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Test B: Scan Tool Does Not Communicate With Class 2 Device: Testing

  1. Connect scan tool to Data Link Connector. See Figure. If scan tool powers up, go to next step. If scan tool does not power up, see TEST A: SCAN TOOL DOES NOT POWER UP .
  2. Turn ignition on. Try to communicate with each module on class 2 serial data line. If using a Tech 2, use CLASS 2 MESSAGE MONITOR feature. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any modules along class 2 serial data line, go to step  8.
  3. Using scan tool select display DTC function for each module. If using a Tech 2, use the CLASS 2 DTC CHECK feature to determine which modules have set DTCs. Record all DTCs, DTC status and module which DTC is set. If any DTCs between U1000 and U1305 are set, go to next step. If no DTCs between U1000 and U1305 are set, go to step  7.
  4. If DTC U1300, U1301 or U1305 are set, go to next step. If DTC U1300 and U1301 or U1305 are not set, go to step  6.
  5. Turn ignition on. Use DMM MIN/MAX function to capture intermittent conditions. Test Purple wire at affected module for a short to ground or a short to voltage. If no problem was found, go to next step. If a problem was found and corrected, go to step  18.
  6. If U1000 and U1255 are the only DTCs set in step  4, go to DTC U1000 & DTC U1255: CLASS 2 COMMUNICATION MALFUNCTION . If U1000 and U1255 are not the only DTCs set in previously specified range, see DTC U1001-U1254 LOSS OF COMMUNICATIONS WITH XXX .
  7. Diagnose non communicating module. See DTC U1001-U1254 LOSS OF COMMUNICATIONS WITH XXX  under DIAGNOSTIC TESTS for module which is not communicating. Perform appropriate diagnostic system check under DIAGNOSTIC SYSTEM CHECKS .
  8. Turn ignition off. Disconnect scan tool. Check for loose wires and poor connections at DLC. If no problem was found, go to next step. If a problem was found and corrected, perform appropriate diagnostic system check under DIAGNOSTIC SYSTEM CHECKS .
  9. Check for an open or high resistance in Black wire between DLC terminal No. 4 and ground located at passenger's front door jamb. Check for an open or high resistance in Black/White wire between DLC terminal No. 5 and driver's front door jamb. If no problems were found, go to next step. If a problem was found and corrected, perform appropriate diagnostic system check under DIAGNOSTIC SYSTEM CHECKS .
  10. Check Purple wire for high resistance, open short to ground or short to voltage between DLC terminal No. 2 and Instrument Panel Cluster (IPC) harness connector C2 terminal B8 and between DLC and PCM harness connector C1 terminal No. 59. If no problem was found, go to next step. If problem was found and corrected, perform appropriate diagnostic system check under DIAGNOSTIC SYSTEM CHECKS .
  11. Turn ignition off. Open communication loop by disconnecting either IPC harness connector C2 or PCM harness connector C1 terminal. Leave one of the harness connectors connected. Turn ignition on. Try to communicate with modules still connected to DLC. If scan tool will not communicate with modules still connected, go to next step. If scan tool will communicate with modules still connected, go to step  13.
  12. The communication fault is located in the communication line that is still connected to the DLC. Turn ignition off. Disconnect the furthest module from DLC and try to restore communications. Turn ignition on. If communications are not restored, try the next closest module in the line and continue until communication is restored. If communication is not restored, go to next step. If communication was restored, go to step  15.
  13. The communication fault is located in the communication line that is not connected to the DLC. Disconnect the furthest module from DLC and try to restore communications. If communications are not restored, try the next closest module in the line and continue until communication is restored. If communication is not restored, go to next step. If communication was restored, go to step  18.
  14. Repair class 2 serial data circuits and connectors to last module connected to DLC. After repair, go to step  18.
  15. Check for short to ground in connectors to last module in serial data line from DLC being tested. Turn ignition on. Check for short to voltage in connectors to last module in line from DLC being tested. See WIRING DIAGRAMS . If no problem was found, go to next step. If a problem was found and corrected, go to step  18.
  16. Check for loose wires and poor connections to last module disconnected. If no problem was found, go to next step. If a problem was found and corrected, go to step  18.
  17. Remove last module disconnected and program is required. See appropriate module under REMOVAL & INSTALLATION . Go to step  18.
  18. Connect all connectors and all modules. Connect scan tool. Turn ignition on. Wait 10 seconds and select display DTCs function for each module. Use CLASS 2 DTC CHECK feature in order to determine which modules have set DTCs. Record all set DTCs and DTC status. If any current DTCs that start with letter "U" are set, go to step  20. If no current DTCs that start with "U" are set, go to next step.
  19. If any DTCs which do not begin with a letter "U" is set, go to next step. If any DTCs which do not begin with a letter "U" are set, go to step  21.
  20. Perform diagnostic procedure for DTCs set. Go to next step.
  21. If any DTCs still exist, return to step  20. If DTCs do not exist, go to next step.
  22. Clear DTCs using scan tool. System is okay at this time.
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