2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2749
* 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)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
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
* Powertrain High Speed GMLAN serial data circuit terminating resistors
* Control module locations on the Powertrain High Speed GMLAN serial data circuits
* Each control module's Powertrain High Speed GMLAN serial data circuit terminals
1. Attempt to communicate with all control modules on the Powertrain High Speed GMLAN serial data circuit, refer to. Communications
should not be available with two or more control modules on the Powertrain High Speed GMLAN serial data circuit.
瀚慖f only one control module is not communicating, diagnose that control module only; refer to.
2. Disconnect the scan tool from the DLC. The following tests will be done at the DLC connector.
3. Ignition ON, test for less than 4.5 V between the serial data circuits listed below and ground:
* Terminal 3
* Terminal 11
瀚慖f 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.
4. Ignition OFF for 60 seconds, test for greater than 100 ohm between the serial data circuit listed below and ground:
* Terminal 3
* Terminal 11
瀚慖f 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.
5. Test for 50-70 ohm between the serial data circuit terminal 3 and terminal 11.
瀚慖f 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.
瀚慖f 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.
瀚慖f 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.
瀚慖f 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 Powertrain 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.
瀚慖f all serial data circuits are less than the specified range, replace the control module that was disconnected.
3. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in
the direction of the circuit shorted to voltage.
4. Ignition ON, test for greater than 4.5 V between the serial data circuits 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.
瀚慖f all serial data circuits are less than the specified range, replace the control module that was just disconnected.
5. Repeat step 3 until one of the follow conditions are isolated:
* A short to voltage on the serial data circuit between 2 control modules
* A short to voltage on the serial data circuit between a control module and a terminating resistor.
