ION L4-2.4L (2007)
Step 16 - Step 22
The numbers below refer to the step numbers on the diagnostic table.
2. A partial loss of communication in the class 2 serial data circuit uses a different procedure than a total loss of communication of the class 2 serial
data circuit.
4. The following DTCs may be retrieved with a history status. These DTCs are not the cause of the present condition.
* U1300
* U1301
* U1305
6. A State of Health (SOH) DTC with a history status may be present along with a U1000 or U1255 with a current status. This indicates that the
malfunction occurred when the ignition was on.
10. Normal class 2 serial data communication cannot take place until the power mode master (PMM) module sends the appropriate power mode
message. If the PMM does not send a wake-up message, other modules on the class 2 serial data circuit may not communicate.
12. This step will isolate a wiring problem or a module malfunction.
13. An open circuit at this point will cause a loss of communication with the vehicle.
14. This step analyzes the specific branch circuit for a malfunction.
19. If there are no current DTCs that begin with the letter "U", the communication concern has been repaired.
20. The communication concern may have prevented diagnosis of the customer complaint.
Scan Tool Does Not Communicate with High Speed GMLAN Device
Scan Tool Does Not Communicate with High Speed GMLAN Device
Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation.
Operating information and commands are exchanged among the modules. When a module detects a bus-off condition a DTC U2100 will be set. This
DTC can be retrieved as history only.
Diagnostic Aids