Axxess GMOS-MOST-02 Installation Instructions Manual

Attention! Let the vehicle sit with the key

out of the ignition for a few minutes before
removing the factory radio. When testing the
aftermarket equipment, ensure that all factory
equipment is connected before cycling the
key to ignition.

GMOS-MOST-02

INSTALLATION INSTRUCTIONS

AxxessInterfaces.com © COPYRIGHT 2018 METRA ELECTRONICS CORPORATION REV. 9/28/18 INSTGMOS-MOST-02

INTERFACE FEATURES

INTERFACE COMPONENTS

TOOLS REQUIRED

• Crimping tool and connectors, or solder gun,
solder, and heat shrink

• Small flat blade screwdriver • Tape

• Wire cutter • Zip ties

TABLE OF CONTENTS

Connections .........................................................2-3

Installation .............................................................3

Programming .........................................................4

Audio level adjustment .........................................4

GM MOST® Amplifier Interface 2014-up*

APPLICATIONS

• Provides accessory power
(12-volt 10-amp)

•

Maintains the retained
accessory power (R.A.P.) feature

• Retains OnStar / OE Bluetooth

• Retains warning chimes

• Provides NAV outputs (parking
brake, reverse, speed sense)

• Pre-wired ASWC-1 harness
(ASWC-1 sold separately)

• Retains the factory backup
camera

• Used in MOST ® amplified
applications

• Retains balance

• Micro “B” USB updatable

CHEVROLET

Corvette 2014-up

Impala 2014-up

• GMOS-MOST-02 interface

• GMOST-MOST-02 harness

• 16-pin harness with stripped leads

• Backup camera harness

• 10-pin jumper harness

*Visit AxxessInterfaces.com for up-to-date vehicle specific applications.

2

CONNECTIONS

From the 16-pin harness with stripped leads to the aftermarket radio:

• Connect the Red wire to the accessory wire.
Note: If installing an ASWC-1 (sold separately), there will be an accessory wire there to

connect as well.

• Connect the Blue/White wire to the amp turn on wire. This wire must be connected to hear

sound from the factory amplifier.

• If the aftermarket radio has an illumination wire, connect the Orange/White wire to it.

• If also installing an ASWC-1 (sold separately), connect the Brown wire to the Brown wire in

the 12-pin pre-wired ASWC-1 harness.

• Connect the Gray wire to the right front positive speaker output.

• Connect the Gray/Black wire to the right front negative speaker output.

• Connect the White wire to the left front positive speaker output.

• Connect the White/Black wire to the left front negative speaker output.

• Connect the Green wire to the left rear positive speaker output.

• Connect the Green/Black wire to the left rear negative speaker output.

• Connect the Purple wire to the right rear positive speaker output.

• Connect the Purple/Black wire to the right rear negative speaker output.

The following (3) wires are only for multimedia/navigation radios that require these wires.

• Connect the Blue/Pink wire to the VSS/speed sense wire.

• Connect the Green/Purple wire to the reverse wire.

• Connect the Light Green wire to the parking brake wire.

From the GMOS-MOST-02 harness to the aftermarket radio:

• Connect the Black wire to the ground wire.

• Connect the Yellow wire to the battery wire.

• Connect the Brown wire, to the Brown wire from the

16-pin harness with stripped leads

.

• Disregard the Red wire, it will not be used in this application.

• Disregard the Red & White RCA jacks, they will not be used in this application.

12-pin pre-wired ASWC-1 harness:

This harness is to be used along with the ASWC-1 (sold separately) to retain steering wheel
audio controls. If the ASWC-1 is not being used, disregard this harness. If it will be used,
please refer to the ASWC-1 instructions for radio connections and programming. Disregard
the harness that comes with the ASWC-1.

• Connect the Red wire to the

accessory wire.

• Connect the Green/Black
wire, to the Green/Black wire
in the 10-pin Black connector
located in the steering
column. (Figure A)

(Figure A)

Green/Black wire

Continued on the next page

3

REV. 9/28/2018 INSTGMOS-MOST-02

CONNECTIONS (CONT.) INSTALLATION

DIN jack:

• Disregard the DIN jack, it will not be used in this application.

Note: The relay attached to the GMOS-MOST-02 harness is only for audible turn signal clicks. No
extra steps are required to retain this feature, so leave the relay as-is.

From the backup camera harness to the aftermarket radio:

• If the vehicle is equipped with a factory backup camera, connect the Yellow RCA jack to the

backup camera input.

With the key in the off position:

• Locate the radio brain and Human Machine Interface module (HMI):

Corvette:

• Radio Brain: Passenger foot-well

• HMI: Left side of dash

Impala:

• Radio Brain & HMI: Under passenger side dashboard

• Connect the

GMOS-MOST-02 harness

to the 20-pin Gray connector, and 8-pin Light Gray

connector, removed from the radio brain.

• Connect the

backup camera harness

to the 12-pin Gray connector removed from the

HMI module.

• Connect the

16-pin harness with stripped leads

, and the

GMOS-MOST-02 harness

, into the

GMOS-MOST-02 interface.

• If the vehicle is equipped with a media player, connect the

10-pin jumper harness

to the

connector removed from the media player.

Note: If also installing an ASWC-1, connect it after you program and test the GMOS-MOST-02,

with the key in the off position.