Circuit Description
The powertrain control module (PCM) receives rough road information
from the electronic brake control module (EBCM) on the 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 transmits rough road information based
on inputs from the wheel speed sensors. If the EBCM 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 set.
Conditions for Running the DTC
| • | Engine load is less than 87 percent. |
| • | Engine speed is less than 5000 RPM. |
| • | Vehicle speed is more than 16 km/h (10 mph). |
| • | A Misfire DTC is occurring and requesting the malfunction indicator
lamp (MIL) to be illuminated. |
Conditions for Setting the DTC
The PCM has detected a EBCM rough road sensing error.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when
the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time
the diagnostic fails. The control module stores this information in the Failure
Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs
and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles,
if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
