Part One

Diagnostic Chart:

Wiring Diagram:

The IPC controls the communication line between the vehicle's computer systems. If loss of communication occurs with two or more components, a fault in the communication line is suspect. This trouble tree should be utilized when multiple data communication codes are present.

TEST DESCRIPTION

Test numbers refer to circled numbers on the diagnostic chart.

1. If I033, I034 and I037 are set, the IPC has lost communication with the entire data line. Codes P047 (PCM Loss of IPC Data) & I037 (Air Conditioning Programmer (ACP) Loss of IPC Data) should also set, but since the IPC can't communicate with these devices, these codes can only be displayed as History.

2. If Codes I047 (PCM Loss of IPC Data) & I037 (ACP Loss of IPC Data) are set, then two components were unable to communicate with the IPC. The most likely cause of this would be an intermittent IPC loss of power, which could also store Code I052. Following I052 diagnosis will verify IPC power and ground circuits.

3. If Codes I033 & I037 are set (A037 may also set) the IPC has lost communication with the Sensing and Diagnostic Module (SDM) and the ACP, while still communicating with the PCM. This indicates that there are two opens in the data line isolating the SDM and ACP from the IPC. Repairing one or both of these opens will provide a path for communication with the IPC. If Codes I034 & I037 are set (P047 & A037 may also set) the IPC has lost communication with the PCM and the ACP, while still communicating with the SDM. This indicates that there are two opens in the data line isolating the PCM and ACP from the IPC. Repairing one or both of these opens will provide a path for communication with the IPC.

4. If the PCM losses power Codes P052 and I034 will set. Diagnose per loss of PCM power, P052 COMPUTERS AND CONTROL SYSTEMS. If the IPC losses communications with the PCM I034, the PCM should also lose communication with the IPC P047. Diagnose this as one data problem per I034 trouble tree. If the IPC losses communications with the ACP I037, the ACP should also lose communication with the IPC A037. Diagnose this as one data problem per 1037 trouble tree. Computers and Control Systems

5. The expected voltage for the data line is 3 to 5 volts with constant fluctuation. If this voltage is not correct, this tree will isolate the failure to a specific component or section of the 800 circuit.

NOTES ON INTERMITTENTS

Codes A037, P047, and P052 may set with data line codes but will only be visible as history codes.