diff --git a/ArduCopter/config_channels.h b/ArduCopter/config_channels.h
index fe6677e42a..b3a1e7263d 100644
--- a/ArduCopter/config_channels.h
+++ b/ArduCopter/config_channels.h
@@ -49,8 +49,7 @@
 //
 //
 #if CONFIG_APM_HARDWARE == APM_HARDWARE_APM2
-/* TODO find out correct channel for APM2 TRI_YAW */
-# define CH_TRI_YAW   (-1)
+# define CH_TRI_YAW   CH_7
 #elif CONFIG_APM_HARDWARE == APM_HARDWARE_APM1
 # define CH_TRI_YAW   CH_7
 #endif
diff --git a/ArduCopter/motors_tri.pde b/ArduCopter/motors_tri.pde
index dda4ba7638..3fbdb49e8f 100644
--- a/ArduCopter/motors_tri.pde
+++ b/ArduCopter/motors_tri.pde
@@ -13,6 +13,7 @@ static void motors_output_enable()
   APM_RC.enable_out(MOT_1);
   APM_RC.enable_out(MOT_2);
   APM_RC.enable_out(MOT_4);
+  APM_RC.enable_out(CH_TRI_YAW);
 }