Chevy C5500 Speedo stuck at 85, governor kicks in
 

It's a long story, but at work we relinquished a beat up 01-05 (not sure) C5500 box truck with the 6.6 from one of our sister companies. The batteries were both shot and it had two flat tires. We got it running and in ship-shape condition and now the speedometer is stuck at 85 and it won't go faster than 30mph (says the GPS). I'm assuming that the governor is kicking in or something...?

Could this be the infamous stepper motor problem I've heard about with earlier Duramaxs? If so, how would we go about getting this taken care of?


By the way, we can't actually get this truck serviced because one company bought out the rights to all 5500 series trucks in Michigan and they are the only truck dealer allowed to service them. (*(&^%(&*^(*&^%$%(*^(*&^_(*&^) not even a chevy dealer is allowed to help us. They could if it's a 4500. This is stupid. The company that bought it out is 2 hours away too.