DTC Troubleshooting: B1127

DTC B1127: Driver's Door Key Cylinder Switch Signal Error Clear the DTCs using the HDS. Cycle the ignition switch to OFF, and then back ON. Operate the driver's door key cylinder. Check the DTCs by selecting the DTCs MENU (DTCs) from the HDS. Is DTC B1127 indicated?
YES | - | Go to Step 5 .
NO | - | Intermittent failure. The driver's door key cylinder system is OK at this time.■
With no driver's door key cylinder operation, select the TEST MODE MENU from the HDS, and enter the DATA LIST. Check the ON/OFF information of the DRV KEY CYL LK and DRV KEY CYL UNLK in the DATA LIST. Are both information indicators OFF?
YES | - | Go to Step 7 .
NO | - | Go to Step 10 .
Turn the driver's door key cylinder to the LOCK and UNLOCK positions with the ignition key and check the ON/OFF information of the DRV KEY CYL LK and DRV KEY CYL UNLK in the DATA LIST. Is the DRV KEY CYL LK (DRV KEY CYL UNLK) information indicator ON when the key cylinder is in the LOCK (UNLOCK) position, and OFF when the key is returned to the neutral position?
YES | - | Intermittent failure, the door multiplex control unit (power window master switch) is OK at this time.■
NO | - | Go to Step 8 .
Disconnect the driver's door key cylinder switch 3P connector. Check for continuity between the No. 3 (LOCK) and No. 1 (UNLOCK) terminals of the driver's door key cylinder switch 3P connector and the No. 8 (LOCK) and No. 21 (UNLOCK) terminals of the power window master switch 23P connector. Is there continuity?
YES | - | Faulty driver's door key cylinder switch.■
NO | - | Repair an open in the WHT/RED (LOCK) or WHT (UNLOCK) wire.■
Disconnect the driver's door key cylinder switch 3P connector. Check the ON/OFF information of the DRV KEY CYL LK and DRV KEY CYL UNLK in the DATA LIST. Are both information indicators OFF?
YES | - | Faulty driver's door key cylinder switch.■
NO | - | Go to Step 12 .

Check for continuity between the No. 3 (LOCK) and No. 1 (UNLOCK) terminals of the driver's door key cylinder switch 3P connector and body ground. Is there continuity?
YES | - | Repair a short in the WHT/RED (LOCK) or WHT (UNLOCK) wire.■
NO | - | Faulty door multiplex control unit; replace the power window master switch.■