DTC Troubleshooting: B1127DTC B1127: Driver's Door Key Cylinder Switch Signal Error
NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A.
Troubleshooting - B-CAN System Diagnosis Test Mode A 1.
Clear the DTCs with the HDS.
2.
Turn the ignition switch to LOCK (0), and then back to ON (II).
3.
Insert the ignition key into the driver's door key cylinder switch, and turn the key to the LOCK and UNLOCK positions ten times.
4.
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.
5.
With the driver's door key cylinder in the neutral position, select KEYLESS with the HDS, and enter DATA LIST.
6.
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 - Go to step 12.
NO - Go to step 7.
7.
Disconnect the driver's door lock actuator 10P connector.
8.
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.
9.
Turn the ignition switch to LOCK (0).
10.
Disconnect under-dash fuse/relay box connector T (34P).
11.
Check for continuity between under-dash fuse/relay box connector T (34P) terminals No. 31 and No. 32 and body ground.
Is there continuity?
YES - Repair a short to ground in the wire.
NO - Faulty MICU; replace the under-dash fuse/relay box.
12.
Turn the ignition switch to LOCK (0).
13.
Disconnect the driver's door lock actuator 10P connector.
14.
Disconnect under-dash fuse/relay box connector T (34P).
15.
Check for continuity between under-dash fuse/relay box connector T (34P) terminals No. 31 and No. 32.
Is there continuity?
YES - Repair a short to ground in the wire.
NO - Substitute a known-good MICU, and recheck. If the symptom/indication goes away, replace the original MICU, if not, replace the driver's door lock actuator.
