2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2750
Testing the Serial Data Circuits for a Short to Ground
1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control
module.
2. Ignition OFF for 60 seconds, test for less than 1k ohm 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 less than 1k ohm.
瀚慖f all serial data circuits are greater than the specified range, replace the control module that was disconnected.
3. 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 ground.
4. Ignition OFF for 60 seconds, test for less than 1k ohm 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 less than 1k ohm.
瀚慖f greater than the specified range for all serial data circuits, replace the control module that was just disconnected.
5. Repeat step 3 until one of the follow conditions are isolated:
* A short to ground on the serial data circuit between 2 control modules
* A short to ground on the serial data circuit between a control module and a terminating resistor.
Testing the Serial Data Circuits for a Short between the Circuits
1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control
module that is not communicating.
2. Ignition OFF for 60 seconds, test for less than 35 ohm between each pair of serial data circuits at the control module connector that was just
disconnected. Verify that one pair of serial data circuits are less than 35 ohm.
瀚慖f each pair of serial data circuits is greater than the specified range, replace the control module that was disconnected.
3. Connect the harness connectors at the control module that was disconnected.
4. Disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of
the circuits shorted together.
5. Ignition OFF for 60 seconds, test for less than 35 ohm between each pair of serial data circuits at the control module connector that was just
disconnected. Verify that one pair of serial data circuits are less than 35 ohm.
瀚慖f each pair of serial data circuits is within the specified range, replace the control module that was just disconnected.
6. Repeat step 3 until one of the following conditions are isolated:
* Serial data circuits shorted together between 2 control modules
* Serial data circuits shorted together between a control module and a terminating resistor
* A shorted terminating resistor
Testing the Serial Data Circuits for an Open/High Resistance
1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control
module that is not communicating.
2. Ignition OFF for 60 seconds, test for greater than 100k ohm between each pair of serial data circuits at the control module connector that was
just disconnected. Verify that one pair of serial data circuits are greater than 100k ohm.
瀚慖f each pair of serial data circuits is less than the specified range, replace the control module that was disconnected.
3. Connect the harness connectors at the control module that was disconnected.
4. Disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of
the open circuit.
5. Ignition OFF for 60 seconds, test for greater than 100k ohm between each pair of serial data circuits at the control module connector that was
just disconnected. Verify that one pair of serial data circuits are greater than 100k ohm.
瀚慖f each pair of serial data circuits is less than the specified range, replace the control module that was just disconnected.
6. Repeat step 3 until one of the following conditions are isolated:
* An open/high resistance on the serial data circuit between 2 control modules
* An open/high resistance on the serial data circuit between a control module and a terminating resistor
* An open/high resistance terminating resistor
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
