GMC 2009 Acadia - Manual (Page 379)

Relays Usage
FAN 3 Cooling Fan 3
FOG LAMP Fog Lamps
HI BEAM
High-Beam
Headlamps
HID/LO
BEAM
High Intensity
Discharge (HID)
Low-Beam
Headlamps
HORN Horn
IGN Ignition Main
LT TRLR
STOP/TRN
Trailer Left
Stoplamp and Turn
Signal Lamp
PRK LAMP Park Lamp
PWR/TRN Powertrain
Relays Usage
RR DEFOG
Rear Window
Defogger
RT TRLR
STOP/TRN
Trailer Right
Stoplamp and Turn
Signal Lamp
Stop Lamps
(China
Only)
Stop Lamps
(China Only)
TRLR
BCK/UP
Trailer Back-up
Lamps
WPR Windshield Wiper
WPR HI
Windshield Wiper
High Speed
Service and Appearance Care 5-93