Installation Guide

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September 2021

PLEASE NOTE: This document is intended for Geotab Partners or Geotab Advanced Certified Installers, and relates to the installation of Geotab products only. This document is not intended or recommended for use for any other audience, product, or purpose and Geotab disclaims all liability for such uses.

! IMPORTANT: This HRN-CX10S4 harness will only work with IOX-KEYLESS H/W: B1 or later and will not work with earlier versions of IOX-KEYLESS. Refer to Notes and Considerations for more information.

Notes and Considerations


  1. Please read the Start Inhibit Installation Use Case Considerations section before installation.
  2. The end customer assumes the risk that if they need to move the vehicle in an emergency situation, they cannot if they do not have access to a valid Geotab Keyless reservation (access via smartphone or NFC) to authorize start on the vehicle, and if the device is out of cellular coverage.
  3. The Starter Inhibit installation for Geotab Keyless is optional and is designed only for vehicles with a bladed key start. Do not install the Starter Inhibit in vehicles with push button start — the Geotab Keyless solution provides this functionality.
  4. The HRN-CX10S4 harness will only work with IOX-KEYLESS H/W: B1 or later as shown in the following sample label and will not work with earlier versions of IOX-KEYLESS. If your device label does not indicate B1 then please reach out to Geotab Support for further instructions.

NOTE: As the Partner, it is your responsibility to confirm the Installer is a Geotab Authorized Installer in good standing as per the Geotab website, certified at the Advanced Level, and they must have real-time access to the host vehicle wire interface diagrams for starter control (i.e. ALLDATA™, WireSheet™, or equivalent). Typically, the diagrams are provided to car alarm solution installers. Only this access allows Installers to:

  1. Have the means to determine which vehicle wire to interface.
  2. Understand when the Start Inhibit wire on the vehicle’s ignition switch harness is multiplexed and, therefore, must be inhibited by other means, for example within the Engine Bay, interrupting the control wire between the starter relay and the starter solenoid.
  3. Determine the Make/Model/Year of vehicle where the Start Inhibit Solution cannot be installed into.

It is your responsibility as the Partner to provide the vehicle list (Make/Model/Year & Trim) to the Installer three business days prior to the site visit.

NOTE: Geotab provides no starter inhibit guidance for Hybrid or Electric vehicles.

! IMPORTANT: As the Partner, you are responsible for ensuring that the steps outlined in this document are followed. If you are working on Internal Combustion Engine vehicles with multiplexed starter circuitry that may require wire runs from under the dash into the engine bay, it is essential to discuss interfacing details, such as best practices and firewall pass-through, for each Make/Model/Year group with the primary on-site stakeholders. The primary on-site stakeholders may include the Geotab Authorized Installer's primary contact, the client's primary contact (fleet manager), and/or the auto-shop supervisor. It is highly recommended that the client's primary contact or designate sign off on all related installations.


The integration and installation of the Start Inhibit feature to remotely inhibit the start of vehicle ignition is a complex undertaking. This document intends to highlight and elaborate on the implementation of the Start Inhibit feature, and support any challenges the Installer may face.

Geotab provides an initial list of issues that the Partner and Installer should consider when planning the Start Inhibit feature integration and installation. The list, although not exhaustive, is created to broadcast the complexity of issues to consider for the integration and installation of the Start Inhibit feature. The aftermarket Partner and Installer must consider additional issues when designing a Start Inhibit feature for a specific vehicle. For example, cutting vehicle wires for some in-vehicle installations.

Geotab also provides a hypothetical Start Inhibit implementation for an unspecified vehicle to demonstrate the combined functionality of the GO device, IOX-KEYLESS, and HRN-CX10S4 relay harness in this use case (i.e. remote start of vehicle). The steps for Start Inhibit feature installation are meant to provide general installation guidelines.


  1. Geotab is aware that many aftermarket solutions — some offered by Geotab Partners — currently meet the Starter Inhibit Device (SID) use case demand. Due to the vehicle-specific nature of each installation, the party that performs the feature integration and installation must also be the party responsible for any ongoing troubleshooting and end user support.
  2. Geotab does not prohibit Partners or parties subcontracted for installation from providing a solution for this Start Inhibit use case (i.e. remote start of vehicle). Due to the wide variety of installations and vehicles, Geotab cannot provide direct support for this use case outside of the GO device and detection of peripheral IOX hardware (i.e. installation, use, maintenance, or verification for Start Inhibit use cases outside the scope of Geotab Support).

