Circuit Description
The powertrain control module (PCM) receives rough road information from the electronic brake control module (EBCM) or the electronic brake and traction control module (EBTCM) on the Class 2 serial data circuit. The PCM uses the rough road information to enhance the misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from variations caused by true misfires. The EBCM or EBTCM transmits rough road information based on inputs from the wheel speed sensors. If the EBCM or EBTCM detects a condition which will not allow it to properly identify rough road situations while a misfire condition is being detected by the PCM, DTC P1380 will be set.
Conditions for Running the DTC
| • | The engine load is less than 87 percent. |
| • | The engine speed is less than 5,000 RPM. |
| • | The vehicle speed is more than 10 mph. |
| • | A misfire diagnostic trouble code (DTC) is occurring and requesting the malfunction indicator lamp (MIL) to be illuminated. |
Conditions for Setting the DTC
The PCM has detected an EBCM or EBTCM rough road sensing error.
Action Taken When the DTC Sets
| • | The powertrain control module (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 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | The current DTC will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool in order to clear the MIL diagnostic trouble code. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description , Clearing Diagnostic Trouble Codes. |
Diagnostic Aids
If DTC P1380 is set, the antilock brake system (ABS) / traction control system (TCS) has detected a malfunction which is preventing the EBCM or EBTCM from transmitting correct rough road data to the PCM. Refer to Diagnostic Starting Point in Antilock Brake System.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Diagnostic Starting Point in Antilock Brake System |
