E047

Wiring Diagram.:

DESCRIPTION:

The PCM/ECM and BCM share information through the Universal Asynchronous Receiver Transmitter (UART) data link. The BCM is the "Master" of the link and data is only transmitted at the BCM's request. Data is sent in eight-character "Words" at the rate of 8192 characters per second. The data from the PCM/ECM to the BCM contains engine operation information. The PCM/ECM-BCM data also includes Coolant Temperature Sensor, Engine Speed and injector pulse width values, so the BCM can control cooling fans, display engine speed and calculate MPG for display at the driver information center. The BCM sends the PCM/ECM air conditioning status to be used for idle speed control and ambient (outside) temperature for use in VCC apply and release decisions.

Code E047 is logged in the PCM/ECM in the event of a UART fault. If the fault is a hard failure, the PCM/ECM will not be able to communicate with the BCM and code B334 will be displayed as current. Code E047 is current in the PCM/ECM but can't be sent to the BCM because of the UART fault. If the UART fault is corrected, both code E047 and code B334 will be displayed as history codes.

TEST CONDITIONS:

1. Code EO12 clear.
2. Ignition ON.
3. Engine speed 500 rpm or greater for 20 seconds.

FAILURE CONDITIONS:

PCM/ECM receives bad data or no data from the BCM for 3 seconds.

ACTION TAKEN:

1. PCM/ECM clears all BCM data from PCM/ECM memory.
2. PCM/ECM disables the A/C clutch.
3. PCM/ECM turns on "SERVICE ENGINE SOON" telltale.

NOTE ON INTERMITTENTS:

Code E047 should be diagnosed using the chart for BCM code B334.

Code E047 can only be displayed as an intermittent. If the fault is present, code B334 will be current, diagnose using code B334.

These failures will result in a code E047 stored as history:

1. Both circuits 800E and 800F from the PCM/ECM to BCM open.

Symptoms will be:

a. "SYSTEM FAULT" message on CCDIC.
b. "ENGINE CONTROL SYSTEM" (ECS) and "CHECK INFO CENTER" lights on.
c. Diagnostics entered "NO PCM/ECM DATA" is displayed on CCDIC.
d. When repaired, E047 and B334 will be history codes.

2. Circuit 800 shorted to ground at any point.

Symptoms will be:

a. "SYSTEM FAULT" message on CCDIC.
b. "ENGINE CONTROL SYSTEM" light is on.
c. Instrument panel gauges will flash.
d. Climate control goes blank.
e. Engine cooling fans go to high.
f. Diagnostics cannot be entered, CCDIC stays at "SYSTEM FAULT".
g. When repaired, it will show E047, B334, B335, B336, B337 history codes.

WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETED, CLEAR CODES AND VERIFY OPERATION