EBTCM / EBCM - PCM Class 2 Serial Data

The PCM uses the Class II serial data line to communicate with various other components and systems within the vehicle. The PCM ensures that communication remains established by monitoring state of health messages from the other devices using the circuit. If the PCM detects a loss of the state of health serial data message from the Electronic Brake Control Module (EBCM), the PCM stores DTC P1602. The EBCM disables traction control, set an ABS/TCS DTC, and illuminates the TRACTION OFF lamp.

The PCM also receives rough road information from the EBCM on the Class II serial data circuit. The PCM uses the rough road information in order to enhance the misfire diagnostic by detecting crankshaft speed variations caused by driving on rough road surfaces. This allows the PCM to reject false misfire information. The EBCM calculates rough road information by monitoring the ABS wheel speed sensors. If a malfunction occurs which does not allow the EBCM to transmit correct rough road information to the PCM while a misfire DTC is requesting the malfunction indicator lamp (MIL), DTC P1380 is set. If a loss of communications occurs which causes the PCM to not receive rough road information while a misfire DTC is requesting the MIL, DTC P1381 is set.