Geotab HRN-CI04A2 Harness

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What Is the HRN-CI04A2?

The HRN-CI04A2 is a Geotab adapter that collects engine data from the FMS port on 2017 and newer diesel Isuzu trucks and passes it to a GO device through the HRN-CM24Y1-A. Geotab lists it at 30 cm (12 in), and it is only half of the requirement: the truck also needs Isuzu's optional FMS kit in place.

That dependency is the whole story with this part. The adapter does not create an FMS port; it plugs into one that Isuzu supplies. A truck ordered without the FMS option, or one where the kit has never been fitted, is not ready for this adapter until that factory hardware is sorted. Knowing this before the install day saves a wasted trip and a frustrated fleet manager.

Which Vehicles and Devices Does the HRN-CI04A2 Work With?

Geotab lists the adapter for Isuzu vehicles from 2017 onward and restricts it to diesel engines. Its Isuzu install guide adds a practical fit test: the truck should be an N-series with RPO code I4H. That code is the quickest way to tell from paperwork whether a given truck is a candidate.

Two other parts must be present. Geotab requires the HRN-CM24Y1-A, which carries the GO device connection. And the truck needs Isuzu's FMS kit; Geotab's guide refers to kit number 8983519390, made up of a bracket, four screws, a CAN interface converter module and a CAN interface converter harness. The guide connects the adapter to a GO9 through the base harness.

What Problem Does It Solve on the Job?

Isuzu N-series trucks are a staple of landscaping, delivery and service fleets. When a fleet wants engine data and not just location, the question becomes where the data comes from. Isuzu's answer on these trucks is the FMS port, and the HRN-CI04A2 is Geotab's matching connection to it.

The result is a tidy install behind the dash that leaves the diagnostic connector alone. Getting the FMS kit question answered at quote time is the real value here: a fleet with twenty trucks can find out in advance which units already carry the kit and which need it, and plan the work in one visit instead of three.

How Is the HRN-CI04A2 Installed?

Geotab's Isuzu diesel guide lays out a short sequence, and Isuzu's own Body Builder Guide holds the factory detail:

1. Confirm the truck: diesel, 2017 or newer, N-series with RPO code I4H, and Isuzu's FMS kit present.
2. Park the truck with the ignition off and the GO device disconnected.
3. Remove the dash panel, then the two panels or compartment holders to the right of the radio. Geotab's guide notes the CAN interface converter harness is kept in the passenger-side glove compartment.
4. Connect the HRN-CI04A2 end that is not marked OBDII to the FMS module.
5. Connect its OBDII-marked end to the matching OBD-II end of the HRN-CM24Y1-A.
6. Plug the GO9 into the HRN-CM24Y1-A and use the remaining cable to reach a suitable mounting spot, GPS antenna side facing the sky. Fix it with cable ties.
7. Run the install check, confirm the truck reports in MyInstall and MyGeotab, then put the panels back.

The connected harnesses must total 2 m (6.5 ft) or less, and no T-harness can feed another.

Which Related Harnesses Should You Compare?

• HRN-CM24Y1-A: the base harness this adapter cannot run without.
• HRN-CH10A2: Geotab's 10-pin adapter for newer Hino trucks, another make-specific medium-duty connection.
• HRN-BU16Y5: an OBD-II harness with an extra connector for Mitsubishi Fuso and medium-duty engine data.

What Are Common Questions About the HRN-CI04A2?

Will the HRN-CI04A2 work on a gas Isuzu?

No. Geotab limits it to diesel Isuzu vehicles from 2017 on, and its guide adds that the truck should be an N-series carrying RPO code I4H.

What is the Isuzu FMS kit and do we have to buy it separately?

It is an Isuzu option that provides the FMS module the adapter plugs into. Geotab's guide lists it as kit 8983519390, with a bracket, screws, a CAN interface converter module and its harness. If the truck does not already have it, it has to be sourced before the install.

Which end of the HRN-CI04A2 goes where?

The end not marked OBDII goes to the FMS module, and the end marked OBDII joins the matching OBD-II end of the HRN-CM24Y1-A.

Isuzu fleets get a straight answer from us on the FMS kit before any truck is booked. API Signal then supplies the HRN-CI04A2, the base harness and the GO devices and installs everything on site at your yard. Talk to us at 803-513-1009 or open a request on Get a Quote.

Sources: Geotab Harness Identification and Application, Geotab Isuzu diesel install guide. GEOTAB is a registered trademark of Geotab Inc. API Signal is an independent installer and is not Geotab.