DTC P0A27 or P1A58. GMC Truck GMC Sierra Denali 2006

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2006 🢒 GMC Sierra Denali 🢒 Restraints 🢒 SIR 🢒 DTC P0A27 or P1A58

The energy storage control module (ESCM) will monitor the battery cut off switch for over voltage or an open.

This diagnostic procedure supports the following DTCs:

•	DTC P0A27 Hybrid Battery Pack Relay Feedback Circuit

•	DTC P1A58 Hybrid Battery Pack Relay Open

•	Engine is running for 30 seconds.

•	The ESCM has turned ON and no configuration DTC is present.

•	This diagnostic shall run every 100 milliseconds.

•	Reference voltage is stable and accurate.

•	P0A27 - Battery cut off switch status is greater than 5.35 volts.

•	P1A58 - The ESCM senses that the battery cut off switch is open.

•	The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.

•	The malfunction indicator lamp (MIL) will not illuminate.

•	The driver information center, if equipped, may display a message.

•	A current DTC Last Test Failed clears when the diagnostic runs and passes.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

•	Clear the DTC with a scan tool.

Step	Action	Yes	No
Schematic Reference: Starting and Charging Schematics Connector End View Reference: Engine Electrical Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. With a scan tool observe the energy storage control module (ESCM) DTC list. Is the DTC set as current DTC?	Go to Step 4	Go to Testing for Intermittent Conditions and Poor Connections
3	Test the BCO Status circuit of the battery cut off switch for a short to voltage above 5.5 volts or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 6	Go to Step 4
4	Inspect for poor connections at the harness connector of the battery cut off switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 6	Go to Step 5
5	Replace the battery cut off switch. Refer to Battery Service Disconnect Switch Replacement . Did you complete the replacement?	Go to Step 6	--
6	Use the scan tool in order to clear the DTCs . Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?	Go to Step 2	System OK