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 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 for at least 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The MIL does not turn ON.
^ A DTC is stored in memory under history DTC.
^ The Failure Records are stored.
^ The Failure Records are updated after the first failure of each ignition cycle.
^ Some type C DTCs may also cause an auxiliary service lamp to be illuminated, and/or display a message to the vehicle operator.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The history DTC will clear if the fault conditions have not been detected for 40 warm-up cycles.
^ A scan tool can be used to clear DTC information.

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.