Circuit/System Testing: Notes
NOTE:
Use the schematic to identify the following:
- Control modules the vehicle is equipped with
- Control module locations on the low speed GMLAN serial data circuit
- The low speed GMLAN serial data circuit terminals for each control module
- Attempt to communicate with all control modules on the low speed GMLAN serial data circuit, refer to Data Link References . Communications should not be available with two or more control modules on the low speed GMLAN serial data circuit.
- If only one control module is not communicating, diagnose that control module only, refer to DTC U0100-U0299 .
- If one or more control modules are communicating but not all, refer to Testing the Serial Data Circuit for an Open/High Resistance .
- Disconnect the scan tool from the DLC. The following tests will be done at the DLC connector.
- All access doors closed, ignition OFF for 60 seconds, test for less than 10 Ω between the ground circuit terminal 5 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition ON, test for less than 4.5 V between the serial data circuit terminal 1 and ground.
- If greater than the specified range, test the serial data circuit for a short to voltage, refer to Testing the Serial Data Circuit for a Short to Voltage .
- Ignition OFF for 60 seconds, test for greater than 100 Ω between the serial data circuit terminal 1 and ground.
- If less than the specified range, test the serial data circuit for a short to ground, refer to Testing the Serial Data Circuits for a Short to ground .
- Disconnect the appropriate harness connector at the JX 200 splice pack.
- Test for less than 2 Ω between the DLC serial data circuit terminal 1 and the JX200 splice pack terminal 1.
- If greater than the specified range, test the serial data circuit for an open/high resistance. If the circuits test normal, replace the splice pack.