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Scan Tool Does Not Communicate With Class 2 Device: Testing

  1. Connect scan tool to DLC. If scan tool powers up, go to next step. If scan tool does not power up, go to SCAN TOOL DOES NOT POWER UP  .
  2. Turn ignition switch to RUN position. Attempt to communicate with Powertrain Control Module (PCM), radio and remote CD player (if equipped), Electronic Brake Control Module (EBCM), Electronic Brake & Traction Control Module (EBTCM), Sensing and Diagnostic Module (SDM), Instrument Panel Cluster (IPC), Driver Information Display (DID) and Body Control Module (BCM). If scan tool communicates with any modules, go to next step. If scan tool does not communicate with any module, go to step  5 .
  3. Select DISPLAY DTCs for each module. Record each DTC, DTC status and module which stored DTC. If DTC U1300, U1301 or U1305 are stored, they should be ignored at this time. If any DTC between U1000 and U1255 exist, go to next step. If no DTCs between U1000 and U1255 exist, see check for short to power and short to ground in class 2 data bus circuits. If other DTCs exist, go to appropriate system starting point for related system.
  4. If DTC U1000 or U1255 are only DTCs displayed in range specified in step  3 , go to DTC U1000 & DTC U1255: CLASS 2 COMMUNICATION MALFUNCTION  . If DTC U1000 or U1255 are not displayed in range specified in step  3 , go to DTC U1001-U1254: LOSS OF COMMUNICATION WITH XXX  .
  5. Turn ignition switch to LOCK position. Disconnect scan tool. Inspect DLC connector terminals No. 2 (Purple wire) and No. 5 (Black wire) for poor terminal contact. Repair as necessary. Go to applicable diagnostic system check. See TROUBLE SHOOTING  . If DLC terminal contact is okay, go to next step.
  6. Check continuity between ground and DLC terminal No. 5 (Black wire). See Figure . If continuity exists, go to next step. If continuity does not exist, repair open or high resistance in Black wire. See WIRING DIAGRAMS  .
  7. Disconnect splice pack SP205. See Figure . Check for poor terminal contact at splice pack connector. Repair as necessary. Go to applicable diagnostic system check. See TROUBLE SHOOTING  . If splice pack SP205 terminal contact is okay, go to next step.
  8. Check continuity of class 2 data bus circuit (Purple wire) between DLC terminal No. 2 and SP205 terminal "A". See Figure and Figure . If continuity exists, go to next step. If continuity does not exist, repair open or high resistance in Purple wire. See WIRING DIAGRAMS  .
  9. Using proper terminal adapter from Connector Test Adapter Kit (J 35616-A), connect jumper between splice pack SP205 harness connector terminals "A" (Purple wire) and terminal "B" (Dark Green wire). See Figure . Turn ignition switch to ON position. Attempt communication with Powertrain Control Module (PCM). If scan tool communicates with PCM, go to step  11 . If scan tool does not communicate with PCM, go to next step.
  10. Turn ignition switch to LOCK position. Disconnect PCM harness connector. Check for short to ground and short to power (with ignition switch in RUN position) in class 2 serial data circuit (Purple wire) between PCM connector terminal A5 and splice pack SP205. See Figure . Repair as necessary. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repair, go to step  25 . If circuit is okay, go to step  23 .
  11. Remove jumper wire from terminal "B" and connect jumper to terminal "F" (Dark Blue wire) of SP205 connector. Turn ignition switch to ON position. Attempt communication with Sensing and Diagnostic Module (SDM). If scan tool communicates with SDM, go to step  13 . If scan tool does not communicate with SDM, go to next step.
  12. Turn ignition switch to LOCK position. Disconnect SDM harness connector. Check for short to ground and short to power (with ignition switch in RUN position) in class 2 serial data circuit (Dark Blue wire) between splice pack SP205 harness connector terminal "F" and SDM harness connector terminal A5. See Figure . Repair as necessary. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repair, go to step  25 . If circuit is okay, go to step  23 .
  13. Disconnect jumper wire from splice pack SP205 harness connector terminal "F" (Dark Blue wire) and connect jumper wire to splice pack SP205 harness connector terminal "E" (Light Blue wire). See Figure . Turn ignition switch to ON position. Attempt communication with Electronic Brake Control Module (EBCM)/Electronic Brake and Traction Control Module (EBTCM). If scan tool communicates with EBCM/EBTCM, go to step  15 . If scan tool does not communicate with EBCM/EBTCM, go to next step.
