GMOS-04 - Car Kit Metra - Free user manual and instructions

Product Type	GM OnStar Class II Data Bus Interface
Brand	Metra
Model	GMOS-04
Compatible Vehicles	2000-2009 GM models (Buick, Cadillac, Chevrolet, GMC, Hummer, Isuzu, Oldsmobile, Pontiac, Saab, Saturn, etc.)
Retains OnStar	Yes
Retains Warning Chimes	Yes (adjustable via potentiometer)
Retains RAP (Retained Accessory Power)	Yes
Outputs Provided	12V switched, mute, parking brake, VSS (speed sense), reverse
Amplified System Support	Designed for factory amplified systems including Bose
Harnesses Included	14-pin harness with RCA, 16-pin to 24-pin and 12-pin harness
Audio Input	RCA (front/rear left/right)
Audio Level Adjustment	Potentiometer for input level (to prevent distortion)
Chime Level Adjustment	Potentiometer on module side
OnStar Volume Adjustment	Via tapping black/yellow wire to ground (4 levels)
Installation Difficulty	Moderate (requires cutting/taping wires, professional installation recommended)
Tools Required	Cutting tool, tape, crimping tool, connectors (butt-connectors, bell caps)
Power Supply	12V vehicle battery (constant and switched)
Dimensions (approx)	4 x 2 x 1 inches
Weight (approx)	0.3 lb (150 g)
Safety Warnings	Disconnect negative battery terminal; read instructions; consult technician if unsure

Frequently Asked Questions - GMOS-04 Metra

Which vehicles is the Metra GMOS-04 compatible with?

The GMOS-04 is compatible with a wide range of 2000-2009 GM vehicles, including Buick Allure, Cadillac Escalade, Chevrolet Silverado, GMC Yukon, Hummer H2, Pontiac Grand Prix, and many others. See the full applications list inside the manual.

Does the GMOS-04 retain the factory OnStar system?

Yes, the GMOS-04 is designed to retain OnStar functionality. When the OnStar button is pressed, the aftermarket radio will mute and OnStar audio plays through the left front speaker.

How do I adjust the OnStar volume level?

Locate the black/yellow wire that was cut on the 16-pin harness (the isolated one). While OnStar is speaking, tap that wire to ground. Repeat to cycle through 4 volume levels. Once set, it stays until tapped again. Optionally, install a momentary switch.

How do I adjust the chime volume if it's too loud or too soft?

Turn ignition off, disconnect harnesses from the GMOS-04 module. Locate the chime potentiometer on the left side of the module. Use a small flathead screwdriver: turn clockwise to decrease chime level, counterclockwise to increase.

How do I fix distorted audio output?

If audio is distorted (typically with high pre-out voltage >2V), turn ignition off, disconnect harnesses. Locate the audio level potentiometer next to the 14-pin connector. Turn it counterclockwise to lower the input level to the factory amplifier.

Does the GMOS-04 retain the RAP (Retained Accessory Power) feature?

Yes, the GMOS-04 is designed to retain the RAP feature, so the radio stays on until a door is opened after turning off the ignition.

Is any special installation required for the 2005-2009 Corvette?

Yes. For the 2005-2009 Corvette, a relay is required. Cut the blue/white wire between the 16-way Molex and 24-way gray connector, then wire the relay as shown in the manual: pin 85 to the 16-way side, pin 30 to the 24-way side, pin 86 to ground, pin 87 to fused 12V constant.

What is the purpose of the blue/white wire on the 14-pin harness?

The blue/white wire is the amplified turn-on output. Connect it to the radio's AMP turn-on wire to power the factory amplifier when the radio is on.

Can I install the GMOS-04 myself?

The installation requires cutting and connecting wires, and knowledge of vehicle electronics. Metra recommends a MECP certified technician. If you are unsure, consult a professional to avoid damage to safety systems.

What extra parts do I need if my aftermarket radio lacks RCA outputs?

If your radio does not have RCA outputs, you will need a line output converter, such as the Metra part #ALO-648 (sold separately), to connect to the GMOS-04's RCA inputs.

USER MANUAL GMOS-04 Metra

GM ONSTAR CLASS II DATA BUS INTERFACE

GMOS-04 Installation Instructions

* READ IMPORTANT WARNING ON PAGE 2 BEFORE ATTEMPTING ANY INSTALLATION

THE GMOS-04 IS DESIGNED TO BE USED WITH VEHICLES THAT HAVE A FACTORY AMPLIFIED SYSTEM INCLUDING THE BOSE AUDIO SYSTEMS. BESIDES RETAINING THE ONSTAR SYSTEM, THE GMOS-04 WILL ALSO RETAIN THE WARNING CHIMES THAT WILL BE LOST WHEN THE FACTORY RADIO IS REMOVED. THE GMOS-04 WILL ALSO PROVIDE A 12 VOLT SWITCHED WIRE FOR PROPER RADIO OPERATION. THE GMOS-04 NOW PROVIDES MUTE, PARKING BRAKE, VSS OR SPEED SENSE, AND A REVERSE OUTPUT TO MAKE INSTALLING AN AFTERMARKET NAVIGATIONAL RADIO SIMPLER AND LESS TIME CONSUMING.

