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Scan Tool Does Not Communicate With Class 2 Device

CAUTION: Body Control Module (BCM) Pink 24-pin connector C3 contains power and ground sources. When removing BCM, always disconnect connector C3 first before disconnecting connectors C1 and C2. When installing BCM, always reconnect connectors C1 and C2, then connector C3 last.
  1. Install scan tool. If scan tool works, go to next step. If scan tool does not work, go to SCAN TOOL INOPERATIVE  .
  2. Turn ignition on. Attempt to communicate with all control modules on class 2 serial data circuit. If any module communicates with scan tool, go to next step. If no module communicates with scan tool, go to step  5 .
  3. Check 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, go to appropriate test. See BCM DTC DEFINITIONS  table.
  5. Turn ignition off. 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 circuit between DLC terminal No. 5 (Black/White wire) and ground. If no problem is found, go to next step. If problem is found, repair open or high resistance between DLC and multi-wire ground connector, located on left side of instrument panel. After repair, go to step  16 .
  7. Disconnect Brown 68-pin left instrument panel junction block connector C1. Check for corrosion and damage of terminals. If no problem is found, go to next step. If any looseness or damage exists, repair as necessary. After repair, go to step  16 .
  8. Check for open or short on Purple wire between DLC terminal No. 2 and left instrument panel junction block harness connector C1 terminal D2. If no problem is found, go to next step. If problem is found, repair open or short. After repair, go to step  16 .
  9. Check for continuity between left instrument panel junction block terminals D2, A3 and E3. Check for short to ground on purple wire from left instrument panel junction block harness connector terminals D2, A3 and E3. If no problems are found, go to next step. If a open exists in junction block, replace junction block. If a short to ground exists, repair Purple wire as necessary. After repair, go to step  16 .
  10. Turn ignition off. Disconnect BCM connectors. Check for short to ground or short to power (ignition on) on Purple wire between BCM connector C3 terminal B2 and left instrument panel junction block harness connector C1 terminal E3. See Figure . If no problem is found, go to next step. If problem is found, repair as necessary. After repair, go to step  16 .
  11. Turn ignition off. Disconnect SDM connector. Check for short to ground or short to power (ignition on) on Purple wire between SDM connector terminal A4 and left instrument panel junction block harness connector C1 terminal E3. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, go to step  16 .
  12. Turn ignition off. Disconnect ECBM connector. Check for short to ground or short to power (ignition on) on Purple wire between ECBM connector C1 terminal C8 and left instrument panel junction block harness connector C1 terminal A3. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, go to step  16 .
  13. Turn ignition off. Disconnect PCM connector. Check for short to ground or short to power (ignition on) on Purple wire between PCM connector C1 terminal No. 59 and left instrument panel junction block harness connector C1 terminal A3. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, go to step  16 .
  14. Check terminals of connector and module that is not communicating. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, go to step  16 .
  15. Replace module that is not communicating. See appropriate article for replacement and programming information. Go to next step.
  16. Reconnect all components and connectors. Connect scan tool. Turn ignition on. If scan tool does not communicate, disconnect scan tool , then reconnect to reset communication. Check DTCs for each module. Record each DTC, status (history or current) and which module set the DTC. If any DTCs exist, go to next step. If no DTCs exist, go to step  18 .
  17. Diagnose and repair any DTCs as necessary. See appropriate article for test. See BCM DTC DEFINITIONS  table. After all repairs are complete, go to next step.
  18. Using scan tool, clear all DTCs.
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