Scan Tool Does Not Communicate with UART Device

SCAN TOOL DOES NOT COMMUNICATE WITH UART DEVICE

CIRCUIT DESCRIPTION
The UART protocol utilizes a single wire bi-directional data line used to exchange information between the modules.

The following modules are connected to the serial data circuit:
- Powertrain interface module (PIM)
- Body control module (BCM)
- Instrument panel cluster (IPC)
- Electronic brake control module (EBCM)
- Sensing and diagnostic module (SDM)
- Radio

TEST

Steps 1-6:

Step 7: