P1380

System Description
The Powertrain Control Module (PCM) identifies engine misfire by detecting variations in crankshaft speed. Crankshaft speed variations can also occur when a vehicle is operated over a rough surface. The Anti-Lock Brake System (ABS) can detect when the vehicle is on a rough surface based on wheel acceleration/deceleration data supplied by each wheel speed sensor. This information is sent to the PCM by the Electronic Brake Control Module (EBCM) over the UART serial data line. The PCM then uses this information to determine if the crankshaft variations are being caused by an actual engine misfire or from being driven on a rough surface.
Whenever the ABS is found to be malfunctioning, the PCM will still continue to detect for misfire. However, if a misfire DTC is set, this additional DTC P1380 will also be set, indicating that rough surface data was not usable during the misfire detection due to the ABS malfunction.

Conditions for Setting the DTC
- DTC P0300-P0304 has been set.
- The vehicle speed is greater than 1 mph.
- The manifold absolute pressure is less than 99 kPa.
- The engine speed is below 3400 rpm.
- An ABS DTC was set.

Action Taken When the DTC Sets
- The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.
- A history DTC is stored.

Conditions for Clearing the DTC
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- DTCs can be cleared by using a scan tool.

Diagnostic Aids
The setting of this DTC indicates that a misfire was detected and that the PCM could not determine if the detected misfire was true or due to operating the vehicle on a rough surface. A misfire can be a true misfire with or without setting this DTC. Check the EBCM for poor connections at the UART serial data terminals. Be sure no true misfire exists after repairing the cause of this DTC.

DTC P1380 - ABS DTC Detected Rough Road Data Unusable:

Test Description
Numbers below refer to the step numbers on the Diagnostic Table.
1. The OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored on the scan tool for later reference.
2. ABS DTCs are found by selecting Chassis on the scan tool.
4. Be careful to clear only DTCs and not the captured information stored on the scan tool. The scan tool will issue a warning if this is about to happen.
5. A DTC P1380 being reset indicates that the PCM is not receiving the correct information from the EBCM due to an ABS DTC.
6. When DTC P1380 is set, an ABS DTC should also be set.
7. Repair any condition that remains and is causing a misfire by following the table for any DTC that has set.
8. Replacement PCM must be reprogrammed. Refer to the latest Techline information for programming procedures