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DTC B1440: Power Mode Master Input Circuit Mismatch: Testing

  1. Perform BCM DIAGNOSTIC SYSTEM CHECK  . Go to next step.
  2. Connect scan tool to DLC. Turn ignition switch to RUN position. In BCM input data list, monitor ignition switch input parameters. If all 3 parameters show ON or ACTIVE, go to  6 . If all 3 parameters do not show ON or ACTIVE, go to next step.
  3. Test for open or short to ground in ignition circuits that displayed OFF or INACTIVE. See WIRING DIAGRAMS  . Repair as necessary. After repair, go to step  12 . If circuits are okay, go to next step.
  4. Check for poor terminal contact at BCM connectors. Repair as necessary. After repair, go to step  12 . If terminal contact is okay, go to next step.
  5. Check for poor terminal contact at ignition switch connector. Repair as necessary. After repair, go to step  12 . If terminal contact is okay, go to step  11 .
  6. Turn ignition switch to LOCK position. Using scan tool, monitor ignition switch input parameters. If all ignition switch input parameters display as OFF or INACTIVE, go to next step. If one or more parameters display as ON or ACTIVE, go to step  8 .
  7. Turn ignition switch to ACC position. Using scan tool, observe ignition switch input parameters. If ignition switch IGN 1 and IGN 0 input parameters display as OFF and ACC power input display is ACTIVE, go to step  10 . If ignition switch IGN 1 and IGN 0 input parameters do not display OFF and ACC power input display does not display as ACTIVE, go to step  11 .
  8. Check for short to power in ignition switch circuits that displayed as ON or ACTIVE. See WIRING DIAGRAMS  . Repair as necessary. After repair, go to step  12 . If all circuits are okay, go to next step.
  9. Ensure ignition switch is in LOCK position. Using a test light connected to ground, backprobe at ignition switch connector circuit(s) that displayed as ON or ACTIVE in step  6 . If test light illuminates, go to next step. If test light does not illuminate, go to step  11 .
  10. Replace ignition switch. See ANALOG INSTRUMENT PANELS - IMPALA & MONTE CARLO for removal and installation. After repair, go to step  12 .
  11. Replace BCM. See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION. Perform new BCM setup. See NEW BCM SETUP  under PROGRAMMING. After programming BCM, go to next step.
  12. Operate system to verify repair corrected fault. If fault still exists, go to step  2 .
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