As noted in the US Manual:
LED Auxiliary High Beam Lights: Switch on or off to prime the LED Auxiliary High Beam Lights. When the main beam is switched on, then the LED Auxiliary High Beam Lights will activate. Off-Road/Wading Mode must be activated.
LED auxiliary lights The Grenadier as standard is fitted with LED Auxiliary Lights. These LED auxiliary high beam lights are in the front grill and are designed for off-road use only. The LED Auxiliary Lights can only be activated with the high beam switched on and Off-Road or Wading mode is active. WARNING: The LED Auxiliary Lights are for use only off road when local laws and regulations permit. They are strictly for off-road purposes and could temporarily blind drivers in oncoming traffic. To Activate LED Auxiliary Lights:
1. Switch on the ignition and press the auxiliary light button in the Overhead Control Panel. 2. The LED in the button will be illuminated to show the system is active. 3. When the headlights are turned on, the auxiliary lights will now also be illuminated.