P1381

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The PCM receives rough road information from the EBCM/EBTCM on the serial data circuit (CKT 800). The PCM uses the rough mad information to enhance the misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from variations caused by the misfires. The EBCM/EBTCM transmits rough road information based on inputs from the wheel speed sensors. If a malfunction occurs which causes the PCM to not receive rough road information while DTC P0300 is requesting the Malfunction Indicator Lamp (MIL), DTC P1381 will set.

Conditions for Setting the DTC

^ Engine load less than 87%.

^ Engine speed less than 5000 RPM.

^ Vehicle speed greater than 10 mph.

^ A misfire DTC is occurring and requesting the MIL to be illuminated.

^ The PCM has detected a rough road data error for at least 10 seconds.

Action Taken When the DTC Sets

^ DTC P1381 will not cause the PCM to illuminate the MIL. If an active misfire DTC is occurring, the misfire DTC may cause the PCM to illuminate the MIL.

^ The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

^ A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

^ DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids

Check for the following conditions:

^ Poor connection at the PCM or at the EBCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

^ Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe ABS data on the scan tool while moving connectors and wiring harnesses related to the EBCM. A loss of ABS data will indicate 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 UART serial data circuit.

4. Checks the UART serial data circuit at the EBCM/EBTCM for correct voltage.