Sky L4-2.0L Turbo (2008)
Attempt to communicate with all modules on the high speed GMLAN bus.
If any high speed module communicates and any DTC beginning with a U exists, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Testing
and Inspection/Diagnostic Trouble Code Descriptions) for diagnostics.
If any high speed module communicates and no DTC beginning with a U exists, refer to DTC U0100-U0299 or U2105-U2199 for diagnostics.
Circuit/System Testing
High Speed GMLAN Initial Test
1. Test for less than 1.0 ohm of resistance between the DLC ground circuit terminal 5 and ground.
‹› If greater than the specified range, test the ground circuit for an open/high resistance.
2. Disconnect the harness connector at the EBCM.
3. Ignition ON, attempt to communicate with the BCM.
‹› If communication is established refer to DIAGNOSTIC 2.
‹› If communication is not established, refer to DIAGNOSTIC 1.
DIAGNOSTIC 1
1. Ignition OFF, disconnect the X2 harness connector at the BCM.
2. Ignition OFF, test for less than 2 ohms of resistance between the DLC serial data circuit terminal 6 and BCM serial data circuit terminal 1.
‹› If greater than the specified range, test the serial data circuit for open/high resistance.
3. Ignition OFF, disconnect the X1 and X4 harness connectors at the BCM.
4. Test for less than 5 ohms of resistance between the following ground circuit terminals and ground.
*
X1 terminal 61
*
X4 terminal E12
‹› If greater than the specified range, test the ground circuit for an open/high resistance.
5. Ignition OFF, disconnect the X3 harness connectors at the BCM.
6. Ignition ON, verify a test lamp illuminates between the following B+ circuit terminals and ground.
*
X3 terminal D12
*
X3 terminal D1
‹› If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the
B+ output circuits for a short to ground.
7. Ignition OFF, test for infinite resistance between the following serial data circuits of the DLC and ground.
*
Terminal 6
*
Terminal 14
‹› If less than the specified value, test the serial data circuits for a short to ground.
8. Ignition ON, test for less than 1 volt between the following serial data circuits of the DLC and ground.
*
Terminal 6
*
Terminal 14
‹› If greater than the specified range, test the serial data circuit for a short to voltage.
9. Ignition OFF, test for infinite resistance between the DLC serial data circuit terminal 6 and terminal 14.
‹› If less than the specified value, test for a short between the serial data circuits.
10. Connect the X1, X2, X3 and X4 harness connector at the BCM.
11. Ignition OFF, disconnect the X4 harness connector at the VCIM.
12. Ignition ON, attempt to communicate with the BCM. Communication should not be available.
‹› If communication is established, test the following serial data circuits between the VCIM and the EBCM for a short between the circuits, short
