P1381

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) receives rough road information from the Electronic Brake Control Module (EBCM) on the 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 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 Malfunction Indicator Lamp (MIL), DTC P1381 will set.

CONDITIONS FOR RUNNING THE DTC
^ The engine load is less than 87 percent.
^ The engine speed is less than 5,000 RPM.
^ The vehicle speed is greater than 16km/h (10mph).
^ A misfire DTC is occurring and is requesting the MIL to be illuminated.

CONDITIONS FOR SETTING THE DTC
The PCM is detecting a loss of communication with the EBCM for at least 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The control module stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
^ The driver information center, if equipped, may display a message.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC "Last Test Failed" clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Use a scan tool in order to clear the DTC.

DIAGNOSTIC AIDS
If the condition is intermittent, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-7:

The numbers below refer to the step numbers on the diagnostic table.
2. This step ensures that the EBCM is capable of transmitting serial data on the serial data circuit.
4. Test the serial data circuit at the EBCM for correct voltage.