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 rotation 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 P1381 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1381 Misfire Detected-No Communication With Brake Control Module
Conditions for Running the DTC
| • | The vehicle speed is more than 8 km/h (5 mph). |
| • | The engine speed is less than 7,000 RPM. |
| • | The engine load is less than 60 percent. |
| • | Engine misfire is detected and DTC P0300 is set with the MIL illuminated. |
| • | DTC P1381 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | A serial data malfunction exists preventing the PCM from receiving rough road detection data. |
| • | The above conditions met for 20 seconds. |
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. |
