B1127

Control System DTCs

DTC Troubleshooting: B1127

DTC B1127 : Driver's Door Key Cylinder Switch Input Circuit Malfunction (Simultaneous Input of Lock and Unlock Signal)

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





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.





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 ignition switch to LOCK (0).

-2. Disconnect the following connector.





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









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





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 Service and Repair.

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

-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connector.





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





Is either information indicator ON?
-YES- Go to step 5.
-NO- Faulty driver's door key cylinder switch; replace the driver's door latch Service and Repair.

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

-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connector.





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














Is 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 Under-Dash Fuse/Relay Box Removal and Installation.