I003

CIRCUIT DESCRIPTION

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 I032, I033, I034 I037 and I039 are set, the IPC has lost communication with the entire data line. Codes P047 (PCM Loss of IPC Data), I037 (ACP Loss of IPC Data) and T072 (Traction Control Loss of Serial 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 P047 (PCM Loss of IPC Data) & I037 (ACP Loss of IPC Data), T072 (Traction Loss of Serial 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 Diagnostic Energy Reserve Module (DERM) and the ACP, while still communicating with the PCM. This indicates that there are two opens in the data line isolating the DERM 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 DERM. 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. 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 I037 trouble tree.

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.

6. With IPC and DERM disconnected, resistance from "C1" to ground should be infinite. If not, repair short to ground in CKT 800.

7. With DERM "A8" grounded, IPC should see no resistance to ground at "C1."

8. A single open in CKT 800 will not cause the codes to set. A second open will also be present between the IPC and the PCM. Repairing either will return the system to normal functioning mode.

9. With the IPC and PCM disconnected, resistance from "C2" to ground should be infinite. If not, repair short to ground in CKT 800.

10. Jumpering the cavities completes the circuit without the DERM. If proper voltage is now seen, the problem was with the DERM. Otherwise the 800 circuit is at fault.

NOTES ON INTERMITTENTS

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