab supplies this small adapter to work alongside its universal one.

The adapter sits between the CAT connection and the HRN-GR09K1, adding only 10 cm to the run.

Which Vehicles and Devices Does the HRN-RMRCA1 Work With?

Geotab describes the HRN-RMRCA1 as a CAT adapter for the GO RUGGED device, with the HRN-GR09K1 listed as a requirement. The GR09K1 is a universal heavy-duty T-harness built to IP67 with four numbered mounting adapters, intended for spots where a 9-pin diagnostic port is exposed to the weather. The RMRCA1 is what makes that kit suit CAT equipment.

Geotab does not list a part that the adapter replaces, and it does not publish a model year range for it. That makes the physical connector the deciding factor. For CAT vehicles from 2016 onward that use a 14-pin connection, Geotab offers a different part entirely, the HRN-DC14T1. Our technicians look at the connector itself before picking between the two.

What Problem Does It Solve on the Job?

Equipment owners rarely run one brand. A site might have CAT loaders beside other makes of excavators and a couple of on-road dump trucks. A fleet that standardises on the HRN-GR09K1 for its rugged installs can keep that same kit on the shelf and add the 10 cm adapter only for the CAT units that need it. That keeps parts ordering simple and means every rugged install shares the same mounting adapters and sealing standard.

The adapter also protects data quality. Plugging a generic harness into a connector with a different pin layout can leave the device with no engine data, or with power but no communication. Using the part Geotab built for CAT wiring avoids that guesswork, so engine data reaches MyGeotab rather than just a location dot.

How Is the HRN-RMRCA1 Installed?

Geotab does not attach separate instructions to this adapter, so the install follows the HRN-GR09K1 documentation and the general GO RUGGED rules. This is the order we work in:

Take down the device serial, the machine's unit number and the hour meter reading, and enter the serial in the database before starting.
Shut the machine down and leave the GO RUGGED unplugged while the harnesses are assembled.
Confirm the machine's diagnostic connector and its location in the cab, and confirm that the adapter route applies rather than the 14-pin DC14T1.
Join the RMRCA1 to the machine side and the GR09K1 to the adapter, then choose the numbered mounting adapter from the GR09K1 kit that suits the bracket.
Add up every piece in the chain and keep it at or under 2 m (6.5 ft). Do not add a second T-harness anywhere in the run.
Mount the device to a rigid surface with sky view, and cable tie both sides of each joint so vibration cannot separate the adapter from the harness.
Start the engine, wait for all three status LEDs to go solid, then confirm the unit returns Pass in MyInstall and that engine data appears.

Inside the cab the adapter plugs in at the diagnostic port, the GR09K1 carries the run, and the device mounts on a numbered adapter.

Spec	Detail
Part number	HRN-RMRCA1
Type	CAT-specific adapter
Compatible device	GO RUGGED (GO9 RUGGED)
Requires	HRN-GR09K1 universal rugged T-harness kit
Adapter length	10 cm (4 in)
Maximum connected cable	2 m
Country of origin	China

What Should You Watch for When Fitting It?

Order the adapter and the GR09K1 together, since one without the other leaves the install incomplete. A two-piece connection has one more joint than a single harness, so tie both sides of that joint firmly and keep it out of standing water on the cab floor. Check the connector before ordering, because a machine with a 14-pin port needs the DC14T1 instead. After start-up, look for engine data in MyGeotab, not just a GPS fix, to prove the adapter is doing its job.

Which Related Harnesses Should You Compare?

HRN-GR09K1: the universal IP67 rugged 9-pin T-harness this adapter requires.
HRN-DC14T1: the 14-pin T-harness Geotab lists for 2016 and newer CAT vehicles.
HRN-RS12S2: the weather-resistant OBD-II to 12-pin harness for machines with a 16-pin port.

What Are Common Questions About the HRN-RMRCA1?

Can the HRN-RMRCA1 be used without the HRN-GR09K1?

No. Geotab lists the HRN-GR09K1 as a requirement for this adapter, so both parts are needed for the connection.

How long is the adapter and the full stack?

The adapter is 10 cm (4 in) and the HRN-GR09K1 is 25 cm (9.8 in), so the pair adds up to about 35 cm, well inside the 2 m maximum.

Should we use the HRN-RMRCA1 or the HRN-DC14T1 on a CAT machine?

It depends on the connector the machine actually carries. The HRN-DC14T1 is the 14-pin harness Geotab lists for CAT vehicles from 2016 onward, so we check the port on site and order to match.

We supply the RMRCA1, the GR09K1 and the GO RUGGED as one package and fit them where the equipment is kept. For scheduling, call API Signal on 803-513-1009 or fill in Get a Quote.

Sources: Geotab harness list, GO RUGGED entries, HRN-GR09K1 support document, Geotab guide to telematics harnesses, GO9 RUGGED device page. GEOTAB is a registered trademark of Geotab Inc. API Signal is an independent installer and is not Geotab.

Every Geotab Harness →All 83 harnesses and accessories by part number. Get a Quote →The HRN-RMRCA1 supplied and installed on one written quote.

Geotab HRN-RMRCA1 Harness