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Geotab Keyless Starter Inhibit Overview and Installation for the HRN-CX10S4 Harness
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Learn more about the Geotab Keyless Starter Inhibit feature, including how to install it using the HRN-CX10S4 harness. Browse frequently asked questions about set up and installation, and review important safety information.
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.
✱ 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:
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.
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.
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.
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.
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.
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.
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.
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.
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
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
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
−40 to +85 °C
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.
The following table outlines the schematic for this example:
In-Vehicle With Photos Step
HRN-CX10S4 10 Pin Connector connecting to IOX-KEYLESS
(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
✱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.
This is the blue/white wire in this example.
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.
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.
! IMPORTANT: Verify there is no wiring or object behind the location of the ring terminal prior to drilling.
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.
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:
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 www.InstallMyGPS.com. Ensure to take the following three pictures:
! IMPORTANT: Prior to performing the next installation test steps, the GO9 must have all three LEDs on solid.
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:
The IOX-KEYLESS should not be engaging the onboard relay 1. If it does not start, please call support for troubleshooting steps.
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.
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.
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.
For the latest version of the Limitations of Use, please visit: goo.gl/k6Fp0w.
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 (goo.gl/rkLRiA) 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, www.P65Warnings.ca.gov.
! 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.