It is best to carry a spare RCM because you can change one in 5 minutes, and it contains relays for multiple functions. They have been known to fail at low mileage, usually faulty solder joints and at high mileage, usually from worn or sticky relays. They just unplug. I have never had a belt tensioner fail but they do. Usually at high mileage. Because of age it would be prudent to change the belt and keep the old one as backup.









M