LaCrosse FWD V6-3.0L (2010)
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The engine will not start when there is a total malfunction of the high speed GMLAN serial data bus.
These conditions may be caused by the installation of an aftermarket navigation radio module (see bulletins). Some customers may comment of
one or more of the following concerns:
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Vehicle will not crank
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Vehicle cranks but will not start
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Vehicle stability enhancement system warning lights and messages
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PRNDL gear indicator position errors
Reference Information
Schematic Reference
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Data Communication Schematics (See: Diagrams/Electrical Diagrams)
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Control Module References (See: Testing and Inspection/Programming and Relearning)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Data Link Communications Description and Operation (See: Description and Operation)
Electrical Information Reference
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Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
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Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
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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)
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Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Testing
Note: Each control module may need to be disconnected to isolate a circuit fault. Use the schematic to identify the following:
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Control modules the vehicle is equipped with
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Chassis high speed GMLAN serial data circuit terminating resistors
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Control module locations on the chassis high speed GMLAN serial data circuits
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Each control module chassis high speed GMLAN serial data circuit terminals
1. Attempt to communicate with all control modules on the high speed GMLAN serial data circuit. Refer to Data Link References (See: Initial
Inspection and Diagnostic Overview). Communications should not be available with two or more control modules on the chassis high speed
GMLAN serial data circuit.
‹› If only one control module is not communicating, diagnose that control module only. Refer to DTC U0100-U02FF (See: Testing and
Inspection/Diagnostic Trouble Code Tests and Associated Procedures/U Code Charts/U0100).
2. Disconnect the scan tool from the DLC. The following tests will be done at the DLC connector.
3. All access doors closed, ignition OFF for 60 seconds, test for less than 10 ohm between the ground circuit terminal 5 and ground.
‹› If greater than the specified range, test the ground circuit for an open/high resistance.
4. Ignition ON, test for less than 4.5 V between the serial data circuits listed below and ground:
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Terminal 12
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Terminal 13
‹› If greater than the specified range, test the serial data circuit for a short to voltage. Refer to Testing the Serial Data Circuits for a Short to
Voltage.
5. Ignition OFF for 60 seconds, test for greater than 100 ohm between the serial data circuits listed below and ground:
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Terminal 12
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Terminal 13
