The ultimate guide to Geotab harnesses

Download the free Geotab Telematics Harness Cheat Sheet - See the list of most popular Geotab Harnesses and learn the Do's and Don'ts of installation.

By Sujay Ruthraraj

December 18, 2023

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4 minute read

There are many different types of vehicle makes, models, and sizes, made in different places around the world. The OBD II (On-board diagnostics) port may also vary in size and position from vehicle to vehicle. When using this port to install a telematics device, an adapter harness is required to ensure a proper connection. Geotab has developed a range of telematics harnesses which can accommodate installations with different vehicle types and connectors.

When is a telematics harness required?

The great thing about Geotab GO devices is that they plug directly into the vehicle’s OBD II port. However, a harness is sometimes required to make a connection possible. Reasons a vehicle may need a harness include:

To install the telematics device out of the way and out of sight
To keep the OBD port free
To connect to a 6-pin or 9-pin port
To connect the Geotab telematics device but still keep the OBD port available for use, such as for a scan tool or IOX Add-On

Types of harnesses

Geotab offers harnesses in different shapes and sizes to match as closely as possible the various Original Equipment Manufacturer (OEM) OBD connectors that can be found in vehicles.

In general, you may find these main types of diagnostic interfaces in your fleet vehicles: OBD 16-Pin, 6-Pin, and 9-Pin.

Visit the Installation Documentation page on our website to access our Geotab Harness Guide, which identifies all telematics harnesses currently available along with special order models. Depending on the harness, it may also lists the description, harness length, purpose, Geotab GO devices supported, and other details.

Geotab classifies harnesses into five categories:

OBD
Deutsch Connector for Heavy-Duty installations
European Heavy Goods for EU markets
Custom Harnesses for multiple connection points or wires, weather resistant types, and unique global vehicle models
Special Order Harnesses

Geotab has developed custom harnesses in the past when there was a large enough demand. If you require a harness for a specific application, please email the Geotab Sales Team: salesteam@geotab.com

Geotab’s Universal T-harness Kits

To simplify purchasing and installation for customers, Geotab offers two Universal T-harness Kits, one for vehicles with an OBD II port and one for Heavy-Duty vehicle applications. The kits include different mounting adapters, eliminating the need to know the types of vehicles in a fleet prior to installation.

Universal Heavy-Duty T-harness Kit

The Universal Heavy-Duty T-harness Kit (HRN-GS09K2) includes a 9-pin T-harness and a set of four mounting adapters (with Adapter 1 pre-installed) for use in most international heavy-duty vehicles. The HRN-GS09K2 will replace the HRN-DR09T2, HRN-DS09T2, and HRN-DN09T3 harnesses which will be discontinued once stock runs out.

See also:

Universal OBD II T-harness kit

The Universal OBD II T-harness Kit (HRN-GS16K22) consists of a T-harness and 12 different mounting adapters for use in most Light-Duty and Medium-Duty vehicles, and is compatible with most models globally. The Universal Kit replaces five Geotab harnesses: HRN-BE16T2, HRN-BF16T2, HRN-BG16T2, HRN-BS16T2, and HRN-BT16T2. Using a single type of harness for all of these applications is extremely helpful for fleets.

Watch the YouTube install video for the Universal OBD II T-Harness Kit.

Most popular Geotab harnesses

The following table lists our most popular harnesses. A more in-depth and larger list can be found on our harness identification page.

Note: In the Geotab Harness Naming Convention, all harnesses names start with the prefix “HRN” followed by 6-characters. All characters are alphanumeric and no I’s or O’s are used to avoid confusion.

Example: HRN-DS09T2

D represents a Deutsch connector
S represents a Standard OBD, Deutsch, or FMS connector
09 represents 9 pins / wires
T represents a T-harness
2 represents a length in the range of 12-24 inches or 30-60 cm

Harness Name	Type	Description
HRN-BD16S5	T-harness	Harness for ALDL installations for gas and/or OBD vehicles (i.e. GM, Ford, etc.) and Freightliners with gateway. This harness is one of several Geotab continuously connected aftermarket parts solutions that is compliant for use in the California market, having been granted an Executive Order by the California Air Resources Board (CARB). For more information, visit our solutions page.
HRN-DC09T2	T-harness	Designed specifically for Heavy-Duty vehicles with a CAT motor with different pinouts, connector, and engine data received.
HRN-DR09T2	T-harness	For Heavy-Duty vehicles that have a 9-pin Deutsch connector. This harness connector is threaded for the specific type of mounting bracket that requires the connector to screwed into the mounting bracket. Also comes with a locking nut.
HRN-DS06T2	T-harness	For Heavy-Duty vehicles that have a 6-pin Deutsch connector. Unlike the HRN-DR08T2, this harness connector has a flanged connector which allows it to be securely fitted with 4 screws, instead of being screwed in.
HRN-DS09T2	T-harness	For Heavy-Duty vehicles with 9-pin Deutsch connector. Identical to the HRN-DR09T2 except for the connector type. This harness has a connector with a flange that allows it to be securely mounted with 4 screws.
HRN-GS16K22 / HRN-GS16K22-A	Universal OBD II T-harness Kit	The HRN-GS16K22 harness is intended for most light-duty, medium-duty and some heavy-duty vehicles (outside North America). For North American heavy-duty trucks, always use a vehicle-specific harness when offered by Geotab or the vehicle manufacturer. This harness is one of several Geotab continuously connected aftermarket parts solutions that is compliant for use in the California market, having been granted an Executive Order by the California Air Resources Board (CARB). For more information, visit our solutions page.
HRN-GS09K2 / HRN-GS09K2-A	Universal Heavy-Duty T-Harness Kit	The HRN-GS09K2 is an installation kit that includes a 9-pin T-harness and a set of four mounting adapters (with Adapter 1 pre-installed) for use in most international heavy-duty vehicles. Eliminates the need to know vehicle information in advance. This harness is one of several Geotab continuously connected aftermarket parts solutions that is compliant for use in the California market, having been granted an Executive Order by the California Air Resources Board (CARB). For more information, visit our solutions page.
HRN-GR09K1 / HRN-GR09K1-A	Universal rugged heavy-duty T-harness kit	The HRN-GR09K1 is a ruggedized Deutsch T-harness kit with four mounting brackets for connecting a Geotab^® GO RUGGED device to most heavy-duty vehicles internationally. The HRN-GR09K1 contains four mounting adapters, which are engraved with numbers for easy reference. This harness is built to IP67 standards for protection against dust and water.

How to maintain data integrity when using a telematics harness

A proper vehicle connection is critical to ensuring quality data. Here are five quick do’s and don’ts to keep in mind when using your harness.

✔ Select the right harness for the vehicle.

✔ Follow the recommended installation procedure.

✔ Where indicated in the Harness Guide, you can connect a straight harness to a T-harness or another straight harness if a longer length is required.

✖ Do not connect two T-harnesses together, regardless of the length.

✖ Do not exceed the total harness length of 2 meters (6.5 feet). Connecting two harnesses that exceed 2 meters can compromise the integrity of the data and potentially cause issues with the vehicle’s engine control unit (ECU).

Future developments

Geotab continues to look for ways to make the harness selection and installation process easier for our customers. Since most of our customers prefer to use T-harnesses, our automotive team continuously works to match the connector type to that of the OEM connector. The development of the Universal T-harness Kits is an example of how we try to build in innovation in every part of our Geotab solution.

Have a question about harnesses or installation? Visit the Geotab Community Forums or consult the Support Documentation online.

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