i have a 91 cummins 4x4 with auto trans. 97 cummins engine (if that matters) and my speedometer doesnt work. to out the sensor from the transfer case and all the gears appear the be fine, not stripped. hooked ohm meter to plug and there was .5 volts. ist that enough? also hooked ohm meter to to sensor and turned it and gave a signal. so im pretty sure that all of that is fine. what else could be the problem? thanks.