• SEE APPLICATIONS LIST INSIDE •

TOOLS REQUIRED FOR INSTALLATION

• Cutting Tool
• Tape
• Crimping Tool
• Connectors (ie: butt-connectors, bell caps, etc.)

APPLICATIONS

BUICK

ALLURE 2005-09

CENTURY 2004-05

LACROSSE 2005-09

RAINIER 2004-07

RENDEZVOUS 2002-07

TERRAZA 2005-08

CADILLAC

ESCALADE 2003-06

ESCALADE EXT 2003-06

CHEVROLET

AVALANCHE 2003-06

CAVALIER 2000-05

CORVETTE 2005-09*

*See note for Corvette in

"CONNECTIONS TO BE MADE ON

THE 24 PIN GRAY HARNESS"

EXPRESS 2003-07

IMPALA 2000-05

MALIBU 2002-03

MALIBU CLASSIC 2004

MONTE CARLO 2000-05

SILVERADO 2003-06

SILVERADO CLASSIC 2007

SUBURBAN 2003-06

TAHOE 2003-06

TRAILBLAZER 2002-09

UPLANDER 2005-08

VENTURE 2000-05

We recommend MECP certified technicians

GMC

ENVOY 2002-09

SAVANA 2003-07

SIERRA 2003-06

SIERRA CLASSIC 2007

YUKON/XL/DENALI 2003-06

HUMMER

H2 2003-07

H3 2006-09

ISUZU

ASCENDER 2003-08

I SERIES 2006-08

OLDSMOBILE

ALERO 2001-04

BRAVADA 2002-04

INTRIGUE 2002

SILHOUETTE 2000-04

PONTIAC

AZTEC 2001-05

GRAND AM 2001-05

GRAND PRIX 2004-08

MONTANA 2000-2005

SUNFIRE 2000-05

SAAB

9-7x 2005-09

SATURN

RELAY 2005-07

We recommend MESA certified technicians

INTERFACE COMPONENTS

• GMOS-04 Data Interface
• 14 pin harness with RCA'S
- 16 pin harness to 24 pin GM harness and 12 pin Onstar harness

\* IMPORTANT WARNING

THIS PRODUCT INCLUDES INSTRUCTIONS FOR INSTALLATION WHICH MUST BE CAREFULLY FOLLOWED. THE INSTRUCTIONS ARE WORDED IN SUCH A MANNER TO ASSUME THAT THE INSTALLER IS CAPABLE OF COMPLETING THESE TYPE OF ELECTRONIC INSTALLATIONS. IF YOU ARE UNCLEAR AS TO WHAT YOU ARE INSTRUCTED TO DO OR BELIEVE THAT YOU DO NOT UNDERSTAND THE INSTRUCTIONS SO AS TO PROPERLY AND SAFELY COMPLETE THE INSTALLATION YOU SHOULD CONSULT A TECHNICIAN WHO DOES HAVE THIS KNOWLEDGE AND UNDERSTANDING. FAILURE TO FOLLOW THESE INSTRUCTIONS CAREFULLY AND TO INSTALL THE INTERFACE AS DESCRIBED COULD CAUSE HARM TO THE VEHICLE OR TO SAFETY SYSTEMS ON THE VEHICLE. INTERFERENCE WITH CERTAIN SAFETY SYSTEMS COULD CAUSE HARM TO PERSONS AS WELL. IF YOU HAVE ANY QUESTIONS IN THIS REGARD PLEASE CALL THE HELP LINE OR THE METRA AT 1-800-221-0932 FOR ASSISTANCE.

WIRING UP THE GMOS-04

* Important: Before beginning any of the following, disconnect the negative battery terminal to prevent accidental short circuit.
**Note: The ignition power source of most GM vehicles keep the radio on until one of the doors is opened. This is called the R.A.P. (retained accessory power).

The GMOS-04 is designed to retain this feature.

CONNECTIONS TO BE MADE ON THE 24 PIN

GRAY HARNESS:

1. Connect the yellow wire to the radio's 12V battery or memory wire.
2. Connect the black wire to the radio's ground wire.
3. Connect the orange wire to the radio's illumination wire. If the wire is not present, tape up wire.
4. Connect the orange/white wire to the radio's dimmer wire. If the wire is not present, tape up wire.

See page 3 for "2005-2009 CORVETTE ONLY" special instructions.

Continued from page 2

FOR 2005-2009 CORVETTE ONLY

1. A Relay is needed in the 2005-2009 Corvette. You will need to cut the blue/white wire in half between the 16 way Molex and 24 way gray connector.

