Subject: | Battery Not Charging Message, Battery MIL, Voltage Gauge Flux and/or DTC P0A8B |
Models: | 2004-2007 Chevrolet Silverado Classic |
2004-2007 GMC Sierra Classic |
with RPO HP2 |
This PI is being updated to add 2007 Model Year. Please discard PIT3643A
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Some owners may comment of a volt gauge fluctuation, lights dimming, blower speed changing, Battery Not Charging Message, Battery MIL and/or DTC P0A8B. During normal diagnostics, it may be noticed that the voltage in the SGCM Data Parameter "12 Volt Converter Output Voltage" is fluctuating between approximately 0 to 20 volts. This concern may be caused by a loose or blown 175 Amp Mega Fuse connected to the UBEC see Document ID # 1433395 and 1433394.
To correct this concern, replace or tighten the 175 Amp Mega Fuse. If the 175 Amp Mega Fuse is blown, inspect for a shorted circuit.
Note: When checking the 175 Amp Mega Fuse, voltage will be present on both sides of the fuse, even when blown. To check the fuse, remove it and check with an ohm meter.
Please follow this diagnostic or repair 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.