2010 Cadillac Truck Escalade RWD V8-6.2L Page 1553
Action Taken When the DTC Sets
* DTC P1A8A is a Type C DTC.
* The APM will shutdown 42 volt conversions.
Conditions for Clearing the DTC
* DTC P1A8A is a Type C DTC.
* 42 volt circuit is below 48 volts.
Diagnostic Aids
* DTC C0895 07 EPS Voltage Above Threshold may be set.
* The APM Data List on the scan tool contains a parameter named 42V Circuit Maximum. If this parameter has a voltage that is greater than 50
volts, the protection circuits in the power steering control module (PSCM) have failed and as a result, this is not a fault condition in the APM.
Reference Information
Schematic Reference
Hybrid Controls Schematics ()
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Drive Motor Generator Control Module Description and Operation ()
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Testing
1. Start the engine.
2. Using the scan tool, observe the 42V Circuit Voltage parameter on the APM data list.
瀚慖f the 42V Circuit Voltage parameter is greater than 48 volts, replace the APM.
瀚慖f the 42V Circuit Voltage parameter is less than 48 volts, replace the PSCM.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
Control Module References (See: Testing and Inspection/Programming and Relearning) for APM or PSCM replacement, setup, and programming.
P1A8B
DTC P1A8B or P1A8C
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