Start Inhibit Installation Use Case Considerations

Geotab acknowledges the growing significance of the Start Inhibit feature to prevent unauthorized vehicle use — as demonstrated through Car Share programs. Currently, Geotab does not have an engineered solution for Start Inhibit installation suitable for all vehicle Makes/Models/Years. However, research and development of a product intended for this particular use case is in progress.

Proprietary OEM Start Inhibit Functionality

Some vehicles provide a dedicated Start Inhibit interface that can be within a designated Programmable Special Module (PSM), a dedicated de-rate or shift lock PIN, and in some vehicles can be provided in another location. Start Inhibit installers must be very familiar with the specific vehicle prior to planning the Start Inhibit installation.

Limp Mode Substitution

Some vehicles have a dedicated limp mode interface that provides limited vehicle functionality, normally low speed, and ratchet speed lower over time. The limp mode feature is designed for cases when vehicles have self-diagnosed and determined it is not safe to travel at full operating speed, and must be driven to the nearest service station. In some cases, the limp mode may meet end user Start Inhibit requirements.

Impedance Monitoring on Select Circuits

Some vehicles may be designed to indirectly affect vehicle drivability or introduce other problems, if monitored vehicle wires are cut. In these specific vehicles, there is a secondary signal within the vehicle communication that measures the original circuit impedance, and — if modifications are made to the circuit — the vehicle Engine Control Unit (ECU) recognizes an error. If this occurs, the vehicle may go into limp mode or display an error / vehicle service indicator message.

Internal Combustion Engine (ICE) Start/Stop Functionality

Some vehicles stop the engine every time the vehicle comes to a stop and automatically restarts the engine upon pressing the accelerator pedal. The Start Inhibit installers in these vehicles need to ensure that the activation of the Start Inhibit feature does not disable the vehicle in a precarious location such as a busy intersection. They must also ensure that installation and activation does not leave the vehicle unable to move to a safe location, or produce any direct/indirect effects.

Start Inhibit Installation

The HRN-CX10S4 harness — a four-wire expansion harness — allows installers to gain access to the Start Inhibit capabilities of the IOX-KEYLESS H/W: B1 and newer as indicated by the label on the unit with “H/W: B1”. The HRN-CX10S4 harness comes with a standard 12V automotive relay with the Common (C) and Normally Closed (NC) contact wires, which allows the IOX-KEYLESS to inhibit the starter on a vehicle and mitigates unauthorized use and potential vehicle theft.

! IMPORTANT: The HRN-CX10S04 harness must NOT be used with previous versions of the IOX-KEYLESS and only the HRN-CX10S04 harness can be used with the H/W: B1 version of the board. Not doing so may damage the boards.

HRN-CX10S4 Relay Background

The relay installed on the HRN-CX10S4 (as shown above) is a standard Form-C automotive relay with a wired Common 30, a wired Normally Closed 87a, and a Normally Open 87 relay that has no wire. The relay, when activated, allows the harness wires to break the circuit they are connected to.

The relay is triggered by the IOX-KEYLESS upon reception of a command to enable or inhibit the starter. Starter Disable activates the relay coil, therefore opening the Normally Closed contact so the vehicle does not start, while Starter Enable deactivates the relay coil, ultimately closing the original circuit allowing vehicle to start.

Harness Technical Specifications

The technical specification of the harness is outlined in the table below.


