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Test A: Scan Tool Does Not Communicate With Class 2 Device

  1. Connect scan tool to Data Link Connector (DLC). See Figure . DLC is located under left side of instrument panel. If scan tool powers up, go to next step. If scan tool does not power up, go to TEST B: SCAN TOOL DOES NOT POWER UP  .
  2. Turn ignition switch to ON position. Attempt to communicate with all control modules on class 2 serial data circuit. See DATA LINK CONNECTORS article in WIRING DIAGRAMS. If any modules communicate with scan tool, go to next step. If no modules communicate with scan tool, go to step  5 .
  3. Using scan tool, select DISPLAY DTCS for each module. Record each DTC status (history or current) and which module set the DTC. If any communication DTCs (DTCs with "U" prefix) exist, go to next step. If no communication DTCs exist, check for intermittent or poor connections.
  4. For diagnosis and repair of "U" prefix DTC, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  .
  5. Turn ignition switch to OFF position. Disconnect scan tool from DLC. Check DLC terminals No. 2 (Purple wire) and No. 5 (Black/White wire) for proper contact. If no problem is found, go to next step. If any looseness or damage exists, repair as necessary. After repair, go to step  16 .
  6. Check for open in Black/White wire between DLC terminal No. 5 and ground. Ground point is located on front of engine, near starter. See GROUND DISTRIBUTION article in WIRING DIAGRAMS. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, go to step  16 .
  7. Disconnect left instrument panel junction block Brown 68-pin harness connector C1. Disconnect radio Black 24-pin harness connector. Check for open, high resistance, short to ground or short to voltage in Purple wire between DLC terminal No. 2 and left instrument panel junction block harness connector C1 terminal D2. See Figure . If Purple wire is okay, go to next step. If Purple wire is not okay, repair as necessary. After repair, go to step  16 .
  8. Check left instrument panel junction block harness connector C1 for poor connections or damaged terminals. See Figure . If no problem is found, go to next step. If poor connection is found, repair as necessary. After repair, go to step  16 .
  9. Turn ignition switch to OFF position. Reconnect left instrument panel junction block harness connector C1. Reconnect radio harness connector. Disconnect Electronic Brake Control Module (EBCM) Black 37-pin harness connector. EBCM is located inside left fender on brake pressure modulator valve. Connect scan tool to DLC. Turn ignition switch to ON position. Attempt to communicate with all control modules on class 2 serial data circuit. If no modules communicate with scan tool, go to next step. If any modules communicate with scan tool, go to step  15 .
  10. Turn ignition switch to OFF position. Disconnect PCM Blue 80-pin harness connector. PCM is located under left side of instrument panel, near steering column. Turn ignition switch to ON position. Attempt to communicate with all control modules on class 2 serial data circuit. If no modules communicate with scan tool, go to next step. If any modules communicate with scan tool, go to step  15 .
  11. Turn ignition switch to OFF position. Disconnect BCM Pink 24-pin harness connector C3. See Figure . BCM is located under right side of instrument panel. See Figure . Turn ignition switch to ON position. Attempt to communicate with all control modules on class 2 serial data circuit. If no modules communicate with scan tool, go to next step. If any modules communicate with scan tool, go to step  15 .
  12. Turn ignition switch to OFF position. Disconnect radio Black 24-pin harness connector. Turn ignition switch to ON position. Attempt to communicate with all control modules on class 2 serial data circuit. If no modules communicate with scan tool, go to next step. If any modules communicate with scan tool, go to step  15 .
  13. Turn ignition switch to OFF position. Reconnect EBCM harness connector. Disconnect Sensing and Diagnostic Module (SDM) 18-pin natural harness connector. SDM is located under front passenger's seat. Turn ignition switch to ON position. Attempt to communicate with all control modules on class 2 serial data circuit. If no modules communicate with scan tool, go to next step. If any modules communicate with scan tool, go to step  15 .
  14. Disconnect EBCM harness connector. Disconnect left instrument panel junction block harness connector C1. Check for high resistance, short to ground or short to voltage in class 2 serial data circuit (Purple wire). See DATA LINK CONNECTORS article in WIRING DIAGRAMS. If Purple wire is okay, go to next step. If Purple wire is not okay, repair as necessary. After repair, go to step  16 .
  15. Turn ignition switch to OFF position. Disconnect scan tool. Replace module that was last disconnected. See appropriate article for replacement and programming information. Go to next step.
  16. Reconnect all components and harness connectors. Connect scan tool to DLC. Turn ignition switch to ON position. If scan tool does not communicate, disconnect scan tool , then reconnect to reset communication. Attempt to communicate with all control modules on class 2 serial data circuit. If scan tool communicates with all modules, go to next step. If scan tool does not communicate with all modules, go to step  5 .
  17. Using scan tool, select DISPLAY DTCS for each module on class 2 serial data circuit. Record each DTC status (history or current) and which module set the DTC. If any current communication DTCs (DTCs with "U" prefix) exist, go to step  20 . If no current communication DTCs exist, go to next step.
  18. If any non-communication DTCs (DTCs without "U" prefix) were recorded, go to next step. If no non-communication DTCs (DTCs without "U" prefix) were recorded, go to step  21 .
  19. Perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . Go to next step.
  20. If all DTCs have been diagnosed, go to next step. If not all DTCs have been diagnosed, go to step  19 .
  21. Reconnect all disconnected components and connectors. Using scan tool, clear DTCs.
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