System Description
The powertrain control module (PCM) detects engine misfire events by monitoring variations in the crankshaft rotation speed. Wheel speed changes caused by rough road conditions can cause changes in crankshaft speed. By monitoring the wheel speed sensors, the antilock brake system (ABS) can determine if the vehicle is operating on a rough road. If the ABS is detecting a rough road condition severe enough to effect misfire detection, a rough road signal is sent to the PCM on the serial data circuit. If DTC P0300 is set with the malfunction indicator lamp (MIL) illuminated, and the rough road information is not available due to an ABS malfunction, DTC P1380 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1380 Misfire Detected - Rough Road Data Not Available
Conditions for Running the DTC
| • | The vehicle speed is more than 8 km/h (5 mph). |
| • | The engine load is less than 60 percent. |
| • | The engine misfire is detected and DTC P0300 is set with the MIL illuminated. |
| • | The engine speed is less than 7,000 RPM. |
| • | DTC P1380 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
An ABS malfunction exists for more than 45 seconds, preventing the PCM from receiving rough road detection data.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | 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. |
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Does the scan tool display any antilock brake system (ABS) DTCs? |
