PAC OS-2X Radio Replacement Interface with OnStar Retention User Manual for Select GM Class II Vehicles

1. Introduction

The PAC OS-2X Radio Replacement Interface is designed to allow the installation of an aftermarket radio into select General Motors (GM) Class II vehicles while retaining essential factory features. This interface ensures the continued functionality of OnStar, warning chimes, and other vehicle-specific features that would otherwise be lost when replacing the factory radio.

This manual provides detailed instructions for the proper installation, operation, and maintenance of your PAC OS-2X interface. Please read all instructions thoroughly before beginning installation.

PAC OS-2X Radio Replacement Interface module and wiring harness

Figure 1: PAC OS-2X Radio Replacement Interface module and associated wiring harness. This image shows the main components included in the package, highlighting the interface module and the various connectors for vehicle and aftermarket radio integration.

2. Safety Information

Always disconnect the vehicle's negative battery terminal before beginning any electrical installation to prevent short circuits and damage.
Ensure all connections are secure and properly insulated to prevent electrical shorts.
Refer to your vehicle's service manual for specific wiring diagrams and disassembly instructions.
If you are unsure about any part of the installation process, consult a qualified car audio technician.
Do not modify the interface module or wiring harness. Unauthorized modifications can void the warranty and cause damage.
Keep the interface module away from moisture and extreme temperatures.

3. Package Contents

Verify that all items are present before proceeding with the installation:

PAC OS-2X Interface Module
Vehicle Specific Wiring Harness
Aftermarket Radio Connection Harness
User Manual (this document)

4. Setup and Pre-Installation

Read the Manual: Thoroughly read this instruction manual and your aftermarket radio's manual before starting.
Gather Tools: Collect necessary tools such as wire strippers, crimpers, electrical tape, multimeter, and panel removal tools.
Disconnect Battery: Disconnect the negative terminal of the vehicle's battery.
Remove Factory Radio: Carefully remove the factory radio from the dashboard. Refer to your vehicle's service manual for specific instructions.
Identify Vehicle Wiring: Familiarize yourself with the vehicle's factory wiring harness.

5. Installation Instructions

Follow these steps carefully to install the PAC OS-2X interface:

Connect Aftermarket Radio Harness: Connect the wires from the aftermarket radio's harness to the corresponding wires on the PAC Aftermarket Radio Connection Harness. Match wire colors and functions (e.g., constant 12V, accessory 12V, ground, speaker wires). Solder and heat shrink, or use high-quality crimp connectors for secure connections.
Connect Vehicle Specific Harness: Plug the PAC Vehicle Specific Wiring Harness into the factory radio harness connectors in the vehicle's dashboard.
Connect Interface Module: Plug the Aftermarket Radio Connection Harness and the Vehicle Specific Wiring Harness into the PAC OS-2X Interface Module. Ensure all connectors are fully seated.
Connect Antenna Adapter (if required): If your aftermarket radio requires an antenna adapter, connect it now.
Connect Steering Wheel Control (SWC) (if applicable): If your aftermarket radio supports steering wheel controls and you wish to retain them, connect the SWC output wire from the PAC module to the SWC input of your aftermarket radio. Refer to your radio's manual for specific SWC wiring.
Test Functionality: Before reassembling the dashboard, temporarily reconnect the vehicle's negative battery terminal. Turn on the ignition and test the aftermarket radio's basic functions (power, sound, fader/balance). Verify that OnStar functionality and all warning chimes are working correctly.
Secure Components: Once all functions are verified, disconnect the battery again. Secure the PAC OS-2X module and all wiring harnesses behind the dashboard, ensuring they do not interfere with any moving parts or pinch points.
Reassemble Dashboard: Reinstall the aftermarket radio and reassemble the dashboard components.
Final Battery Connection: Reconnect the negative battery terminal.

6. Operation

The PAC OS-2X interface operates automatically once installed. Its primary function is to translate vehicle data signals for the aftermarket radio and maintain factory features.

6.1 OnStar Retention

The interface retains full OnStar functionality. When an OnStar call is initiated or received, the audio will be routed through the vehicle's speakers, and the aftermarket radio will mute or switch to the OnStar audio source, depending on the radio's capabilities.

6.2 Warning Chimes

All factory warning chimes (e.g., door ajar, seatbelt, key in ignition) are retained and will sound through the vehicle's speakers as they did with the factory radio.

6.3 Steering Wheel Controls (Optional)

If connected and configured, the interface allows the factory steering wheel audio controls to operate the aftermarket radio. Refer to your aftermarket radio's manual for programming instructions if necessary.

7. Maintenance

The PAC OS-2X interface is designed for maintenance-free operation. No user-serviceable parts are inside the module.

Ensure all wiring connections remain secure. Loose connections can lead to intermittent functionality.
Keep the area around the interface module free from excessive dust or moisture.
Do not attempt to open or repair the module.

8. Troubleshooting

If you experience issues with your PAC OS-2X interface, refer to the following table:

Problem	Possible Cause	Solution
Aftermarket radio has no power.	Loose power connection. Blown fuse in vehicle or radio. Incorrect wiring of constant or accessory power.	Check all power and ground connections. Inspect vehicle and radio fuses. Verify wiring against diagrams.
No sound from aftermarket radio.	Loose speaker connections. Aftermarket radio not properly configured. Vehicle amplifier not turning on (if applicable).	Check all speaker wire connections. Ensure radio's fader/balance is centered. Verify amplifier turn-on wire connection.
OnStar not working or no audio.	Interface module not receiving power. Incorrect connection to OnStar audio input (if applicable).	Verify power to the PAC module. Ensure OnStar audio connections are correct.
Warning chimes are missing or incorrect.	Interface module not receiving proper data. Speaker for chimes not connected.	Check all connections to the PAC module and vehicle harness. Ensure the chime speaker (if separate) is connected.
Steering Wheel Controls not functioning.	SWC wire not connected or connected incorrectly. Aftermarket radio requires programming for SWC.	Verify SWC wire connection between PAC module and radio. Refer to your aftermarket radio's manual for SWC programming.

9. Specifications

Feature	Detail
Model Number	OS-2X (Item model number: OS2X-SL)
Brand	PAC
Compatibility	Select GM Class II Vehicles
Retained Features	OnStar, Warning Chimes, Retained Accessory Power (RAP), Steering Wheel Controls (with compatible radio)
Material	Copper, Polyvinyl Chloride (PVC)
Item Dimensions (L x W x H)	9 x 9 x 2 inches
Item Weight	0.96 Pounds (approx. 15.4 ounces)
Connector Type	OEM/Deutsch DT
UPC	609098814478, 606523105729

10. Warranty and Support

10.1 Warranty Information

The PAC OS-2X interface comes with a 1 Year Manufacturer Warranty from the date of purchase. This warranty covers defects in materials and workmanship under normal use. It does not cover damage resulting from improper installation, accident, misuse, abuse, neglect, or unauthorized modification.

For warranty claims, please retain your proof of purchase and contact PAC customer support.

10.2 Technical Support

If you require technical assistance or have questions regarding the installation or operation of your PAC OS-2X interface, please contact PAC technical support. Before contacting support, please ensure you have read this manual thoroughly and performed basic troubleshooting steps.

Contact information for PAC can typically be found on their official website or on the product packaging.