Metra GMOS-LAN-04 Interface User Manual

1. Product Overview

The Metra GMOS-LAN-04 is an amplified interface harness designed to facilitate the replacement of the original equipment manufacturer (OEM) radio with an aftermarket receiver in specific 2006-2008 GM vehicles that utilize the GMLAN Data Bus system. This interface ensures the retention of critical factory features, including the OnStar system, safety and door chimes, and Retained Accessory Power (RAP).

Image of the Metra GMOS-LAN-04 interface module, showing its compact design and wiring harness connections.

2. Package Contents

Verify that all items are present in the package before beginning installation:

• Metra GMOS-LAN-04 Interface Module
• 16-pin to 30-pin GM Harness
• Instruction Manual (this document)

3. Compatibility

The GMOS-LAN-04 interface is compatible with the following vehicles:

• 2006-2008 GM Vehicles equipped with the GMLAN Data Bus system.
• Specifically designed for amplified systems in 2006-2007 Chevrolet, Pontiac, and Saturn models.

Please consult a vehicle-specific application guide for exact model and trim compatibility.

4. Features

The Metra GMOS-LAN-04 interface provides the following functionalities:

• Allows for the replacement of the OEM radio with an aftermarket receiver.
• Retains full functionality of the OnStar system with adjustable volume output.
• Retains safety and door chimes with adjustable level output.
• Maintains the Retained Accessory Power (RAP) convenience feature.
• Provides a 16-pin to 30-pin GM harness for direct connection.

5. Installation (Setup)

Professional installation is recommended. Always disconnect the vehicle's battery before beginning any electrical work. Refer to your vehicle's service manual for specific radio removal procedures.

1. Disconnect Battery: Disconnect the negative terminal of the vehicle's battery to prevent electrical shorts.
2. Remove OEM Radio: Carefully remove the factory radio from the dashboard. This typically involves removing trim panels and unscrewing the radio unit.
3. Connect Interface Harness: Connect the Metra GMOS-LAN-04 harness to the factory wiring harness that was previously connected to the OEM radio. Ensure all connections are secure.
4. Wire Aftermarket Radio: Connect the aftermarket radio's wiring harness to the corresponding wires on the GMOS-LAN-04 interface harness. Follow the wiring color codes provided with your aftermarket radio and the GMOS-LAN-04 instructions.
5. Adjust Settings: If applicable, adjust the volume output for OnStar and chimes using the controls on the GMOS-LAN-04 module as per its specific instructions.
6. Test Connections: Before fully reassembling the dashboard, reconnect the vehicle's battery and test the aftermarket radio, OnStar, chimes, and RAP functionality.
7. Secure and Reassemble: Once all functions are verified, secure the GMOS-LAN-04 module and wiring, then reassemble the dashboard and trim panels.

6. Operation

Once installed, the Metra GMOS-LAN-04 operates automatically to integrate your aftermarket radio with the vehicle's data system. The interface ensures that:

• OnStar: The OnStar system will function as it did with the factory radio. Its audio output can be adjusted via the interface module.
• Chimes: All factory safety and warning chimes (e.g., seatbelt, door ajar) will be retained and audible through the vehicle's speakers. The chime volume can be adjusted.
• Retained Accessory Power (RAP): The radio will continue to operate for a short period after the ignition is turned off, until a door is opened, mimicking the factory behavior.

No additional user interaction is typically required for the interface itself after initial setup.

7. Troubleshooting

If you encounter issues after installation, consider the following troubleshooting steps:

• No Power to Radio: Verify all wiring connections, especially the constant and switched 12V power wires. Check vehicle fuses.
• No Audio: Ensure speaker wires are correctly connected and not shorted. Check the amplifier turn-on lead if applicable.
• No Chimes/OnStar: Confirm the interface module is receiving power and data. Recheck connections to the factory harness. Adjust chime/OnStar volume settings on the interface.
• Mute Wire Issue: Some users have reported issues with the mute wire causing unintended muting at certain volumes. If experiencing this, try disconnecting the mute wire from the aftermarket radio's harness. This may resolve the issue without affecting other functions.
• Intermittent Functionality: Check for loose connections or damaged wiring. Ensure the interface module is securely mounted and not subject to excessive vibration.

If problems persist, contact Metra technical support or consult a qualified car audio installer.

8. Specifications

9. Warranty and Support

Metra products are designed for reliability and performance. This product is covered by a manufacturer's warranty against defects in materials and workmanship. For specific warranty terms and conditions, please refer to the documentation included with your purchase or visit the official Metra Electronics website.

For technical assistance, installation questions, or troubleshooting support, please contact Metra Electronics customer service. Contact information can typically be found on the manufacturer's website or in the product packaging.