Max Length: 1350 ± 35 mm

Max Width: 15.8 mm


10 Position Connector: PBT

Wire Jacket: Thermoplastic

Labels: Polylyte/LP-50


1 x 10 position connector

Current Draw IOX-KEYLESS H/W B1 (and newer) on GOx daisy chain not taking into account the harness current draw

55 mA at 8 V/ 49 mA at 12 V / 24 mA at 24 V Operating mode (typical/nominal current draw)

0.81 mA at 8V/ 0.59 mA at 12 V / 0.38 mA at 24 V Sleep mode (min. current draw)

Vehicle Interface Wires

  1. IGN +12/24V 5A (fuse)
  2. Ground
  3. From key starter
  4. To starter motor

Relay Contact Rating (Max)

30A at 14 VDC / 15A at 27 VDC

Wire Gauge (AWG) and Max current of relay Common & NC wires

14 AWG 20 Amps at 75 C

Temperature Rating

−40 to +85 °C

Example of Start Inhibit Harness Installation Instructions


Preview the vehicle list (Make/Model/Year) that your Partner provided against your host vehicle wire interface diagrams for starter control (i.e. ALLDATA™, WireSheet™, or equivalent) to determine which vehicle functions are to be enabled or disabled when the relay is activated. This helps you determine which vehicle wire(s) must be cut and therefore where the secondary relay harness wires (Common 30 and Normally Closed 87a) must be connected.

In this example, the (BLU) START wire at the ignition switch allows the car to be started when the key is turned to the START position. The IOX-KEYLESS is intended to interrupt this wire to control when the vehicle can and cannot be started.


    1. Unless otherwise stated, only one relay is required for Start Inhibit. Under very special conditions one of two additional standard automotive 12 volt (coil) relays can be added and controlled by the wires labeled Output 1 and Output 2.
    2. End to end installation testing can only be performed after all GO9 and IOX-Accessory firmware has been updated. This typically takes five minutes, but can take longer in areas with poor cellular coverage such as rural areas or in a shop. All three LEDs on the GO9 will turn solid and the device beeps 10 times when the firmware update is complete. Therefore Installers may choose to perform a temporary install while removing vehicle dash panels and performing their initial stages of Start Inhibit install, by connecting all IOX-Accessories to the GO9 and then temporarily plugging the GO9 into the OBD port and turning the vehicle engine on for two minutes. After all three LEDs have gone solid, you may remove the GO9 and complete your full installation procedure.

  • HRN-CX10S4 Key Elements

    The following table outlines the schematic for this example:



    In-Vehicle With Photos Step


    HRN-CX10S4 10 Pin Connector connecting to IOX-KEYLESS



    Chassis ground



    (30 C) Starter Inhibit Relay wire — black start switch side



    (87a NC) Starter Inhibit Relay wire — white/black starter side



    Ignition (Vehicle true Ignition, capable of sourcing power for relay(s) via active electronic switch within the IOX-KEYLESS)



    Starter Inhibit Relay and Socket assembly


    In-Vehicle With Photos


    1. Locate the starter wire in the vehicle.
    2. ✱NOTE: Using a digital voltmeter, locate the starter wire — This wire will test at +12 or +24 volts — only when the ignition switch is in the START position.

      This is the blue/white wire in this example.


    1. Cut the starter wire in a place leaving sufficient length for connection.
    2. This is the blue/white wire in this example.

  • 3

    1. Connect (C) the black wire from the starter inhibit relay to the switch side of the cut starter wire.
    2. Connect (D) the white/black wire from the starter inhibit relay to the starter side of the cut wire.
    3. The starter wire is the blue/white wire in this example.

      ! IMPORTANT: All starter connections are required to be soldered and insulated using heat shrink tubing.

  • ✱ NOTE: A completed connection, when soldered and insulated with heat shrink, should look similar to this image.


    1. Connect (E) fused yellow wire to a true ignition source (12 V/24 V). This ignition source is used to energize the relay and must be able to source ~100 mAmps.
    2. Do not connect to an ECU Ignition sense wire.

      ! IMPORTANT: This wire should have +12 or +24 volts when the ignition switch is in the ON and START positions, and should have 0 V when the ignition switch is in ACC or OFF positions.

      In this example the orange/white wire is the suitable vehicle ignition wire.

      ✱ NOTE: Do not connect the yellow wire directly to the vehicle’s battery. This will result in constant draining of the battery if the relay is energized.

  • 5

    1. Connect (B) black wire from the starter inhibit relay to a chassis ground. A self-tapping screw can be used to secure the ring terminal to a part of the metal dash frame.
    2. ! IMPORTANT: Verify there is no wiring or object behind the location of the ring terminal prior to drilling.

