2006 Land Rover Range Rover Aux cooling pump

i have a 2006 Supercharged 4.2L RangeRover, that does not like to tow my trailer. I keep getting a fault code that pertains to auxiliary coolant pump isiues whenever I tow my tandem axle trailer .

Have you had the pump tested?

Just what IS that fault code? How heavy is your trailer? How many miles on this Range Rover? Please post.