EBTCM/EBCM - PCM Class 2 Serial Data

The PCM uses the Class 2 serial data line to communicate with various other components and systems within the vehicle. The PCM ensures that communication remains established by monitoring the Class 2 serial data circuit for State Of Health (SOH) messages from the other devices using the circuit. If the PCM detects a loss of the SOH serial data message from the Electronic Brake And Traction Control Module (EBTCM), the PCM stores DTC P1602.

The PCM also receives rough road information from the EBTCM on the Class 2 serial data circuit. The PCM uses the rough road information in order to enhance the misfire diagnostic by detecting any crankshaft speed variations caused by driving on rough roads. This allows false misfire information to be rejected. The EBTCM calculates the rough road information by monitoring the ABS wheel speed sensors. If a malfunction occurs which does not allow the EBTCM to transmit the correct rough road information to the PCM while a misfire DTC is requesting the MIL, DTC P1380 sets. If a loss of communications causes the PCM to not receive the rough road information while a misfire DTC is requesting the MIL, DTC P1381 sets.

Under certain conditions, the PCM has the ability to command the EBTCM to shut off the traction control via the Class 2 serial line. The following DTCs cause the traction control to be disabled, an ABS/TCS DTC to set, and the traction OFF lamp to illuminate:
^ DTC P0101 - Mass Air Flow System Performance
^ DTC P0102 - Mass Air Flow Sensor Circuit Low Frequency
^ DTC P0103 - Mass Air Flow Sensor Circuit High Frequency
^ DTC P0171 - Fuel Trim System Lean
^ DTC P0172 - Fuel Trim System Rich
^ DTC P0200 - 206 Injector Control Circuit
^ DTC P0300 - Engine Misfire Detected
^ DTC P0336 - 18x Reference Signal Circuit
^ DTC P0341 - Camshaft Position Sensor Performance
^ DTC P1374 - 3X Reference Circuit