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Test B: Scan Tool Does Not Communicate With Universal Asynchronous Receive & Transmit Data Line

NOTE: This diagnostic test is for communication between scan tool and Powertrain Control Module (PCM). For Electronic Brake Control Module (EBCM) and Sensing and Diagnostic Module (SDM) communication diagnostics, see TEST A: SCAN TOOL DOES NOT COMMUNICATE WITH COMPONENTS  .
  1. If data link communications system check has been performed, go to next step. If data link communications system check has not been performed, perform data link communications system check. Perform DATA LINK DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Connect scan tool to Data Link Connector (DLC). DLC is located under left side of instrument panel, right of steering column. Attempt to communicate with same system on a different vehicle. If communication is established, go to next step. If communication is not established, go to step  4 .
  3. Turn ignition switch to LOCK position. Inspect scan tool, cable connector and DLC for proper connection. If scan tool cable connector and DLC are okay, go to step  5 . If scan tool cable connector or DLC are not okay, go to step  6 .
  4. Scan tool may be defective. Use scan tool manufacturer's manual to diagnose scan tool. After repair, perform DATA LINK DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  5. Measure resistance between terminals No. 5 (Black wire) and No. 7 (Purple/White wire) at DLC. If resistance is 2 ohms or more, go to step  7 . If resistance is less than 2 ohms, go to step  8 .
  6. Repair DLC, scan tool or cable as necessary. After repair, perform DATA LINK DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  7. Measure voltage between terminals No. 5 (Black wire) and No. 7 (Purple/White wire) at DLC. If voltage does not exist, go to step  9 . If any voltage exists, go to step  10 .
  8. Repair short to ground in Purple/White wire between Powertrain Control Module (PCM) and DLC. See DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repair, perform DATA LINK DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  9. Measure voltage between ground and DLC terminal No. 16. See Figure . If battery voltage exists, go to step  11 . If battery voltage does not exist, go to step  12 .
  10. Repair short to voltage in Purple/White wire between Powertrain Control Module (PCM) and DLC. See DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repair, perform DATA LINK DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  11. Check for open in Purple/White wire between Powertrain Control Module (PCM) and DLC. See DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repair, perform DATA LINK DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. If Purple/White wire is okay, diagnose engine controls concern. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  12. Repair open in White wire between junction block and DLC. See Figure . After repair, perform DATA LINK DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
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