Code I034 Loss Of PCM Data

If this code is set with Codes I033, I037, P047 and A037, see MULTIPLE DATA COMMUNICATION CODES. If this code is set by itself, IPC is not able to exchange data with PCM. Problem will be one of following:
- An open in Tan wire circuit between IPC and PCM, and a second open between PCM and ACP.
- An open in PCM power or ground circuits. This will also set a Code P052.
- A faulty PCM or PCM CAL-PAK. CAL-PAK is located inside PCM. PCM is located behind glove box, at top of right kick panel.
Start engine. If engine does not start or there is serious driveability complaint, go to appropriate G - TEST W/CODES article in ENGINE PERFORMANCE. If engine starts, turn engine off. Turn ignition on. Enter self-diagnostics. See ENTERING SELF-DIAGNOSTICS under SELF-DIAGNOSTICS.
If Code I034 sets as a current code (I034C), go to next step. If Code I034 sets as a history code (I034H), check for Code P052(H). If Code P052H is also set, proceed to G - TEST W/CODES article in ENGINE PERFORMANCE. If P052H is not set, there is an intermittent problem. Check for an open in Tan wire circuit between IPC and PCM.
Disconnect PCM connector C2 (middle one). Using DVOM, measure voltage at PCM harness connector C2, terminal C12 (4.6L) or terminal A8 (4.9L). See Figure or Figure . If voltage is not fluctuating between 3 and 5 volts, repair open or short in Tan wire circuit between IPC and PCM.
If voltage is fluctuating between 3 and 5 volts, ensure terminals and connections are not damaged and that connectors fully seat into PCM. Ensure CAL-PAK is properly installed into PCM and that CAL-PAK pins are fully seated into PCM.
If all connections are good and CAL-PAK is properly installed, check for high resistance is PCM ground circuits. Repair as necessary. If ground circuits are okay, replace faulty PCM. After all repairs are completed, clear all codes and verify correct operation.