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DTC Troubleshooting: B1127

DTC B1127:
 Driver's Door Key Cylinder Switch Input Circuit Malfunction (Simultaneous input of lock and unlock signal)
  1. Clear the DTCs with the HDS.
  1. Turn the ignition switch to LOCK (0), and then back to ON (II).
  1. Insert the ignition key into the driver's door key cylinder switch, and turn the key to the LOCK and UNLOCK positions 10 times.
  1. Check for DTCs with the HDS.
Is DTC B1127 indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure, the driver's door key cylinder switch system is OK at this time. Check for loose or poor connections.■
  1. With the driver's door key cylinder in the neutral position, select KEYLESS with the HDS, and enter the DATA LIST.
  1. Check the ON/OFF information of the DRIVER'S DOOR KEY CYLINDER SWITCH (LOCK) and DRIVER'S DOOR KEY CYLINDER SWITCH (UNLOCK) in the DATA LIST.
Are both information indicators OFF?
YES -
Check the wires for continuity between the under-dash fuse/relay box and driver's door key cylinder switch. If there is continuity, the MICU is faulty. Replace the under-dash fuse/relay box.
NO -
Go to Step 7 .
  1. Disconnect the driver's door lock actuator 10P connector.
  1. Check the ON/OFF information of the DRIVER'S DOOR KEY CYLINDER SWITCH (LOCK) and DRIVER'S DOOR KEY CYLINDER SWITCH (UNLOCK) in the DATA LIST.
Are both information indicators OFF?
YES -
Faulty driver's door key cylinder switch; replace the driver's door lock actuator.■
NO -
Go to Step 9 .
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect under-dash fuse/relay box connector E (12P).
  1. Check for continuity between the No. 4 (UNLOCK) and No. 3 (LOCK) terminals of under-dash fuse/relay box connector E (12P) and body ground individually.
Is there continuity?
YES -
Repair a short to ground in the LOCK or UNLOCK wire.■
NO -
Go to Step 12 .

  1. Check for continuity between the No. 4 (UNLOCK) and No. 3 (LOCK) terminals of under-dash fuse/relay box connector E (12P).
Is there continuity?
YES -
Repair a short in the wire between the LOCK and UNLOCK wires.■
NO -