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DTC U1001-U1254: Loss Of XXX Communication: Testing

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  1. Check for open or short to ground in power circuit(s), ignition inputs and ignition outputs for non-communicating module. See POWER DISTRIBUTION article in WIRING DIAGRAMS. If circuit(s) are okay, go to next step. If circuit(s) are not okay, repair circuit(s) as necessary. After repair, go to step  9 .
  2. Check for open in ground circuit(s) for non-communicating module. See GROUND DISTRIBUTION article in WIRING DIAGRAMS. If circuit(s) are okay, go to next step. If circuit(s) are not okay, repair circuit(s) as necessary. After repair, go to step  9 .
  3. Disconnect splice S207, located in instrument panel harness, approximately 2 inches from park brake warning switch breakout, toward data link connector (DLC) breakout, and splice S153, located in engine harness approximately 3 inches from C100 breakout toward PCM breakout (except 6.5L), or in engine harness, approximately 10 inches from A/C compressor clutch breakout toward C100 breakout (6.5L). Check for continuity in Purple wire between appropriate module and S207 and between S207 and S153. If circuit(s) are okay, go to next step. If circuit(s) are not okay, repair as necessary. After repair, go to step  7 .
  4. Check for open in class 2 serial data line (Purple wire) between Data Link Connector (DLC) and splice S207 for non-communicating module. If circuit is okay, go to next step. If circuit is not okay, repair circuit as necessary. After repair, go to step  7 .
  5. Check battery positive voltage, ignition voltage, ground and class 2 serial data terminals at non-communicating module connector for intermittent, poor connections or terminal tension. If connector is okay, go to next step. If connector is not okay, repair connector as necessary. After repair, go to step  7 .
  6. Replace non-communicating module. After repair, go to step  9 .
  7. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to RUN position. Select display DTCs function for non-communicating module. If scan tool does not display any DTCs that do not begin with a "U", go to next step. If scan tool displays any DTCs that do not begin with a "U", perform appropriate diagnostic system check. See appropriate article for malfunctioning system.
  8. Using scan tool, clear DTCs. Go to next step.
  9. Select display DTCs function for module that had a loss of communication DTC set. If scan tool does not display any DTCs that do not begin with a "U", go to next step. If scan tool displays any DTCs that do not begin with a "U", perform appropriate diagnostic system check. See appropriate article for malfunctioning system.
  10. Using scan tool, clear DTCs. Continue diagnosing and clearing DTCs until all modules have been diagnosed and all DTCs have been cleared.
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