Guide to Bringing Your TCU Back Online

Step 1: Obtain a SIM Card

You’ll need a SIM card to enable cellular connectivity for the TCU. Here’s how to proceed:

• Recommended Provider: GL-1 variant SIM card from provider Hologram.io. Resellers in EU: DigiKey, Mouser. (Sparkfun CEL-17117 is same as GL-1 SIM). Hologram offers free inbound SMS, which is critical for TCU functionality, which relies on SMS for initial configuration or diagnostics. Monthly cost of 1 dollars with data consumption billed separately.
  NOTE! Make sure you order GL-1 variant of Hologram SIM card, other variants don't work with this TCU!
• SIM Type: Ensure it’s a standard Mini SIM (2FF) or compatible with an adapter.
• Data Plan: Select a plan with at least 1-5 MB of monthly data without navigation unit, 5-20 MB of monthly data with navigation unit (TCUs typically use minimal data for telemetry, while navigation unit consumes a bit more for functions).
• Ordering: You can order sim on Hologram’s website, or use one of resellers. Resellers tend to be cheaper, although shipping costs are expensive. Reseller list will be updated once cheaper options are found. After receiving the SIM, activate it on holoram dashboard before use.
• Alternative Providers: If Hologram isn’t available, use a provider with affordable data and SMS support (e.g., AT&T, T-Mobile prepaid SIMs), but you will need a way to send SMS from the internet if you wish to use automations. 46elks, something similar or your own solution via webhook. If you intend to use it on the mobile app primarily, you can send SMS from OpenCARWINGS app automatically for each command.

Note: Test the SIM in a phone first to ensure it’s active and receives SMS/data.

Step 2: Access the TCU

The TCU is typically located behind the glovebox in many vehicles (e.g., Nissan Leaf). Follow these steps:

• Tools Needed: Phillips screwdriver, plastic trim removal tool (to avoid scratching), flashlight.
• Preparation: Turn off the vehicle and remove the key from the ignition to avoid electrical issues.
• Glovebox Removal:
  1. Open the glovebox and empty its contents.
  2. Locate and remove screws (usually 2-4) along the edges or inside the glovebox.
  3. Gently pull the glovebox forward; it may be held by clips—use the trim tool to pry it loose if needed.
  4. Disconnect any wiring (e.g., glovebox light) by pressing the connector tabs and pulling.
• Locate the TCU: Behind the glovebox, you’ll see a rectangular metal or plastic unit (about the size of a small book) with wiring harnesses and an antenna connection—this is the TCU.
• Visual Guide: Watch this YouTube video for a step-by-step demonstration:

Note: Work carefully to avoid damaging clips or wiring. Take photos of the setup before proceeding for reference.

Step 3: Replace the SIM Card

With the TCU exposed, replace the old SIM card:

• Disconnect Power: Unplug the TCU’s main harness (usually a multi-pin connector) to power it down safely.
• Open the TCU: Unscrew or unclip the TCU SIM slot cover.
• Remove Old SIM: Locate the SIM slot (a small tray or slide-down slot), and set it aside.
• Insert New SIM: Insert the new SIM card and slide slot to lock position.
• Reassemble: Close the SIM slot cover, secure screws/clips, and reconnect the harness.

Note: Handle the SIM and TCU gently to avoid bending pins or damaging components.

Step 4: Program the settings

The Access Point Name (APN) must be configured for the TCU to connect to the cellular network. Use an Android app:

• Download the App: Get the TCU Configurator app from GitHub: tcu-configurator-xx.apk.
• Install the App:
  1. Transfer the .apk file to your Android device (via USB, email, etc.).
  2. Enable “Install from Unknown Sources” in Settings > Security.
  3. Open the file and install the app.
• Connect to TCU: Power on the vehicle. Use the app to connect to the TCU via Bluetooth OBD.
• Set APN:
  1. Open the app and locate the APN settings.
  2. Enter the APN for your SIM provider (e.g., Hologram’s is “hologram”; check your provider’s website for specifics).
  3. Save and apply the settings.
• Set Server Hostname (optional):
  1. If your LEAF is EU-market model, you can skip this section if you don't want to use alternative server.
  2. In case you have US-spec car and want to use public server, you can use hostname for default server: nissan-eu-dcm-biz.viaaq.eu
  3. Enter the Server URL in TCU configurator app.
  4. Save and apply the settings.

Note: Ensure your Android device has Bluetooth enabled and the car ignition is turned on to ACC during configuration.

Note: If you have trouble reading configuration of TCU, turn off Data integrity check in TCU Configurator app.

Step 5: Complete Setup on Website

Finalize the TCU activation via a web portal:

• Identify the Service: Determine the telematics service your vehicle uses (e.g., NissanConnect for Leaf). Check your vehicle manual or service website.
• Log In/Register: Visit the service’s website, log in with your vehicle account, or create one using your VIN (Vehicle Identification Number).
• Activate TCU:
  1. Navigate to the telematics or connectivity section.
  2. Enter the new SIM’s details (e.g., phone number, ICCID from the SIM card).
  3. Follow prompts to pair the TCU with your account.
• Verify: Do a data refresh to confirm the TCU is online.