| Problem | R4.0 Manual Diagnosis | Solution (Page Ref) | | :--- | :--- | :--- | | | Red LED flashes once, then off: Internal fuse blown. | Check battery voltage (min 10.8V). Replace 5A fuse. Page 34. | | No audio on receive | Speaker icon is crossed out on display: Headset mode stuck. | Cyclic power with no accessory plugged in. Page 58. | | GPS not reporting | GPS icon blinks but never solid: R4.0 cold-start bug. | Drive to open area. Perform "Hot Start Reset" via Menu > Setup > Reset > GPS. Page 72. | | "Not Authorized" on PTT | Radio denies TX even with good signal. | Your authentication key expired. Contact dispatcher for OTA re-key. Page 101. |
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| Problem | Possible Cause | Solution | | :--- | :--- | :--- | | | Blown fuse or loose connection. | Check the vehicle fuse box and radio power cables. | | No audio received | Volume too low or mute enabled. | Adjust volume knob; check if headset is plugged in (diverting audio). | | Cannot transmit (No TX) | Out of coverage area. | Check signal bars on LCD. Move to a better location. | | "Service Restricted" | SIM card issue or not registered. | Check SIM card insertion; verify network subscription. | | GPS not working | GPS disabled or weak signal. | Ensure GPS is enabled in Menu > Settings > GPS. Move to open sky. | | Problem | R4
You can check your current version by navigating to Menu > Settings > Device Information . Page 34
: Instructions for Group, Private, and Phone calls.