Support Document

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Jun 21, 2022


With over five million medium and heavy trucks (commercial trucks) on the road in North America, the truck industry represents a significant opportunity for our Partner base. Today, Geotab supports over 600,000 commercial trucks in the North American market, and that number continues to grow.

The sales process for commercial vehicles ranges from simple to very complex, but regardless of the complexity of the opportunity, one decision that every Partner needs to make is what connector to use when installing the GO device. For the commercial truck market, our Partners typically have the option of utilizing the standard On-Board Diagnostics (OBD) connector (9-pin or 16-pin), depending on the OEM, or the standardized data-only RP1226 connector. This document outlines the advantages and disadvantages of the RP1226 connector.


The vast majority of commercial trucks use the SAE J1939 electrical architecture developed by the Society of Automotive Engineers (SAE). The simplest way to think of SAE J1939 is as a backbone, with various modules that can be attached to the backbone. Modules can include an engine controller, a transmission controller, a brake controller, a Geotab GO device, or hundreds of other modules. The beauty of SAE J1939 is that it allows modules from different OEMs to communicate with each other utilizing an industry standard.

The Geotab GO device has historically been installed into the OBD connector to pull data from the SAE J1939 electrical system in the same way that an engine controller or transmission controller do today. The Geotab GO device enables bi-directional communication with the electrical system via the OBD port. Today, the vast majority of commercial trucks supported by Geotab use OBD to install the Geotab GO device.

With that being said, several years ago, the Truck Maintenance Council approved the RP1226 industry standard for installing third-party solutions into vehicle electrical systems in a way that is OEM approved. This standard is now available from the vast majority of OEMs.

Geotab currently supports installations via the 9-pin OBD connector, the 16-pin OBD connector, and the RP1226 connector.

NOTE: For more information, see the Everything you need to know about the RP1226 connector blog post.

Advantages and Disadvantages of RP1226


The key advantage of moving to the RP1226 connector is that it is the officially OEM-approved way for third parties to connect to the vehicle’s electrical system. If you ask an OEM, they will highly encourage you to utilize the RP1226 connector. Additionally, the RP1226 harness that Geotab supplies is compatible with all OEMs that support the RP1226 connector. This limits the amount of SKUs that a Customer or Partner has to keep track of.


The key disadvantage of the RP1226 connector is that a gateway is installed behind the RP1226 connector that limits the data that can be pulled from the electrical system, and limits the bi-directional communication capabilities of the electrical system. This has several downstream impacts:

  • If Geotab adds support for additional parameters, then vehicles utilizing the RP1226 connector may not be able to receive this data, while Customers using the 9-pin or 16-pin OBD connector would not be impacted.
  • Geotab is in the process of working with multiple Tier 1 OEMs to provide over-the-air module updates, meaning that Geotab will be able to update engine or transmission modules with new calibrations or parameters. However, customers utilizing the RP1226 connector would be unable to leverage this new functionality due to the gateway, or would need to reinstall their GO device to the 9-pin or 16-pin OBD connector.
  • For compliance, the California Air Resources Board (CARB) Inspection & Maintenance regulation requires access to data that currently is not provided by any OEM via the RP1226 connector. This regulation is still in its early days, but as it is currently written, it will impact 1.2 million diesel vehicles that operate in California. In order to meet this regulation as it is currently written, Customers will not be able to use the RP1226 connector.
  • Future innovations and features added to the Geotab platform and firmware would likely be inaccessible unless the gateway behind the RP1226 connector was updated by the OEM. However, OEMs are under no obligation to update that gateway, and each OEM would likely handle it differently.

NOTE: The RP1226 connector is designed to support multiple persisting connected devices. Customers should pay close attention to vehicle stub lengths when daisy-chaining connections, such that the connection does not exceed 5 meters, as per J1939-15. Variable stub lengths also help preserve signal integrity, and avoid potential reflections. Hence, Geotab has designed the CS14T2 harness with nodes at differing stub lengths.


Ultimately, the end user must decide the best installation option for their truck fleet. It is exceptionally important that Partners and Customers have all the necessary information to make a decision that is right for them. Please reach out to your Partner Account Manager (PAM) if you have any questions related to using OBD or RP1226 connectors.