My wife was driving her '04 Dodge 3500 5.9 Cummins on the freeway at 80 mph, the tension arm broke at some point she lost power steering and then brakes. She's wondering, with very good reason, why there were no warning lights or alarms? We had a '97 Ford F350 and 2 squirrels took out our belt and every light and alarm went off - luckily it was parked. Why no warnings on our Dodge?

 

It seems like the battery light would have come on, or at least the check engine light.

 

This does not make sense.
On the Cummins Diesel the power steering pump is gear driven. It sits below the injection pump and behind the vacuum pump. The serpentine belt drives the water pump, A/C compressor, alternator and cooling fan. The vacuum pump and power steering are not belt driven.

 

Also..Wasn't 2002 the last year they used the 5.9?

 

No, 2006 was the last for the 5.9L.
The 6.7L is basically the same design however.
Few more electronics and variable vane turbo.

 

I thought the 6.7 had more valves. I don't know much about diesel engines though.

 

The 6.7L is a 4 valve per cylinder design with cam in block.
In Ram trucks the 5.9L had a 2 valve head(12 valve) from 1989-1998. From 1998.5-2007 it had a 4V head(24 valve).