Part Two

Diagnostic Chart:

Wiring Diagram:

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 is the continuation of the previous page. At this point all communication codes are stored current and voltage reading at Assembly Line Data Link (ALDL) Cavity "M" shows incorrect voltage with PCM disconnected. The fault is therefore between the ALDL connector pin M and the PCM Cavity "2A8".

TEST DESCRIPTION

Test numbers refer to circled numbers on the diagnostic chart.

1. With IPC and Sensing and Diagnostic Module (SDM) disconnected, resistance from "C1" to ground should be infinite. If not, repair short to ground in CKT 800.

2. With SDM "A8" grounded, IPC should see no resistance to ground at "C1".

3. 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.

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

5. Jumpering the cavities completes the circuit without the SDM. If proper voltage is now seen, the problem was with the SDM. 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.