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Home >> Chevrolet >> 2001 >> Cavalier LS, 2.2 4 >> Repair and Diagnosis >> External Pages >> Different car >> Section 19 (Supplemental Inflatable Restraint System) >> Diagnostic Tests >> Scan Tool Does Not Communicate With Class 2 Device >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2000 Pontiac Sunfire and 2000 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect scan tool to Data Link Connector (DLC). If scan tool powers up, go to next step. If scan tool does not power up, inspect Data Link Connector (DLC) circuits. Scan tool should receive battery power at terminal No. 16, and ground connection at terminal No. 4. Class 2 serial data signal should be received at terminal No. 2, and grounded at terminal No. 5. See Figure. When scan tool powers up, go to next step.
  2. Turn ignition on. Using scan tool, attempt to communicate with each module on class 2 serial data circuit. If scan tool communicates with any module on circuit, go to next step. If scan tool does not communicate with any module, go to step  6.
  3. Select DISPLAY DTC function for each module. If any DTCs beginning with "U" in the number range of 1000-1255 are displayed, go to next step. If no DTCs beginning with "U" are displayed, go to step  5.
  4. If DTC U1000 is the only DTC displayed, go to CLASS 2 COMMUNICATION MALFUNCTION . If DTC U1000 is not the only DTC displayed, diagnose loss of class 2 serial data communication between modules.
  5. Diagnose communication malfunction for modules which are not communicating. Go to SIR DIAGNOSTIC SYSTEM CHECK .
  6. Turn ignition off. Disconnect scan tool from Data Link Connector (DLC). Inspect DLC terminals No. 2 and 5 for poor connections. Repair connector and establish communication with control modules. If no connector problems are found, go to next step.
  7. Measure resistance between DLC terminal No. 5 and ground. If open circuit is found, repair circuit and establish communication with control module. If no open is detected, go to next step.
  8. Test Class 2 serial data circuit for an open circuit between DLC terminal No. 2 and terminal No. B7 (Purple wire) of connector C2 of BCM. If an open is found, repair circuit and establish communication with control module.
  9. Disconnect (Powertrain Control Module) PCM connector C1. Disconnect radio connector C1 (base) or C2 (Monsoon). Disconnect instrument cluster connector. Install scan tool. Turn ignition on. Using scan tool, communicate with BCM through class 2 serial data circuit. If scan tool communicates with (Body Control Module) BCM on class 2 serial data circuit, go to next step. If scan tool does not communicate with BCM, go to step  11.
  10. Turn ignition off. Disconnect Electronic Brake Control Module (EBCM) connector C1. Reconnect PCM connector C1. Turn ignition on. Using scan tool, communicate with BCM or PCM through class 2 serial data circuit. If communication was established, go to step  12. If communication was not established, go to step  13.
  11. Turn ignition off. Test class 2 serial data circuit for a short to ground or voltage between BCM and DLC, BCM and PCM, BCM and Instrument Panel Cluster (IPC), BCM and RADIO. (Turn ignition on when testing for short to voltage). If a short condition was found, correct condition and establish communication with control module. If short condition was not found, go to step  16.
  12. Turn ignition off. Disconnect SDM connector. Reconnect IPC connector. Turn ignition on. Attempt to communicate with BCM, PCM or IPC through class 2 serial data circuit. If communication is established with any module, go to step  14. If communication is not established with any module, go to step  15.
  13. Turn ignition off. Test class 2 serial data circuit between PCM and EBCM for a short to ground or voltage. (Turn ignition on when checking for voltage). If short is found, correct condition and establish communication with control module. If short is not found, go to step  17.
  14. Turn ignition off. Connect SDM connector. Turn ignition on. Attempt communication with BCM, PCM, IPC or SDM on class 2 serial data circuit. If communication is established, go to step  21. If communication is not established, go to step  19.
  15. Turn ignition off. Test class 2 serial data circuit between IPC and SDM for short to ground or short to voltage. If short was found and corrected, establish communication with control module. If no short is found, go to step  18.
  16. Inspect for poor connections at BCM harness connector. If connection problems are found, repair connections. Establish communication with control module. If no connection problems are found, go to step  24.
  17. Inspect for poor connections at PCM harness connector. If connection problems are found, repair connections. Establish communication with control module. If no connection problems are found, go to step  25.
  18. Inspect for poor connections at IPC harness connector. If connection problems are found, repair connections. Establish communication with control module. If no connection problems are found, go to step  26.
  19. Turn ignition off. Test class 2 serial data circuit between SDM and EBCM for a short to ground or voltage. (Turn ignition on when checking for short to voltage). If short was found and corrected, establish communication with control module. If no short was found, go to next step.
  20. Inspect for poor connections at SDM harness connector. If poor connections were found, correct condition and establish communication with control module. If connections were okay, go to step  27.
  21. Turn ignition off. Reconnect EBCM connector. Turn ignition on. Attempt to communicate with BCM, PCM, IPC, EBCM or SDM through class 2 serial data circuit. If communication is established, go to next step. If communication is not established, go to step  23.
  22. Inspect for poor connections at radio harness connector. If poor connections are found, correct condition and establish communication with control module. If connections were okay, go to step  29.
  23. Inspect for poor connections at EBCM connector. If poor connections are found, correct condition and establish communication with control modules. If connections were okay, go to step  30.
  24. Replace Body Control Module (BCM). Go to step  31.
  25. Replace Powertrain Control Module (PCM). Go to step  31.
  26. Replace Instrument Panel Cluster (IPC). Go to step  31.
  27. Replace Sensing & Diagnostic Module (SDM). See SENSING & DIAGNOSTIC MODULE (SDM)  under REMOVAL & INSTALLATION. Go to step  31.
  28. Replace radio. Go to step  31.
  29. Replace EBCM. Go to step  31.
  30. Reconnect all disconnected electrical connectors. Install scan tool. Turn ignition on. Wait 10 seconds. Select DISPLAY DTC function for each module. Record all displayed DTC and DTC status. If any DTCs were recorded with both a current and a "U" status, go to step  33. If any DTCs were recorded that did not have a current and a "U" status, go to next step).
  31. If any DTCs were recorded that began with "U", go to next step. If no DTCs were recorded that began with "U", go to step  33.
  32. Diagnose DTCs for each module or malfunction indicated. If vehicle will start and run, repair is complete.
  33. Using scan tool, clear all DTCs. Go to SIR DIAGNOSTIC SYSTEM CHECK .
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