2. Connect the blue/white wire coming from the 16 way Molex to pin 85 of the Relay.

3. Connect the blue/white wire coming from the 24 way connector to pin 30 of the Relay.
4. Connect pin 86 of the Relay to Ground.
5. Connect pin 87 of the relay to fused 12 volt constant wire. Using tape or a wire tie securely the Relay from moving around in the dash.

graph TD
    A["To RADI"] --> B["12v remote from GMOS-04 Blue/white"]
    B --> C["SPDT relay"]
    C --> D["+12v Battery Fused 5A"]
    D --> E["To vehicle"]
    style A fill:#f9f,stroke:#333
    style B fill:#ccf,stroke:#333
    style C fill:#cfc,stroke:#333
    style D fill:#fcc,stroke:#333

- When completed, plug the 16 pin harness into the GMOS-04.

CONNECTIONS TO BE MADE ON THE 14 PIN

HARNESS

1. Connect the blue/white wire to the radio's AMP turn-on wire.
2. Connect the red wire to the radio's Igniton or accessory wire.
3. Connect the RCA cables to the radio's RCA outputs. If no RCA outputs are available, use the Metra line output converter part #ALO-648 (SOLD SEPARATELY).
4. The white RCA goes to the left front RCA output of the radio.
5. The gray RCA goes to the front right RCA output of the radio.
6. The green RCA goes to the left rear RCA output of the radio.
7. The purple RCA goes to the right rear RCA output of the radio.

The following wires on the 14 pin harness are for the aftermarket radios that have navigation built in:

1. Connect the Brown wire to the mute wire of the aftermarket radio.
2. Connect the Green wire to the parking brake wire of the aftermarket radio.
3. Connect the Blue/Pink wire to the VSS or speed sense wire of the aftermarket radio.
4. Connect the Green/Purple wire to the reverse wire of the aftermarket radio.

- When completed, plug the 14 pin harness into the GMOS-04.

INSTALLING THE GMOS-04

1. With all connections completed to the aftermarket radio, plug the 24 pin and the 12 pin connectors into the vehicles corresponding wiring harnesses.
2. Reconnect the negative battery terminal.
3. Cycle the key by turning the ignition on then back off, then back on again to test the radio.

TESTING THE GMOS-04

1. Turn the ignition on then the radio to verify the radio works. Check balance and fader controls for proper operation. If controls are backwards, check to see if the RCA's are in the correct location.
2. Push the Onstar button to verify Onstar is working. the radio will shut off and Onstar will be heard through the left front speaker. Turn off Onstar and the radio will turn back on.

ONSTAR LEVEL ADJUSTMENT

To adjust the Onstar volume level find the Black/yellow wire that you cut on the 16 pin harness, you will use the Black/yellow wire that is by itself, with no other wire with it. Push the blue Onstar button, while the voice is speaking tap the Black/yellow wire to ground. There are 4 volume settings for Onstar; once the 4th setting is reached and the Black/yellow wire is tapped to ground it will automatically go back to the first volume setting. Once the volume is set it will stay at that volume until the Black/yellow wire is tapped to ground again. This can be set during installation and then left alone. If user adjustment is desired, a momentary contact switch (sold separately) can be added. Connect one terminal from the switch to ground and the other terminal to the Black/yellow wire. The volume will change one level every time the switch is pressed.

TROUBLESHOOTING:

Chime Too Loud/Soft:

There are some instances where the chime is too loud or too soft.

To resolve this follow these steps:

1. Make sure the ignition is turned to the "off" position.
2. Disconnect the 14 pin and 16 pin wire harnesses from the GMOS-04.
3. Locate the potentiometer on the left side of the module, this is the Chime potentiometer.
4. Taking a small flat headed screwdriver, turn the potentiometer clockwise to decrease the chime level; turning the potentiometer counterclockwise will increase the chime level.

Distorted Audio Output:

When using the GMOS-04 with a radio that has a high pre-out voltage, usually greater than 2 volts, the audio signal may become distorted.

To resolve this follow these steps:

1. Make sure the ignition is turned to the "off" position.
2. Disconnect the 14 pin and 16 pin wire harnesses from the GMOS-04.
3. Locate the potentiometer next to the 14 pin connector located at the end of the GMOS-04.
4. Taking a small flat headed screwdriver, turn the potentiometer counter clockwise to lower the input level going to the factory amplifier.

GMOS-04 INSTRUCTIONS

GM ONSTAR CLASS II DATA BUS INTERFACE

GMOS-04

*See note for Corvette in

"CONNECTIONS TO BE MADE ON

THE 24 PIN GRAY HARNESS"

EXPRESS 2003-07

IMPALA 2000-05

MALIBU 2002-03

MALIBU CLASSIC 2004

MONTE CARLO 2000-05

SILVERADO 2003-06

SILVERADO CLASSIC 2007

SUBURBAN 2003-06

TAHOE 2003-06

TRAILBLAZER 2002-09

UPLANDER 2005-08

VENTURE 2000-05

Salida de audio distorsionada: