Pcm Code P047 - IPC-To-Pcm Data Problem: Description

PCM and IPC share information through Universal Asynchronous Receiver Transmitter (UART). IPC is master link and data are only transmitted at IPC request. Data are sent in 8-character blocks at a rate of 8192 characters per second.

Data from PCM to IPC contain engine operating information. PCM-IPC data include CTS, RPM and injector pulse width values so IPC can control cooling fans, display RPM and calculate MPG for display at Driver Information Center (DIC) panel. IPC sends PCM air conditioning status to be used for idle speed control and ambient temperature for use in TCC application and release decisions.

PCM Code P047 is set in PCM in event of a UART failure. If fault is a current failure, PCM will not be able to communicate with IPC and PCM Code IO34 will be displayed as current. PCM Code P047 is current in PCM but cannot be sent (displayed) to IPC because of UART fault. If UART fault is corrected, both PCM Code P047 and IO34 will be displayed as history codes.

PCM Code P047 should be diagnosed using chart for IPC Code IO34. Refer to appropriate INSTRUMENT PANEL article in the ACCESSORIES/SAFETY EQUIPMENT Section.

PCM Code P047 stored as history can indicate 2 failures:

• Open in circuit No. 800. Symptoms will be: A - SYSTEM FAULT message on DIC panel. B - SERVICE ENGINE SOON and CHECK INFO CENTER lights on. C - Diagnostics entered; NO PCM DATA displayed on DIC panel. D - When fault is repaired, PCM Codes P047 and IO34 show as history codes.
• Grounded circuit No. 800 at any point. Symptoms will be: A - SYSTEM FAULT message on DIC panel. B - SERVICE ENGINE SOON light on. C - Instrument panel gauges flash. D - Climate control panel goes blank. E - Engine cooling fans go on high speed. E - Diagnostics disabled; SYSTEM FAULT message stays on DIC panel. F - When fault is repaired, diagnostics show PCM Codes P047, IO33, IO34 and IO37 as history codes.