Code P047, Pcm/IPC Data Problem: Notes

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

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

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 IPC Code IO34 will be displayed as current. Code P047 is current in PCM but cannot be sent (displayed) to IPC because of UART fault. If UART fault is corrected, both Codes P047 and IO34 will be displayed as history codes.

Code P047 should be diagnosed using chart for IPC Code IO34. Diagnose instrument panel cluster. Refer to appropriate repair article.

Code P047 stored as history can indicate 2 failures:

Open in circuit No. 800. Symptoms will be:

1. - SYSTEM FAULT message on DIC.
2. - MIL and CHECK INFO CENTER indicators on.
3. - Diagnostics entered; NO PCM DATA displayed on DIC.
4. - When fault is repaired, Codes P047 and IO34 will show as history codes.

Short to ground in circuit No. 800 at any point. Symptoms will be:

1. - SYSTEM FAULT message on DIC.
2. - SERVICE VEHICLE SOON indicator on.
3. - Instrument panel gauges flash.
4. - Climate control panel goes blank.
5. - Engine cooling fans go on high speed.
6. - Diagnostics disabled; SYSTEM FAULT message stays on DIC.
7. - When fault is repaired, Codes P047, IO33, IO34 and IO37 will show as history codes.