2010 Cadillac Truck Escalade RWD V8-6.2L Page 1559
* DTCs P0C77 and P1A20 are type C DTCs.
* The hybrid powertrain control module will not command the high voltage contactors closed.
Conditions for Clearing the DTC
DTCs P0C77 and P1A20 are type C DTCs.
Diagnostic Aids
Note: If the high voltage contactors opened while under high current load, replace BOTH high voltage contactors. The following conditions could
cause the high voltage contactors to open while under high current load:
* A collision resulting in supplemental inflatable restraint (SIR) deployment.
* A collision that activates the high voltage circuit impact detection (HVCID) sensor.
* A high voltage circuit impact detection sensor circuit fault that occurs while the vehicle is moving.
* A loss of power or ground to the drive motor generator battery control module while the vehicle is moving.
The precharge time can be affected by the following:
* A long precharge time may be caused by an open 125 A fuse in the manual disconnect lever
* A short precharge time may be caused by a positive high voltage contactor stuck.
* A negative high voltage contactor stuck closed will not affect the precharge sequence.
A long or short precharge time may cause any of the following;
The drive motor generator battery control module will start a precharge wait timer after failing 2 consecutive precharge events. The contactors will
not close until the precharge wait time has timed out.
Reference Information
Schematic Reference
* Hybrid Energy Storage Schematics ()
* Hybrid Controls Schematics ()
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Drive Motor Battery System Description ()
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* 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
Special Tools
* EL-48458 HV Precharge Tester
* EL-48569 Terminal Covers
* EL-48900 HEV Safety Kit
Circuit/System Testing
Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal
Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure will perform the following tasks:
