Brake Signal: Description and Operation

The PCM receives rough road information from the Electronic Brake Control Module (EBCM) on the serial data circuit (CKT 800). The PCM uses the rough road information to enhance the misfire diagnostic by allowing crankshaft speed variations caused by driving on rough road surfaces. The EBCM calculates rough road information by monitoring the ABS wheel speed sensors.

If a fault occurs which causes the PCM to not receive rough road information while a misfire DTC is requesting the MIL, DTC P1381 will set.