2001 Toyota 4Runner B1300, B1575, C1446 Fault Codes - Door Locks Fail After Slamming Passside Door
I own a 2001 Toyota 4Runner and am experiencing a recurring issue: when I slam the passenger-side door, all door locks engage automatically but will not open using keyless entry. If I attempt to manually operate the locks with a physical key, they fail to function properly—either not moving at all or working only briefly before slowing down and eventually stopping. After waiting several minutes, the manual lock operation works about four times before gradually deteriorating until it stops entirely. The Body Control Module (BCM) is displaying three diagnostic trouble codes: B1300, B1570, and C1446. I suspect this issue may be related to a communication failure between the door lock system and the BCM, especially after physical impact or forceful door closure. Thanks for any insight—Bill
Slamming the passenger-side door may trigger an electrical signal or vacuum disturbance that causes the system to interpret a manual lock command. Since the body control module never receives a valid remote signal to lock, it assumes all doors are unlocked and incorrectly responds by locking them instead. This miscommunication leads to failure in keyless entry and erratic manual lock operation. The B1300 (Door Lock Control Module) and B1575 (Body Control Module Communication) codes support this theory, while C1446 may indicate a fault in the door lock actuator or wiring harness.