Circuit Description

PCM receives rough road information from EBCM/EBTCM 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/EBTCM transmits rough road information based on inputs from wheel speed sensors. If EBCM/EBTCM 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:

• Engine load less than 87 percent.
• Engine speed less than 5000 RPM.
• Vehicle speed greater than 10 MPH.
• Misfire DTC is occurring and requesting MIL to be illuminated.
• PCM has detected an EBCM/EBTCM rough road sensing error.