Savana 4500 V8-6.6L DSL Turbo (2009)
Data Link Communications Description and Operation (See: Description and Operation)
Electrical Information Reference
*
Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics)
*
Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics)
*
Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics)
*
Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics)
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:
*
Control modules the vehicle is equipped with
*
High speed GMLAN serial data circuit terminating resistors
*
Control module locations on the high speed GMLAN serial data circuits
*
Each control module's 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/Data Link References). Communications should not be available with two or more control modules on the
high speed GMLAN serial data circuit.
‹› If only one control module is not communicating, diagnose that control module only; refer to DTC U0100-U0299 (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:
*
Terminal 6
*
Terminal 14
‹› 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:
*
Terminal 6
*
Terminal 14
‹› If not the specified value, test the serial data circuit for a short to ground; refer to Testing the Serial Data Circuits for a Short to ground.
6. Test for 50-70 ohm between the serial data circuits terminal 6 and terminal 14.
‹› If less than 35 ohm, test for a short between the serial data circuits; refer to Testing the Serial Data Circuits for a Short between the Circuits.
‹› If 35-50 ohm there may be a third terminating resistor between the serial data circuits. This can happen if the incorrect control module is
installed. Some control modules are available with and without the terminating resistors installed to reduce the need of terminating resistors in
the wiring harness.
‹› If greater than 70 ohm but less than infinite, test the serial data circuit for an open/high resistance; refer to Testing the Serial Data Circuits for
an Open/High Resistance.
‹› If infinite, test the serial data circuits between the DLC and the first connection to the serial data circuit for an open/high resistance.
Testing the Serial Data Circuits for a Short to Voltage
1. Ignition OFF, disconnect the harness connectors with the high speed GMLAN serial data circuits at an easily accessible control module.
2. Ignition ON, test for greater than 4.5 V between each serial data circuit at the control module connector that was just disconnected and ground.
Verify that one or more serial data circuits are greater than 4.5 V.
‹› If all serial data circuits are less than the specified range, replace the control module that was disconnected.
