PCM Messages Not Received - Amplifier

Test 1 - 3:

SYMPTOM
PCM MESSAGES NOT RECEIVED - AMPLIFIER

WHEN MONITORED
With the ignition in run.

SET CONDITION
The module does not receive any messages from the PCM.

POSSIBLE CAUSES
- PCM messages not received
- Attempt to communicate with the PCM
- PCI BUS circuit open
- Powertrain control module