  14. Turn ignition switch to LOCK position. Disconnect EBCM/EBTCM harness connector. See Fig 1 . Check for short to ground or short to power (with ignition switch in RUN position) in class 2 serial data circuit (Light Blue wire) between splice pack SP205 harness connector terminal "E" and EBCM/EBTCM connector terminal. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. Repair as necessary. After repair, go to step  25 . If circuit is okay, go to step  23 .
  15. Disconnect jumper wire from splice pack SP205 harness connector terminal "E" (Light Blue wire) and connect jumper wire to splice pack SP205 harness connector terminal "G" (Gray wire). See Figure . Turn ignition switch to ON position. Attempt communication with Instrument Panel Cluster (IPC) module. If scan tool communicates IPC module, go to step  17 . If scan tool does not communicate with IPC module, go to next step.
  16. Turn ignition switch to LOCK position. Disconnect IPC connectors. Check for short to ground and short to power (with ignition switch in RUN position) in class 2 serial data circuit (Orange wire) between splice pack SP205 and IPC module connector. Repair as necessary. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repair, go to step  25 . If circuit is okay, go to step  23 .
  17. Disconnect jumper wire from splice pack SP205 harness connector terminal "G" (Gray wire). Connect jumper wire to splice pack SP205 harness connector terminal "M" (Purple wire). See Figure . Turn ignition switch to ON position. Attempt communication with PASS-KEY(R) III (PK3) module. If scan tool communicates with PK3 module, go to step  19 . If scan tool does not communicate with PK3 module, go to next step.
  18. Turn ignition switch to LOCK position. Disconnect PASS-Key(R) III module harness connector. Check for short to ground and short to power (with ignition switch in RUN position) in class 2 serial data circuit (Purple wire) between splice pack SP205 in-line harness connector terminal "E" and PK3 module. See Figure . Repair as necessary. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repair, go to step  25 . If circuit is okay, go to step  23 .
  19. Disconnect jumper wire from splice pack SP205 harness connector terminal "M" (Purple wire) and connect jumper wire to splice pack SP205 harness connector terminal "K" (Purple wire). See Figure . Turn ignition switch to ON position. Attempt communication with Driver Information Display (DID). If scan tool communicates with DID, go to step  22 . If scan tool does not communicate with DID, go to next step.
  20. Disconnect jumper wire from splice pack SP205 harness connector terminal "K" (Purple wire) and connect jumper wire to splice pack SP205 harness connector terminal "D" (Orange wire). See Figure . Turn ignition switch to ON position. Attempt communication with radio. If scan tool communicates with radio, go to step  24 . If scan tool does not communicate with radio, go to next step.
  21. Turn ignition switch to LOCK position. Disconnect DID harness connector. Check for short to ground and short to power (with ignition switch in RUN position) in class 2 serial data circuit (Yellow wire) between splice pack SP205 harness connector terminal "K" and DID module harness connector terminal 15. Repair as necessary. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repair, go to step  25 . If circuit is okay, go to step  23 .
  22. Turn ignition switch to LOCK position. Disconnect radio. Turn ignition switch to ON position. Check class 2 data circuit (Yellow wire) between splice pack SP205 and radio for short to ground, then check for short to voltage. Repair Yellow wire as necessary. After repairs are complete, go to  25 . If Yellow wire is okay, go to next step.
  23. Check for poor terminal contact at class 2 serial data circuit of module that is not communicating. Repair as necessary. See WIRING DIAGRAMS  . If terminal contact is okay, replace module in question. After repair, go to next step.
  24. Replace any control module that does not communicate. Go to next step.
    NOTE: In the following step, scan tool may require a power up reset before communication will occur due to a short in class 2 serial data circuit. Ensure scan tool is off or is disconnected before performing test.
  25. Reconnect all disconnected connectors and components. Install scan tool to DLC. Turn ignition switch to ON position. Wait 10 seconds. Select DISPLAY DTCs function for each module. Record and any loss of communication DTCs exist ("U" type DTCs) and DTC status. If no communication DTCs exist, go to next step. If any loss of communication DTCs exist and are current, go to appropriate DIAGNOSTIC TEST  in SELF-DIAGNOSTIC SYSTEM.
    Fig 1: Locating Electronic Brake Control Module (EBCM) Or Electronic Brake & Traction Control Module (EBTCM)
    G97C03504Courtesy of GENERAL MOTORS CORP.
    Fig 2: Identifying Driver Information Center (DIC) Harness Connector
    G00009285Courtesy of GENERAL MOTORS CORP.
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