My first port of call would be to check the relay responsible for the lights.
I have known of stalks to completely fail in Vauxhalls before so it could be that if the alarm is patched into the stalk as apposed straight to the relay.
	
		
			
		
		
	
				
			I have known of stalks to completely fail in Vauxhalls before so it could be that if the alarm is patched into the stalk as apposed straight to the relay.
 
	 
  
 
		 
		 
 
		