P1381

DTC P1381 ABS Rough Road Class 2 Serial Data Fault




Circuit Description
The PCM identifies an engine misfire by detecting the variations in crankshaft speed. The crankshaft speed variations can also occur when a vehicle is operated over a rough surface. The ABS (Anti-Lock Brake System) can detect when the vehicle is on a rough surface based on the wheel acceleration/deceleration data supplied by each wheel speed sensor. The EBCM (Electronic Brake Control Module) over the Class 2 serial data line sends this information to the PCM. The PCM then uses this information in order to determine if the crankshaft variations are being caused by an actual engine misfire or from being driven on a rough surface. DTC P1381 is a type D code.

Conditions for Setting the DTC
- A DTC P0300-P0304 has been set.
- The vehicle speed is greater than 1 mph (2 km/h).
- The Manifold Absolute Pressure (MAP) is below 99.7 kPa.
- The engine speed is below 3406 RPM.
- The PCM has not received any ABS information for 2.5 seconds.

Action Taken When the DTC Sets
- The PCM records the operating conditions at the time the diagnostic fails. The Failure Records buffers stores this information.
- A history DTC is stored.
- The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

Conditions for Clearing the DTC
- A history DTC clears after 40 consecutive warm up cycles without a fault.
- The Tech 2 can clear the DTC.

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 Class 2 serial data terminals. Be sure no true misfire exists after repairing the cause of this DTC.

Steps 1 - 8:

Steps 9 - 10:

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart:
1. The Powertrain OBD System Check 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 poop connections at the Class 2 serial data terminals. Be sure no true misfire exists after repairing the cause of this DTC.
3. Refer to the Anti-lock Brake System portion of the service manual for ABS DTCs and repairs. Performing the ABS Diagnostic System Check is the first step in diagnosing a serial data problem.
4. Be careful to clear only DTCs and not the captured information stored on the Tech 2. The Tech 2 will issue a warning if this is about to happen.
5. A DTC P1381 being reset indicates that the PCM is not receiving serial data from the EBCM due to a EBCM problem.
6. When DTC P1381 is set, ABS serial data should not be able to be displayed.
7. Repair any condition that is causing a misfire by following the table for any DTC that has set.
10. Replacement PCMs must be reprogrammed. Refer to Powertrain Control Module (PCM) in On-Vehicle Service for procedures.