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The HRN-CW03S3 harness is installed in vehicles or assets where no diagnostic port is available, due to the age or type of vehicle. It has three wires that connect to power, ground, and ignition. The HRN-CW03S3 is used with a GO device.HRN-CW03S3 24 Jul '14.jpg

The HRN-CW03S3 harness connects to any vehicle, providing GPS tracking (for GO6 or newer devices), accelerometer data (on Pro and ProPlus plans), and ignition voltage (for GO7 or newer devices). Typically used in vehicles manufactured without an OBDII connector before 1996 (Golf Cart, Bulldozer, Gator, etc.), the HRN-CW03S3 does not gather engine data.

Note: The GO6 does not have an ignition pin and, as a result, behaves in the same manner with a 3-wire installation as with a 2-wire installation. Specific installation instructions below.

HRN-CW03S3 Specifications and Installation

Professional Installation Required — Installation of the HRN-CW03S3 requires the installer to have sufficient technical knowledge and expertise for mobile device installation and integration into modern vehicles, i.e. Certified Geotab® Installer certification or equivalent.

WARNING! Prior to HRN-CW03S3 installation, read and follow GO device installation instructions ( to ensure GO device installation is correct in preparation for HRN-CW03S3 installation. Incorrect installation of either the GO device, and/or HRN-CW03S3 can result in loss of vehicle control and serious injury.

WARNING! Prior to HRN-CW03S3 installation, read and follow Important Safety Information and Limitations of Use, located at the end of the document. Always read and follow all safety information to prevent loss of vehicle control and serious injury.

Installing the HRN-CW03S3 with a GO7 or newer

There are three connection wires when using the HRN-CW03S3:

  • BLACK — the GROUND wire; it must be connected to a known good chassis ground.
  • YELLOW — the ignition sense wire; it must be connected to a true ignition source (live with the key in both the ON and RUN positions, dead when the key is off)
  • RED — the constant power (12V or 24V) wire; it must be connected to a true battery source (live at all times).

The red and yellow wires must connect to a fused source, or the user must install the fuses.

Installing the HRN-CW03S3 with a GO6

Tape off the ignition wire and leave unconnected. If you do not plan to reinstall the HRN-CW03S3 with a GO6, de-pin or cut off the YELLOW wire of the HRN-CW03S3.

Detecting Ignition Using the HRN-CW03S3

If an asset is installed with a GO7 or newer device, and is using the HRN-CW03S3 with all 3 wires connected properly, the device detects the ignition wire and  uses it for ignition sensing.

If an asset is installed with a GO6 and an HRN-CW03S3, the GO6 defaults to ignition detection using accelerometer movement and GPS position changes. The asset marks the ignition state as being On, if the asset detects the vehicle’s motion. This is not as accurate as determining ignition from connecting to the ignition source and cannot be used for idling or similar purposes.

2-wire is an alternate method used by the GO6. The GO6 attempts to determine ignition based on voltage patterns along with GPS and accelerometer readings. This should only be used with GO6 devices where the aforementioned method does not provide the required accuracy. 2-wire ignition sensing requires a set parameter. If this method is required, please contact Support.

Important Safety Information and Limitations of Use

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WARNING! Do not attempt to install, reconfigure or remove any product from any vehicle while the vehicle is in motion or otherwise in operation. All installation, configuration or removal must be done only in stationary vehicles which are securely parked. Attempting to service units while being operated could result in malfunctions or accidents, leading to death or serious personal injury.

WARNING! If at any point after a Geotab in-vehicle device is installed, a warning light illuminates on the vehicle dash or the vehicle stalls or has a marked drop in performance, shut off the engine, remove the device, and contact Geotab support.

WARNING! Do not attempt to remove Geotab in-vehicle devices from the vehicle in which they are originally installed for installation in another vehicle. Not all vehicles are compatible with Geotab in-vehicle devices, and doing so may result in unexpected interactions with your vehicle, including sudden loss of power or shutdown of the vehicle’s engine while in operation or cause your vehicle to operate poorly or erratically.

WARNING! All in-vehicle devices and related cabling must be securely fastened and kept clear of all vehicle controls, including gas, brake and clutch pedals. You must inspect devices and cabling on a regular basis to ensure all devices and cabling continue to be securely attached. Loose cabling or devices may impede the use of vehicle controls, resulting in unanticipated acceleration, braking or other loss of vehicle control, which could lead to death or serious personal injury. Improperly fastened in-vehicle devices may detach and impact operators upon sudden acceleration or deceleration, which may cause injury.

WARNING! Geotab requires the use of a cable tie when securing the GO device or any extension harness to the OBD connector, securing both sides of the harness. If you do not use a cable tie, vibration in the vehicle can lead to a loose connection which could indirectly cause the vehicle’s engine computer to fail. This could result in the vehicle stalling and can even cause personal injury under certain circumstances if it occurs while the vehicle is being driven.

WARNING! Geotab in-vehicle devices must be kept clear of debris, water and other environmental contaminants. Failure to do so may result in units malfunctioning or short-circuiting, causing a fire hazard.

NOTICE — Geotab products do not contain any user-serviceable parts. Configuration, servicing, and repairs must only be made by an authorized Geotab reseller or installer. Unauthorized servicing of Geotab products will void your product warranty. Improper installation may also lead to short circuits and the risk of fire, leading to personal injury or significant damage to your vehicle. Installation or servicing may also require modifications to your vehicle. Failure to comply with specified procedures or without adequate knowledge of the vehicle may result in damage to your vehicle, which may cause malfunctions of vehicle controls or vehicular environmental systems and result in personal injury.

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