2010 Cadillac Truck Escalade RWD V8-6.2L Page 1569
Circuit/System Description
The accessory dc power control module (APM) converts the energy that flows between the high voltage, 300 volt, direct current (DC) to
intermediate 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.
The APM continuously monitors the status of its 42 volt circuitry. It will do some diagnostics on this circuitry when the ignition key is first turned
to RUN. Additional diagnostics are run while the APM is doing 42 volt conversions after receiving the 42 volt enable command.
Conditions for Running the DTC
* Ignition voltage is 7-16 volts.
* The APM runs a portion of the diagnostics for this DTC at Accessory/Ignition On.
* The APM runs more diagnostics when the 42 volt output is commanded on.
Conditions for Setting the DTC
* An external condition has caused an APM 42 volt malfunction,
OR
* The APM has detected an internal malfunction.
Action Taken When the DTC Sets
* DTC P1A88 is a Type C DTC.
* The APM will shutdown 42 volt conversion.
Conditions for Clearing the DTC
DTC P1A88 is a Type C DTC.
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. This DTC can set as a result of conditions external to the APM. Before attempting to diagnose this DTC, ensure the following conditions
have not been encountered:
* High voltage contactor relays opening any time the APM is doing 42 volt conversion.
* The high voltage system is greater than 390 volts or less than 216 volts during 42 volt conversion. Extreme cold weather conditions may
occasionally cause the high voltage system to be greater than 390 volts.
* The 12 volt circuit is less than 6.7 volts during 42 volt conversion.
* A short circuit condition on the 42 volt circuit which causes the APM to produce greater than 60 amps.
瀚慖f any of the above APM-external conditions have occurred, diagnose the conditions as applicable and clear the DTC Information. No
further diagnosis of this DTC is required.
瀚慖f none of the above APM-external conditions have been encountered, continue with Circuit/System Verification.
