1. Introduction
This manual provides detailed instructions for the installation, operation, and maintenance of your JVC KW-R400 Double DIN Stereo System. Please read this manual thoroughly before using the unit to ensure proper operation and to prevent damage.
Key Features
- Front USB and AUX Input for external device connectivity.
- MOS-FET Power Amplifier with 4 x 50 Watts output for clear audio.
- RDS Radio Tuner for enhanced radio reception and information.
- Compatibility with MP3/WMA audio files, including ID3/WMA tags.
- Subwoofer control and 4.8V line output for expanded audio systems.
- Auto dimmer and separated brightness control for display customization.

Figure 1: Front view of the JVC KW-R400 Double DIN Stereo System, showing the display, control knob, and front panel inputs.

Figure 2: Angled view of the JVC KW-R400, highlighting the illuminated controls and overall design.
2. Setup and Installation
Proper installation is crucial for optimal performance and safety. It is recommended to have this unit installed by a qualified professional. Incorrect installation can lead to malfunction or damage to the unit or vehicle.
2.1 Wiring Connections
Ensure all wiring connections are secure and correctly matched to your vehicle's electrical system. Refer to your vehicle's service manual for specific wiring diagrams. The unit typically uses standard ISO connectors, but an adapter may be required for certain vehicle models.
- Power Connection: Connect the yellow wire to the constant 12V supply, the red wire to the accessory 12V supply, and the black wire to ground.
- Speaker Connections: Connect the speaker wires to the corresponding positive (+) and negative (-) terminals of your vehicle's speakers. Ensure correct polarity.
- Antenna Connection: Connect the vehicle's antenna cable to the antenna input on the rear of the unit.
- External Amplifier/Subwoofer: Use the RCA pre-output terminals for connecting external amplifiers or subwoofers.
2.2 Mounting the Unit
Mount the unit securely in the vehicle's double DIN opening using the supplied mounting hardware. Ensure adequate ventilation around the unit to prevent overheating.
3. Operating Instructions
3.1 Basic Operation
- Power On/Off: Press the SOURCE button to turn the unit on. Press and hold the SOURCE button to turn it off.
- Volume Control: Rotate the VOLUME/ENTER knob to adjust the volume level.
- Source Selection: Press the SOURCE button repeatedly to cycle through available sources (Tuner, CD, USB, AUX).
- Menu Access: Press the MENU button to access system settings and audio adjustments.
3.2 USB and AUX Input
The KW-R400 features a front USB port and front/rear AUX inputs for connecting external audio devices.
- USB Playback: Connect a USB mass storage device (e.g., USB flash drive) to the front USB port. The unit will automatically switch to USB source and begin playback of compatible MP3/WMA files.
- AUX Input: Connect an external audio player (e.g., smartphone, portable music player) to the front or rear AUX input using a 3.5mm stereo mini-jack cable. Select the AUX source to listen to audio from the connected device.
3.3 Radio Tuner Operation
The built-in HS-IVi tuner provides access to FM/AM radio broadcasts.
- Band Selection: Press the BAND button to switch between FM and AM bands.
- Manual Tuning: Use the SEEK buttons (left/right arrows) to manually tune to a desired frequency.
- Seek Tuning: Press and hold the SEEK buttons to automatically search for the next strong station.
- Preset Stations: Store your favorite stations using the numbered preset buttons (1-6). To store, tune to the desired station, then press and hold a preset button until you hear a beep.
- RDS Functions: The RDS (Radio Data System) feature provides additional information such as station name and program type.
3.4 Audio Settings
Adjust audio settings to customize your listening experience.
- Equalizer (EQ): Press the EQ button to access the 3-band parametric iEQ. Use the VOLUME/ENTER knob and arrow buttons to adjust frequency bands and levels.
- Subwoofer Control: If a subwoofer is connected, access the subwoofer control settings through the MENU to adjust output level and crossover frequency.
- Loudness: Enable or disable the Loudness feature for enhanced bass and treble at low volumes.
4. Maintenance
Regular maintenance ensures the longevity and optimal performance of your stereo system.
- Cleaning the Unit: Wipe the front panel with a soft, dry cloth. For stubborn dirt, dampen the cloth with a small amount of water. Avoid using abrasive cleaners, solvents, or alcohol, as these can damage the finish.
- USB Port: Keep the USB port free from dust and debris. Avoid inserting foreign objects.
- CD Slot: Do not insert anything other than standard audio CDs into the CD slot. Avoid using scratched or damaged discs.
5. Troubleshooting
If you encounter issues with your JVC KW-R400, refer to the table below for common problems and their solutions.
| Problem | Possible Cause | Solution |
|---|---|---|
| No power | Incorrect wiring; Blown fuse; Vehicle battery low. | Check power connections (yellow, red, black wires). Replace fuse if blown. Check vehicle battery. |
| No sound | Volume too low; Mute function active; Incorrect speaker wiring; Amplifier not connected/powered. | Increase volume. Deactivate mute. Check speaker connections. Ensure external amplifier is powered on. |
| USB device not recognized | Incompatible format; Damaged USB device; Loose connection. | Ensure files are MP3/WMA. Try a different USB device. Reconnect USB device firmly. |
| Poor radio reception | Antenna not connected; Weak signal area; Damaged antenna. | Check antenna connection. Try tuning to a stronger station. Inspect antenna for damage. |
| Buttons not responding | System freeze; Moisture/debris in buttons. | Perform a soft reset (consult JVC support if needed). Clean buttons carefully. |
6. Specifications
Technical specifications for the JVC KW-R400 Double DIN Stereo System.
| Feature | Detail |
|---|---|
| Model Number | KW-R400 |
| Manufacturer | JVC |
| Product Dimensions (LxWxH) | 15.01 x 5.99 x 10.01 cm (5.91 x 2.36 x 3.94 inches) |
| Item Weight | 998 g (2.2 lbs) |
| Amplifier Type | MOS-FET |
| Output Power | 4 x 50 Watts (Max) |
| Audio Wattage | 200 Watts (Total) |
| Connectivity Technology | Auxiliary |
| Connector Type | 3.5mm Jack, USB |
| Hardware Interface | USB |
| Compatible Devices | Speakers |
| Media Format | MP3 Audio, WMA |
| Special Features | RDS, Subwoofer Control, 3-band Parametric iEQ, Auto Dimmer |
| Voltage | 2.5 Volts (Line Output) |
| Audio Output Mode | Stereo |
| Surround Sound Channel Configuration | 4.0 |
7. Warranty and Support
For warranty information, please refer to the warranty card included with your product or visit the official JVC website. For technical support, service, or inquiries, please contact JVC customer service through their official channels. Keep your purchase receipt as proof of purchase for warranty claims.
JVC Official Website: www.jvc.com





