2010 Cadillac CTS Sedan AWD V6-3.0L Page 1524
DTC P0621 is a C type DTC.
Reference Information
Schematic Reference
Starting and Charging Schematics (See: Starting and Charging/Diagrams/Electrical Diagrams)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Charging System Description and Operation (See: Starting and Charging/Charging System/Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
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
LSA or LF1 Engine
1. Verify that a test lamp illuminates between the generator B+ and ground.
瀚慖f the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
2. Ignition OFF, disconnect the X1 harness connector at the generator.
3. Ignition ON, test for 4.5-5.5 V between the control circuit terminal 1 and ground.
瀚慖f greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
瀚慖f less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal replace
the ECM.
4. If the circuits test normal, replace the generator.
LLT Engine
1. Verify that a test lamp illuminates between the generator B+ X2 and ground.
瀚慖f the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
2. Ignition OFF, disconnect the X1 harness connector at the generator.
3. Ignition ON, test for less than 1 V between the control circuit terminal 1 and ground.
瀚慖f greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Engine running, test for greater than 3.5 V between the control circuit terminal 1 and ground.
瀚慖f less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal replace
the ECM.
5. If the circuits test normal, replace the generator.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Generator Replacement (LF1/LLT) (See: Starting and Charging/Charging System/Alternator/Service and Repair)Generator Replacement
(LSA) (See: Starting and Charging/Charging System/Alternator/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
