Test C: Scan Tool Does Not Communicate With UART Data Line
- Connect scan tool to Data Link Connector (DLC). DLC is located below instrument panel, right of steering column. See Figure . If scan tool powers up, go to next step. If scan tool does not power up, go to TEST A: SCAN TOOL DOES NOT POWER UP .
- Turn ignition switch to RUN position. Attempt to communicate with each module on UART data line circuit. If all modules on UART data line do not communicate with scan tool, go to next step. If any module on UART data line communicates with scan tool, go to step 4 .
- Check for open in UART data line circuit (Tan wire) between PCM harness connector C1 terminal No. 15 and DLC terminal No. 9. If Tan wire is okay, go to next step. If Tan wire is open, repair as necessary. Perform appropriate diagnostic system check.
- Turn ignition switch to OFF position. Disconnect scan tool. Disconnect all modules on UART data line circuit. Check for short to ground or short to voltage (with ignition switch in RUN position) in UART data line circuits (Tan wires) between DLC and appropriate module(s). If UART data line circuit is okay, go to next step. If short to ground or short to voltage exist, repair as necessary. Perform appropriate diagnostic system check.
- Turn ignition switch to OFF position. Disconnect scan tool from DLC. Check DLC terminals No. 5 (Tan wire) and No. 9 (Black wire) for poor terminal contact and pushed out pins. If terminals are okay, go to next step. If terminals are not okay, repair as necessary. Perform appropriate diagnostic system check.
- Replace module(s) that did not communicate over UART data line. Perform appropriate set up procedure for module if required. Perform appropriate diagnostic system check.