DIESEL TANDEM CURVEBALL

DIESEL CHARGING SYSTEMS CAN BE A LITTLE TRICKIER THAN THEIR GASOLINE COUNTERPARTS I had a shop call me for advice on a 2002 Dodge Ram Truck with a 5.9L diesel engine that had a charging system issue (Figure 1). [...]The ECM on this truck most likely took the crank sensor signal input and internally reduced the frequency of the signal delivered to the PCM for some type of strategy reason. The code in the PCM only validated that the alternator field circuits had a power feed or switching ground issue that was pointing you to a wiring fault or a possible bad PCM with an internal alternator field driver failure. [...]it took some out-ofthe-box thinking to unmask the true culprit.