PAC Audio GM1A-RT User Manual
GM1A-RT
Radio Replacement Interface with
Telematics Retention
for select General Motors Vehicles
with Class II Data-Bus
© 2018 AAMP Global. All rights reserved. PAC is a Power Brand of AAMP Global.
PAC-audio.com
Rev: V6
Date: 092718
Introduction and Features
The GM1A-RT interface allows the replacement of a factory radio in select General Motors vehicles with the Class II Data-Bus.
Using this interface will retain factory features such as OnStar, warning chimes and the factory Bose amplier when the original
radio is removed. The GM1A-RT provides data bus driven outputs such as retained accessory power (RAP), vehicle speed signal
(VSS), illumination, reverse trigger and parking brake. The GM1A-RT also provides an SWI Direct output for adding an optional
PAC Steering Wheel Control (SWC) retention interface (SWI-RC or SWI-CP2). Rear Seat Controls (RSC) if equipped will also
be retained with the SWI interface. You can also add multiple camera inputs to your aftermarket radio with Data-Bus controlled
automatic activation (front camera only) by connecting a VS41 into the expansion port on the GM1A-RT.
Important Notes
1. The included chime speaker should be used when: The vehicle has a standard Bose system (UQ7), the vehicle does not have
a factory amplier at all, or if you are connecting an aftermarket amplier to the cabin speakers.
2. The Programming Button and Adjustment Dial on the side of the interface have multiple functions. Please see Page 3 for
more details.
3. Compatible in both Premium Bose (Y91 / UQA) and Standard Bose systems.
4. Real time speaker fading on Premium factory amplied systems (UQA / Y91) is only supported with the “amplied output”
connection of the GM1A-RT.
5. When using real time speaker fading (Premium Bose only), if the fader setting is biased more to the front or rear, as the radio
turns on the sound may begin at the default setting and then quickly transition to your custom setting.
6. Aftermarket radio features such as High Pass Filters (crossovers), DSP or “Network Mode” will interfere with proper fader
function (Premium Bose Only). In order for the GM1A-RT’s fader function to work, the audio from the aftermarket radio’s
output must match so it can compare the front and rear audio levels and determine the proper fader setting for the factory
amplier.
7. When used in conjunction with the add on camera controller (VS41) the GM1A-RT will only provide Data-Bus controlled
automatic activation for the front camera. Please refer to the vehicle specic VS41 instructions for more detail.
Module Layout
Expansion Port
Adjustment Dial
Programming Button
USB PortInterface Connector 4
Non-Amplied
Audio Output
Amplied
Audio Output
LED 1
LED 2
Interface Connector 1
Interface Connector 2
Interface Connector 3
Page 1
GM1A-RT
Radio Replacement Interface with
Telematics Retention
for select General Motors Vehicles
with Class II Data-Bus
© 2018 AAMP Global. All rights reserved. PAC is a Power Brand of AAMP Global.
PAC-audio.com
Rev: V6
Date: 092718
Installation Steps
1. Wire your aftermarket radio to the GM1A-RT’s harness according to the wiring connections chart below.
2. Plug Interface Connectors 1 and 2 into the appropriate port on the GM1A-RT interface (using the illustration on page 1 or the
label on the bottom of the interface).
3. The Brown mute loop in Interface Connector 4 (if not cut) will turn the GM1A’s accessory output off when any OnStar
function is active. If the aftermarket radio has a mute input, cut this loop and connect the Brown wire in pin 23 to it.
4. The Connector 3 connection will be dependent upon whether or not the vehicle has a factory amplied system. Plug this
connector into the appropriate port on the GM1A-RT (using the illustration on page 1 or the label on the bottom of the
interface).
5. If the aftermarket radio is equipped with an auxiliary input and you wish to retain the factory RSE audio, plug the RCA
connectors from the secondary harness into the radios auxiliary input.
6. If you are also installing an optional SWC interface with the GM1A-RT, connect the SWI Direct Connector to the SWC
interface.
7. Remove the factory radio and plug in the GM1A-RT’s Vehicle Connector 1 and Vehicle
Connector 2 into the factory vehicle harness.
8. If necessary, program the SWC interface.
9. If you are connecting an aftermarket amplier to the cabin speakers, connect the
chime speaker to the chime plug coming out of Interface Connector 4 and install
the chime speaker in a place free of obstructions, where it can be easily heard
(usually low in the dash facing downward).
Interface Connector 1
(3-pin)
Interface Connector 4
(24-pin)
Interface Connector 2
(20-pin)
Vehicle Connector 1
(24-pin)
Interface Connector 3
(12-pin)
Vehicle Connector 2
(12-pin)
Wiring Connections
Yellow 12v+
Red
Black Ground
Brown Loop Mute Output
Blue Not Used
Blue / White Remote On Input
Orange Not Used
Orange / White Illumination Output
Purple / White Reverse Output (+)
Light Green Parking Brake Output (-)
Pink Vehicle Speed Signal
Purple Rear R + input
Purple / Black Rear R - input
Green Rear L + input
Green / Black Rear L - input
Gray Front R + input
Gray / Black Front R - input
White Front L + input
White / Black Front L - input
Accessory Output
(10 amp)
Output (VSS)
Steering Wheel Control Output Connector
1. The GM1A-RT provides a SWC output connector labeled “Connect to PAC Steering Wheel Control Interface”
(Fig. A). For ease of installation, all necessary connections have been made for you.
2. You can use either a PAC SWI-RC or an SWI-CP2 (sold separately).
a. When using an SWI-RC, the loop on the output connector should remain intact. Set the
SWI-RC to version two and program the buttons according to the SWI-RC instructions.
b. When using an SWI-CP2, use the DIP switch settings provided for the GM1A-RT in the
ControlPRO application. The steering wheel controls will be preconfigured for the vehicle
and radio but can be customized using the ControlPRO PC application. The loop on the
output connector should remain intact.
Fig. A
VS41 Wiring
The VS41 can be connected to the GM1A-RT and used to switch multiple cameras. Please refer to the document labeled
“Instructions for wiring the VS41 into 2003-2006 Chevy / GMC Trucks and SUVs” which can be found on www.pac-audio.
com under the VS41 product page.
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