After talking to some other Jeep engineers, we knew that there was a 5-volt signal going to the speedometer pickup in the transfer case. What we didn't know was the amperage. So, we got a bunch of potentiometers to dial in 5 volts at different amperages. We fried two potentiometers, and on our third one, we think we fried the speedometer sensor. It got hot, smelled burnt, and we decided that there were other things to look at.