Pcm Code EO47, BCM-To-Pcm Data Problem: Action:

PCM clears all BCM data from PCM memory, disables A/C clutch and turns on SERVICE ENGINE SOON light.

The PCM and BCM share information through the PCM-BCM data through the Universal Asynchronous Receiver Transmitter (UART). The BCM is in control of data link and data is only transmitted at the BCM's request. Data is sent in 8 character words at a rate of 8192 characters per second.

The data from the PCM to BCM contains engine operating information. The PCM-BCM data includes CTS, RPM and injector pulse width values so that the BCM can control cooling fans, display RPM and calculate MPG display at the CCDIC. The BCM sends the PCM air conditioning status to be used idle speed control and ambient temperature use in VCC application and release decisions.

Code EO47 is set in the PCM in event of a UART failure. If fault is a current failure, PCM will not be able to communicate with the BCM and Code B334 will be displayed as current. Code EO47 is current in the PCM but cannot be sent (displayed) to BCM because of UART fault. If the UART fault is corrected, both Code EO47 and B334 will be displayed as history codes.

Code EO47 can only be displayed as an intermittent. If fault is present, Code B334 will be current. Two failures can result in a Code EO47: