Circuit Description
Each control module connected to the class 2 serial data circuit monitors
the voltage on the circuit. If a control module detects the class 2 serial
data circuit is open or shorted for 3 seconds, all other class 2 serial
communication DTCs are inhibited and DTC U1300, U1301, or U1305 will set.
DTC Descriptors
This diagnostic procedure supports the following DTCs.
| • | DTC U1300 Class 2 Data Link Low |
| • | DTC U1301 Class 2 Data Link High |
| • | DTC U1305 Class 2 Data Link Low or High |
Conditions for Running the DTCs
| • | Voltage supplied to the module is in the normal operating voltage range. |
| • | The vehicle power mode requires serial data communication to occur. |
Conditions for Setting the DTCs
| • | No valid messages are detected on the class 2 serial data circuit. |
| • | The voltage level detected on the class 2 serial data circuit is
always low or always high. |
| • | The above conditions are met for 3 seconds. |
Action Taken When the DTCs Sets
| • | The module inhibits the setting of all other class 2 DTCs. |
| • | The module uses default values for all parameters received on the class 2
serial data circuit. |
Conditions for Clearing the DTC
| • | A current DTC clears when the malfunction is no longer present, or when
the ignition is cycled. |
| • | A history DTC clears when the ignition has been cycled 100 times,
without a repeat of the malfunction. |
Diagnostic Aids
| • | DTCs U1300, U1301, and U1305 cannot be retrieved while the condition
is present. Diagnosis of these DTCs is accomplished via the symptom Scan Tool Does
Not Communicate with a Class 2 Device. Refer to
Scan Tool Does Not Communicate with Class 2 Device
. |
| • | An intermittent condition is likely to be caused by a short or an open
on the class 2 serial data circuit. Use the Scan Tool Does Not Communicate
with a Class 2 Device procedure in order to isolate an intermittent
condition. Refer to
Scan Tool Does Not Communicate with Class 2 Device
. |
