Circuit Description

PCM receives rough road information from the Electronic Brake Control Module (EBCM) on the serial data circuit. PCM uses this information to enhance the misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from variations caused by true misfires. EBCM transmits rough road information based on inputs from wheel speed sensors. If EBCM detects a condition which will allow it to properly identify rough road situations while a misfire condition is being detected by the PCM, DTC will set.

Conditions for setting DTC are: engine load is less than 87 percent, engine speed is less than 5000 RPM, vehicle speed is greater than 10 MPH, misfire DTC is occurring and requesting MIL to be illuminated and PCM has detected an EBCM rough road sensing error.