Mastering Geotab
★ Geotab Harnesses · Make-Specific and Custom Harnesses
The HRN-CM24Y1-A is a short 20 cm (8 in) Geotab base harness that gives a GO device several Molex connection points, so make-specific adapters for trucks like Volvo, Mack, Hino and Isuzu can plug in. It is never installed by itself.
The HRN-CM24Y1-A is a base harness for custom Geotab installs, a short 20 cm (8 in) hub that sits between the GO device and a make-specific adapter. On one side it has an ALDL connector that the GO device plugs into. On the other side it offers a set of Molex connectors, each with a defined job, so whichever vehicle adapter the truck needs can connect to it.
Geotab's cheat sheet is clear that it is never used on its own. It is the common half of a two-part install: the HRN-CM24Y1-A stays the same, and the second harness changes with the truck. Geotab also lists it as a requirement for the custom HRN-CW08K4 8-wire kit. It replaces the earlier HRN-INTCPDUAL.
Its reach is defined by the adapters that plug into it. Geotab publishes vehicle-specific install guides that use this base harness for 2004 to 2018 Volvo, 2006 to 2018 Mack, 2016 to 2018 Hino, 2019 Hino, 2019 and newer Mack, 2019 and newer Volvo, the 2019 and newer Mack MR series cab over, 2017 and newer Isuzu diesel trucks, and the 2020 Mercedes Sprinter 2500 on a GO9.
The cheat sheet names its usual partners: the HRN-CE10K2 for 2019 and newer Mack and Volvo, the HRN-CK10K2 for 2013 to 2018 Mack, and the HRN-CI04A2 for Isuzu. For Isuzu N-series trucks from 2017 to 2024, Geotab says the base harness must be ordered together with an FMS kit. Geotab's Volvo and Mack bulletin offers a second route on those trucks as well: the HRN-GS16K22-A paired with the HRN-CG13S1-A.
On the device side, the connector list matters. The second 6-pin Molex is for J1939 and is only used with GO7 and GO8 devices, so a newer GO device relies on the OBD connections instead.
On the trucks in Geotab's guides, the connection points sit in or near the fuse panel and change by make and model year, so one complete harness per combination would be impractical. Geotab's answer is this split design: a standard hub plus a small adapter that matches the truck.
For a fleet, the benefit is fewer wrong parts. Our technicians carry the base harness as a constant and pick the adapter by make and year, which is far easier to get right than hunting for one specialist harness per truck.
The exact sequence depends on the vehicle guide, and we follow the one for the truck in front of us. Geotab's 2004 to 2018 Volvo guide is a good illustration. With the truck parked and the key off, the HRN-CM24Y1 is connected to the GO device, the device is zip-tied to the harness, and two more zip ties hold it to the fuse box frame.
The white 6-pin Molex on the vehicle adapter then mates with the white 6-pin Molex on the base harness; both are labelled for the OBD connection. On 2004 to 2007 Volvo trucks without the 2-pin gray J1939 connector, the guide adds a step: the adapter's 2-pin black connector goes into the 2-pin black connector in the top passenger corner of the fuse box, and the adapter's black 12-pin Molex joins the matching 12-pin on the base harness. Wiring is then bundled with zip ties so no fuse is blocked, the installation check is run, and the fuse box cover goes back on. Geotab's GO9 guides also require the GPS antenna side of the device to face skyward.
The general rules still apply: total connected harness length no more than 2 m (6.5 ft), no T-harness connected to another T-harness, and every device and cable fastened with cable ties. We confirm the unit is reporting in MyGeotab and MyInstall before closing the panel for good.
| Spec | Detail |
|---|---|
| Part number | HRN-CM24Y1-A |
| Type | Base harness for custom, multi-connection installs |
| Length | 20 cm (8 in) |
| Device connector | ALDL |
| Vehicle-side connectors | White 6-pin Molex (OBD 1), black 12-pin Molex (OBD 2), 6-pin Molex for J1939 (GO7 and GO8 only) |
| Replaces | HRN-INTCPDUAL |
| Used with | HRN-CE10K2, HRN-CK10K2, HRN-CI04A2 and other make-specific adapters; required by HRN-CW08K4 |
| Max connected cable length | 2 m (6.5 ft) |
| Country of origin | Taiwan |
Order the adapter and the base harness as a pair; arriving with only one stops the job cold. Match Molex colors and labels exactly, since a white 6-pin and the J1939 6-pin are easy to confuse in a dim fuse panel. Keep all bundled wiring off the fuses so a later fuse swap does not mean cutting ties. For Isuzu N-series trucks from 2017 to 2024, remember the FMS kit requirement. Pull up the Geotab guide for the specific make and year before starting, because connector steps differ even between model years of the same brand.
No. Geotab treats it as an adapter component that always pairs with a second, make-specific harness such as the HRN-CE10K2, HRN-CK10K2 or HRN-CI04A2.
An ALDL connector for the GO device, a white 6-pin Molex and a black 12-pin Molex for two OBD connections, and a second 6-pin Molex for J1939 that applies to GO7 and GO8 only.
It replaces the HRN-INTCPDUAL.
API Signal supplies the HRN-CM24Y1-A, the correct adapter for each truck and the GO device, and our technicians install them on site at your yard. Call 803-513-1009 or use Get a Quote and list your makes and years.
Sources: Geotab Harness Identification and Application, Geotab harness cheat sheet, Geotab 2004 to 2018 Volvo install guide, Geotab 2019 Mack install guide, 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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