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Home >> GMC >> 2016 >> Terrain SL, Gas >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Cellular System, Entertainment System, And Navigation System) >> Description and Operation >> Radio/Audio System Description and Operation (with Monochrome Display) >> Information Display and Controls >> Radio/HVAC Communications

Radio/HVAC Communications

WARNING: This page is about a different car, the 2015 GMC Terrain and 2015 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Radio/HVAC Communications Flow
GM2323135Courtesy of GENERAL MOTORS COMPANY
Callout Component Name
1 Radio/HVAC Controls
2 Info Display Module
3 Radio
4 HVAC Control Module
5 Data Link Connector
a GMLAN
b Local Interconnect Network-HVAC
c CAN Graphical Interface
d Local Interconnect Network-Radio

The radio/HVAC control is a separate component from the radio. The radio/HVAC controls contain the radio control knobs and buttons for all audio functions.

The radio/HVAC controls operate radio functions through serial data messages. The radio/HVAC controls communicate to the info display module through LIN serial data. The info display module communicates to radio through CGI serial data.

When the operator rotates a radio control knob to change radio stations or increase the volume a message is sent to the radio over serial data. After receiving the message the radio will make the adjustment. Messages communicated between the radio and the radio/HVAC controls and info display include the following:

HVAC data for controls and status indicators is communicated between the radio/HVAC controls and the HVAC control module with a separate LIN serial data circuit. HVAC status screen information from the HVAC control module is transmitted to the radio on the GMLAN serial data circuit. The radio then displays the desired screen information on the info display using the video data circuits.