Have just replaced the PCM on 92 w-250 after the original let the alternator quit charging, would not let overdrive engage, and all dash lights would occasionally stay on then go out. I replaced it with a remanufactured unit and after a day and probably 25 miles thinking that everything was ok, the voltmeter has started going from normal at times to around 10v and the speedometer stays at 0 then jumps to actual speed and then back to 0. Everything else including overdrive works fine. Have checked all ground circuits and they appear to be OK. I'm thinking I probably got a "remanufactured" unit with a problem.