2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 1571
voltage, 42 volt, DC to support the Electric Power Steering (EPS). The APM receives a 42 volt enable command from the Hybrid Powertrain
Control Module (HPCM) over the high speed hybrid GMLAN communication circuit. 42 volt APM functions will run only when the 42 volt APM
enable is active on the high speed hybrid GMLAN communication circuit.
Conditions for Running the DTC
APM 42 volt output commanded on.
Conditions for Setting the DTC
42 volt circuit below 21 volts during operation.
Action Taken When the DTC Sets
* DTC P1A89 is a Type C DTC.
* The APM will shutdown 42 volt conversions.
Conditions for Clearing the DTC
DTC P1A89 is a Type C DTC.
Diagnostic Aids
* DTC C0895 03 EPS Voltage Below Threshold may be set.
* DTC C0895 12 EPS Voltage Below Minimum Threshold may also be set.
* The 42 volt circuit is only used by the EPS. The APM can apply 42 volts on the connector without being connected to the EPS.
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 Verification
1. Start the engine.
2. Using the scan tool, observe the 42V Circuit Voltage parameter on the APM data list.
瀚慖f the voltage is less than 40 volts, proceed to Circuit/System Testing.
3. Rotate the steering wheel back and forth while stationary.
瀚慖f the voltage is less than 40 volts, the EPS is drawing excessive current. Replace the power steering motor.
Circuit/System Testing
1. Disconnect the 42 Volt harness connector at the APM.
2. Turn the ignition to ON.
3. Use the APM Intermediate Voltage Control on the scan tool to turn on the 42 volt circuit.
瀚慖f the voltage is greater than 40 volts, replace the power steering control module (PSCM).
