P1381

Circuit Description
The powertrain control module (PCM) receives rough road information from the EBCM on the Class 2 serial data circuit. The PCM uses the rough road information in order to enhance the misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from variations caused by true misfires. The EBCM transmits rough road information based on inputs from the wheel speed sensors. If a loss of communication occurs which causes the PCM to not receive rough road information while DTC P0300 is requesting the malfunction indicator lamp (MIL), DTC P1381 is set.

Conditions for Running the DTC
^ The engine load is less than 87%.
^ The engine speed is less than 5000 RPM.
^ The vehicle speed is more than 10 mph.
^ A misfire DTC is occurring and requesting that the MIL be illuminated.

Conditions for Setting the DTC
The PCM is detecting a loss of communication with the EBCM for at least 10 seconds.

Action Taken When the DTC Sets
The PCM stores the conditions which were present when the DTC set as Fail Records data only.

Conditions for Clearing the MIL/DTC
^ A history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
^ DTC may be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids
Inspect for the following conditions:
^ A faulty connection at the PCM or at the EBCM. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections.
^ Inspect the wiring harness for damage. If the harness appears to be OK, observe ABS Data on the scan tool while moving the connectors and wiring harnesses related to the EBCM. A loss of ABS data indicates the location of the malfunction.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
2. Ensures that the EBCM/EBTCM is capable of transmitting serial data on the Class 2 serial data circuit.
4. Checks the Class 2 serial data circuit at the EBCM/EBTCM for correct voltage.