DTC B1127: Driver's Door Key Cylinder Switch Input Circuit Malfunction (Simultaneous input of lock and unlock signal)

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC ChecksBody Electrical Troubleshooting - B-CAN System Diagnosis Test Mode 1 and Test Mode 2 (without the HDS)Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode B - Control Unit Not CommunicatingBody Electrical Troubleshooting - B-CAN System Diagnosis Test Mode C - No DTCs and Output Won't Shut OFFBody Electrical Troubleshooting - B-CAN System Diagnosis Test Mode D - No DTCs and Output Won't Turn ON .

NOTE:  Refer to the Electrical Wiring Diagrams for the location of the under-dash fuse/relay box connectors.

• 1. Problem verification (driver's door key cylinder switch in the neutral position):

  1. Check the parameter(s) below with the HDS.

  Signal	Current conditions
  	Values	Unit
  Driver's Door Key Cylinder Switch(LOCK)
  Driver's Door Key Cylinder Switch(UNLOCK)

  Is either information indicator ON?

  YES 

  Go to step 4.

  NO 

  Go to step 2.

• 2. Problem verification (driver's door key cylinder switch in the lock position):

  1. With the driver's door key cylinder in the lock position, check the parameter(s) below with the HDS.

  Signal	Current conditions
  	Values	Unit
  Driver's Door Key Cylinder Switch(LOCK)
  Driver's Door Key Cylinder Switch(UNLOCK)

  Are both information indicators ON?

  YES 

  Go to step 3.

  NO 

  Intermittent failure, the system is OK at this time.

• 3. Shorted wire check (DR KEY CYL UNLOCK to DR KEY CYL LOCK line):

  1. Turn the vehicle to the OFF (LOCK) mode.

  2. Disconnect the following connector.

  Driver's door latch 10P connector

  3. Connect terminals A and B with a jumper wire.

  Terminal A	Under-dash fuse/relay box connector X (10P) No. 10
  Terminal B	Body ground

  4. Check the parameter(s) below with the HDS.

  Signal	Current conditions
  	Values	Unit
  Driver's Door Key Cylinder Switch(LOCK)
  Driver's Door Key Cylinder Switch(UNLOCK)

  Are both information indicators ON?

  YES 

  Repair a short between the wires.

  NO 

  The DR KEY CYL UNLOCK to DR KEY CYL LOCK wire is OK. Faulty driver's door key cylinder switch; replace the driver's door latch .

• 4. Determine possible failure area (driver's door latch, others):

  1. Turn the vehicle to the OFF (LOCK) mode.

  2. Disconnect the following connector.

  Driver's door latch 10P connector

  3. Check the parameter(s) below with the HDS.

  Signal	Current conditions
  	Values	Unit
  Driver's Door Key Cylinder Switch(LOCK)
  Driver's Door Key Cylinder Switch(UNLOCK)

  Is either information indicator ON?

  YES 

  Go to step 5.

  NO 

  Faulty driver's door key cylinder switch; replace the driver's door latch .

• 5. Shorted wire check (DR KEY CYL UNLOCK, DR KEY CYL LOCK lines):

  1. Turn the vehicle to the OFF (LOCK) mode.

  2. Disconnect the following connector.

  Under-dash fuse/relay box connector X (10P)

  3. Check for continuity between test points 1 and 2 individually.

  Test condition	Vehicle OFF (LOCK) mode Driver's door latch 10P connector: disconnected Under-dash fuse/relay box connector X (10P): disconnected
  Test point 1	Under-dash fuse/relay box connector X (10P) No. 9
  Test point 2	Body ground

  Test point 1	Under-dash fuse/relay box connector X (10P) No. 10
  Test point 2	Body ground

  Are there continuity?

  YES 

  Repair a short to ground in the wire.

  NO 

  The DR KEY CYL UNLOCK and DR KEY CYL LOCK wires are OK. Faulty MICU; replace the under-dash fuse/relay box .