01-04 Chevrolet Silverado/GMC Sierra C/K2500HD C/K3500 6.6L LB7 Enginewith a No Charge Condition with DTC P0380 P0621- kw battery diesel ECM fuse generator voltage

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Vehicles equipped with the 6.6 Duramax diesel engines RPO LB7 may have a no charge condition that may be accompanied by DTC P0380 and P0621. Following published diagnostics for DTC P0621 or a no charge condition may lead to unnecessary generator or ECM replacement.

Following published diagnostics for DTC P0380, P0621 or a no charge condition may lead to unnecessary generator or ECM replacement. You should first check the 175-amp battery fuse. If the 175-amp battery fuse OR circuit 506 is open, no voltage will be present on circuit 506 at the PCM. This will cause the P0380 to set. The ECM monitors the glow plug signal using circuit 506. The ECM expects to see battery voltage on circuit 506 when the glow plugs are commanded on. If no voltage is present on circuit 506, the ECM will stop sending the turn on voltage to the generator L terminal circuit 25, causing the no charge condition and the P0621 to set.

.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(2001-2004 Chevy C Silverado 2WD) and (2001-2004 Chevy K Silverado 4WD) and (2001-2004 GMC C Sierra 2WD) and (2001-2004 GMC K Sierra 4WD)

.