  • 6

    1. Plug (A) 10 pin black connector into IOX-KEYLESS.

  • In-Vehicle Install and Functionality Test

    After completing the connections, test the functionality of the relay and IOX-KEYLESS systems by simulating the intended use of the relay.

    Ensure the vehicle cannot be started without the IOX-KEYLESS enabling mobilization. After testing is approved, securely fasten the harness and vehicle wires within dash trim, and clear of all vehicle controls.

    Part 1

    To test your installation, use an alternate set of keys to the vehicle (alternate to the key within the IOX-KEYLESS). Complete steps one to four from the table below and use the HRN-CX10S4 to disconnect from the IOX-KEYLESS.

    Complete the following to test your installation:

    1. With the relay plugged into its socket, confirm that the vehicle can start.
    2. With the vehicle running, remove the relay from its socket and confirm that the engine remains running.
    3. Turn off the engine and with the relay still removed from its socket, attempt to start to ensure the vehicle does not start.
    4. Plug the relay back into its socket and confirm that the vehicle starts.
    5. Finally Confirm you have Interfaced to TRUE IGNITION, (not to an Ignition sense line or Accessory that drops out during CRANK/START) Use a Digital VoltMeter to ensure your Ignition Interface to the vehicle is +12/24v with vehicle key in both ON/RUN and START/CRANK position. Alternatively, remove the inline fuse (see “E” of fig. 1) and set your Digital VoltMeter to DC current mode to ensure you see ~100 milliAmps (for relay coil and associated active electronic switch circuitry) when the Starter Inhibit is activated.

    This completes the local installer controlled Starter Inhibit test and confirms that the correct OEM/vehicle wires for Starter Inhibit have been selected and connected.


    In the event the test did not pass, review ALLDATA™, WireSheet™, or equivalent, then ensure that the correct wire in the vehicle is cut, to provide the Starter Inhibit functionality.

    For example, If the engine stops in step two above, it is possible that the Ignition wire was cut in error.

    With all above steps passing, perform your Install Test and enter Local Starter Inhibit test PASS in the Notes section of Ensure to take the following three pictures:

    1. The VIN number,
    2. The starter wires cut with relay contact wires soldered, and
    3. Showing these same starter wires sealed (heatshrink of tape and cable-tied).

    ! IMPORTANT: Prior to performing the next installation test steps, the GO9 must have all three LEDs on solid.

    Part 2

    A hardware validation (end to end functionality) test is to be completed by the Customer using the Geotab Keyless Mobile Application upon successful installation of Geotab Keyless Hardware. Instructions for downloading iOS and Android versions of the Keyless Mobile applications are provided in the User Guide and here:

    1. Log into the Keyless Application.
    2. Book a vehicle for a time that is in the present.
    3. Click Check In (if this fails, repeat until check in success appears on the screen).
    4. Ensure the vehicle starts.
    5. Check out and cancel your reservation.
    6. Attempt to start the vehicle and ensure that the vehicle does not start.

    The IOX-KEYLESS should not be engaging the onboard relay 1. If it does not start, please call support for troubleshooting steps.

    Finishing Up

    When the installation test is successful, properly insulate and secure using heat shrink or insulation tape and cable ties at the connection points, and protective wire loom ensuring that no colored wire is exposed.

    Use a cable tie to secure the cable run from the soldered connections to the IOX-KEYLESS every six inches (or 150 mm) to ensure the cable cannot be cut on any under-dash trim or components, and the harness and wires are kept clear of all vehicle controls.

    Frequently Asked Questions (FAQ)

    What happens if the GO device and/or IOX-KEYLESS is unplugged?

    The Start Inhibit device (relay) is Normally Closed. In the event the power/fuse to either the GO device or HRN-CX10S4 harness is disconnected/blown, or the GO device or the HRN-CX10S4 harness is unplugged, the Start Inhibit device will no longer function and the vehicle will be able to start.

    How does this functionality work with newer cars where the engine auto stops/starts at traffic lights?

    Ignition is buffered on the device to validate that the GO device detects a true ignition off, rather than an ignition off for a stop start condition. If there are vehicles where the GO is not properly detecting the ignition event, then a Support ticket/firmware investigation would be required.

