Circuit Description
The class 2 circuit connects to various modules. These modules monitor the link for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules on the data link. When a module receives a critical operating parameter from another module, the receiving module records the identification number from the module that sent the message. This is called State of Health Monitoring (SOH). A critical operating command will have the sending module's identification number attached with it. Once an identification number is learned by a module, it will continue to monitor for that number. When no message is detected from a learned identification number for a set time, a code is set in the module that was monitoring the identification number.
Conditions for Running the DTC
The ignition voltage is greater than 9.5 volts, but less than 18.0 volts.
Conditions for Setting the DTC
| • | The PCM does not detect a valid Class 2 message. |
| • | The PCM detects a low voltage (shorted to ground) on the Class 2 circuit. |
| • | All conditions met for 3.0 seconds. |
Action Taken When the DTC Sets
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | A last test failed (Current DTC) will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool in order to clear the MIL/DTC. |
Diagnostic Aids
This DTC cannot be displayed on a scan tool when the fault is active. The scan tool will not communicate with an active DTC U1300.
The communication DTCs are for information only. Refer to Scan Tool Does Not Communicate with Class 2 Data Line in Wiring Systems for further diagnosis.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Scan Tool Does Not Communicate with Class 2 Data Line in Wiring Systems. |
