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Scan Tool Does Not Communicate With Class 2 Device

CAUTION: BCM Brown 24-pin connector C1 contains power and ground sources. When removing BCM, always disconnect connector C1 first before disconnecting connectors C2 and C3. When installing BCM, always reconnect connectors C2 and C3, then connector C1 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  6.
  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, go to step  5.
  4. If only U1000 or U1255 exist, go to DTC U1000 & U1255: CLASS 2 COMMUNICATION MALFUNCTION . If any other "U" codes exist, go to DTC U1001-U1097: LOSS OF XXX COMMUNICATIONS .
  5. Diagnose malfunction using DTC U1001-U1097: LOSS OF XXX COMMUNICATIONS  test. After repair, go to BODY CONTROL MODULE (BCM) DIAGNOSTIC SYSTEM CHECK .
  6. Turn ignition off. Disconnect scan tool from DLC. Check DLC terminals No. 2 (Purple wire) and No. 5 (Black 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 BODY CONTROL MODULE (BCM) DIAGNOSTIC SYSTEM CHECK .
  7. Check for open circuit between DLC terminal No. 5 (Black wire) and ground. If no problem is found, go to next step. If problem is found, repair open or high resistance between DLC and ground. After repair, go to BODY CONTROL MODULE (BCM) DIAGNOSTIC SYSTEM CHECK .
  8. Disconnect Natural 12-pin splice pack SP261 connector, located below the data link connector (DLC). 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 BODY CONTROL MODULE (BCM) DIAGNOSTIC SYSTEM CHECK .
  9. Check for open or short on Purple wire between DLC terminal No. 2 and splice pack SP261 harness connector C1 terminal "A". If no problem is found, go to next step. If problem is found, repair open or short. After repair, go to BODY CONTROL MODULE (BCM) DIAGNOSTIC SYSTEM CHECK .
  10. Connect a jumper wire between splice pack SP261 connector terminals "A" (Purple wire) and "M" (Light Green wire). Turn ignition on. Attempt to communicate with BCM. If BCM will not communicate, go to next step. If BCM communicates, go to step  12.
  11. Turn ignition off. Disconnect BCM connectors. Check for short to ground or short to power (ignition on) on Light Green wire between BCM connector C1 terminal A12 and splice pack SP261 terminal "M". See Figure. If no problem is found, go to step  24. If problem is found, repair as necessary. After repair, go to step  26.
  12. Leave jumper wire from step  10 connected. Connect another jumper wire between splice pack SP261 connector terminals "A" (Purple wire) and "B" (Dark Green wire). Turn ignition on. Attempt to communicate with PCM. If PCM will not communicate, go to next step. If BCM communicates, go to step  14.
  13. Turn ignition off. Disconnect PCM connectors. Check for short to ground or short to power (ignition on) on Dark Green wire between PCM connector C4 terminal No. 11 and splice pack SP261 terminal "B". If no problem is found, go to step  24. If problem is found, repair as necessary. After repair, go to step  26.
  14. Leave jumper wire from step  10 connected. Remove jumper wire from splice pack SP261 connector terminal "B". Connect jumper wire between splice pack SP261 connector terminals "A" (Purple wire) and "C" (Dark Green/White wire). Turn ignition on. Attempt to communicate with automatic transfer case shift control module (ATC). If ATC will not communicate, go to next step. If transfer case shift control module communicates, go to step  16.
  15. Turn ignition off. Disconnect ATC connector. Check for short to ground or short to power (ignition on) on Dark Green/White wire between transfer case shift control module connector C1 terminal No. 9 and splice pack SP261 terminal "C". See WIRING DIAGRAMS . If no problem is found, go to step  24. If problem is found, repair as necessary. After repair, go to step  26.
  16. Leave jumper wire from step  10 connected. Remove jumper wire from splice pack SP261 connector terminal "C". Connect jumper wire between splice pack SP261 connector terminals "A" (Purple wire) and "E" (Light Blue wire). Turn ignition on. Attempt to communicate with Electronic Brake Control Module (EBCM). If EBCM will not communicate, go to next step. If EBCM communicates, go to step  18.
  17. Turn ignition off. Disconnect EBCM connectors. Check for short to ground or short to power (ignition on) on Light Blue wire between EBCM connector C1 terminal B6 and splice pack SP261 terminal "E". If no problem is found, go to step  24. If problem is found, repair as necessary. After repair, go to step  26.
  18. Leave jumper wire from step  10 connected. Remove jumper wire from splice pack SP261 connector terminal "E". Connect jumper wire between splice pack SP261 connector terminals "A" (Purple wire) and "F" (Dark Blue wire). Turn ignition on. Attempt to communicate with SIR. If SIR will not communicate, go to next step. If SDM communicates, go to step  20.
  19. Turn ignition off. Disconnect SIR connector. Check for short to ground or short to power (ignition on) on Dark Blue wire between SIR connector terminal No. 4 and splice pack SP261 terminal "F". If no problem is found, go to step  24. If problem is found, repair as necessary. After repair, go to step  26.
  20. Leave jumper wire from step  10 connected. Remove jumper wire from splice pack SP261 connector terminal "F". Connect jumper wire between splice pack SP261 connector terminals "A" (Purple wire) and "G" (Gray wire). Turn ignition on. Attempt to communicate with instrument cluster. If instrument cluster will not communicate, go to next step. If instrument cluster communicates, go to step  22.
  21. Turn ignition off. Disconnect instrument cluster connector. Check for short to ground or short to power (ignition on) on Gray wire between instrument cluster connector terminal B5 and splice pack SP261 terminal "G". If no problem is found, go to step  24. If problem is found, repair as necessary. After repair, go to step  26.
  22. Leave jumper wire from step  10 connected. Remove jumper wire from splice pack SP261 connector terminal "G". Connect jumper wire between splice pack SP261 connector terminals "A" (Purple wire) and "K" (Yellow wire). Turn ignition on. Attempt to communicate with Driver Information Center (DIC). If DIC will not communicate, go to next step. If DIC communicates, go to step  26.
  23. Turn ignition off. Disconnect DIC connector. Check for short to ground or short to power (ignition on) on Yellow wire between DIC connector C1 terminal No. 15 and splice pack SP261 terminal "K". If no problem is found, go to next step. If problem is found, repair as necessary. After repair, go to step  26.
  24. 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  26.
  25. Replace module that is not communicating. See appropriate article for replacement and programming information. After repair, go to next step.
  26. 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  28.
  27. Diagnose and repair all DTCs except history "U" codes set during testing as necessary. See appropriate article for test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  table. After all repairs are complete, go to next step.
  28. Using scan tool, clear all DTCs.
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