    Important Safety Information and Limitations of Use

    For the latest version of the Limitations of Use, please visit:

    WARNING! The HRN-CX10S4 harness is designed and intended for use only with the GO device or Geotab-authorized accessory devices. Professional installation from a Geotab Authorized Installer is required. Read and follow the complete GO device installation instructions ( as well as these installation instructions to prevent serious personal injury or significant damage to your vehicle.

    WARNING! The HRN-CX10S4 must not be installed in such a manner where it has the potential to disable propulsion and/or prevent vehicle control while the vehicle is in motion. Please contact Geotab Support if you have any questions.

    WARNING! Do not attempt to install, configure 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! 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! If at any point after an in-vehicle device is installed, a warning lights up on the vehicle dash or the vehicle stalls or has a marked drop in performance, shut off the engine, remove the device, and contact your Partner. Continuing to operate a vehicle with these symptoms can cause loss of vehicle control, and serious injury.

    WARNING! Your 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 that can lead to a fire hazard or vehicle damage or serious injury.

    WARNING! Do not remove a device from its original vehicle, then attempt to install it in another vehicle.. Not all vehicles share compatibility, 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 and cause death or serious injury and/or vehicle damage.

    WARNING! This product does not contain any user-serviceable parts. Configuration, servicing, and repairs must only be made by an Authorized Partner or Installer. Unauthorized servicing of these products will void your product warranty.

    WARNING! Cancer and Reproductive Harm. For more information visit,

    Addendum 1: Engine Bay Interfacing Cautions and Best Practices

    ! IMPORTANT: Geotab provides limited guidance on Internal Combustion Engine vehicles with multiplexed starter circuitry that may require wire runs from under the dash into the engine bay. However, because we are not in front of the vehicles, interfacing details such as best practices and firewall pass through for each make/model/year group, must be discussed and signed off in advance by the primary on-site stakeholders; this may include the Geotab Authorized Installer's primary contact, the client's primary contact and/or fleet manager, and/or the auto-shop supervisor. Starter Inhibit wire interface/cut location. It's important to locate the correct wire to cut and interface, as there are many different makes, models and years of vehicles. Starter Inhibit wire interfacing can be under the dash or in the engine bay, example: when the dash wiring is multiplexed. ! IMPORTANT: When performed within the engine bay, this must be discussed in detail and signed off in advance by the primary on-site stakeholders. Including but not limited to the client's Fleet Manager and the shop supervisor, when soldering an uncut wire as an ignition wire, tape and cable tie to seal.

    All wire-cut interfacing must be soldered and should be sealed using heat-shrink. After cutting the correct wire, install heat shrink, then twist wires together. Using any small electronic or gas soldering tool, heat wires just enough to accept the solder flow. Let cool then apply the heat shrink, including shrinking/sealing with your heat source.

    ! IMPORTANT: Protective loom. Installing a loom is very important, as it protects your live wires from chafing that can cause severe damage to the vehicle.

    Firewall pass through/engine bay install. When running your loomed wire through the firewall, make sure there are no sharp firewall edges. To accomplish this, run your cable/loom alongside existing wiring through the firewall via the grommet/rubber/plastic seal and then cable tie, in some cases you may need to drill and provide your own round rubber grommet, CAUTION: drilling is an extreme measure, always look on opposite side for obstructions and wiring, sign on in writing by email is required in advance. Once the loom is through the firewall, make all under-dash connections and secure it with cable ties at the minimum every foot (300mm).

    Photos showing examples of firewalls pass through, prior to applying silicone. Always use an existing grommet whenever possible.

    IMPORTANT: After performing pass-through of wiring and protective loom, next step, add RTV/Silicone to all mating areas on both sides. To ensure airtight, no carbon monoxide can pass through.

    Photo showing cut and interface of OEM wire between starter relay in Fuse Panel to the starter mounted Solenoid, prior to adding loom.

    Photo showing cable/loom run. When running your loom, leave an additional loop if required, for any preventative maintenance procedure the shop may need to perform, for example, battery removal/replacement or fuse/relay cover removal, without stressing/damaging your cable run.