P1381

Circuit Description
The PCM receives rough road information from the EBCM / EBTCM on the Class 2 serial data circuit. The PCM uses The rough road information 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 / EBTCM transmits rough road information based on inputs from the wheel speed sensors. If a loss of communication occurs which causes the PCM not to receive rough road information while DTC P0300 is requesting the MIL, DTC P1381 will set.

Conditions for Running the DTC
^ Engine load is less than 87 percent.
^ Engine speed is less than 5000 RPM.
^ Vehicle speed is greater than 10 mph.
^ A misfire DTC is occurring and requesting the MIL to be illuminated.

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

Action Taken When the DTC Sets
^ The PCM stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

Conditions for Clearing the MIL/DTC
^ A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any Other non-emission related diagnostic.
^ A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
^ Use a scan tool in order to clear the MIL/DTC.
^ Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended.

Diagnostic Aids

Notice: Use the Connector Test Adapter kit J 35616-A for any test that requires probing the following items:
^ The PCM harness connectors
^ The electrical center fuse/relay cavities
^ The component terminals
^ The component harness connector
Using this kit will prevent damage caused by the improper probing of connector terminals.
Check for the following conditions:
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to 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.