Circuit Description
Rough roads cause torque on the tires that is transmitted to the powertrain.
This slows down the crankshaft giving the appearance of a misfire.
The electronic brake and traction control module (EBTCM) determines
rough road surfaces using input from the wheel speed sensors.
The EBTCM then sends the rough road data to the powertrain
control module (PCM) via class 2 serial data. The PCM uses the rough
road data to enhance the misfire diagnostic. The data allows
the PCM to distinguish the crankshaft speed variations caused
by rough road surfaces from those caused by true misfires.
If the EBTCM is unable to identify rough road conditions while
the PCM detects a misfire condition, diagnostic trouble code (DTC) P1380
will set.
Conditions for Running the DTC
| • | The engine load is less than 100 percent. |
| • | The engine speed is less than 6,500 RPM. |
| • | The vehicle speed is more than 1 km/h (0.6 mph). |
| • | A misfire DTC is occurring and requesting the malfunction indicator
lamp (MIL) to be illuminated. |
Conditions for Setting the DTC
The PCM detects an EBTCM 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. |
Diagnostic Aids
DTC P1380 set indicates that the anti--lock brake/traction
control system (ABS/TCS) has detected a malfunction which will not
allow the EBTCM to transmit correct rough road data to
the PCM.
If the condition is intermittent, refer to
Intermittent Conditions
in Symptoms - Engine Controls.
