B1D23

Code

Generic B — Body

Left rear door lock motor circuit malfunction

Brand: Generic

Type: B — Body

Views: UK: 9 EN: 17 RU: 10

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Page language: EN

Causes

Open or shorted wiring to left rear door lock actuator
Corroded or disconnected connector at actuator or door harness
Failed door lock motor/actuator (mechanical jam or electrical failure)
Bad ground at door or body control module (BCM)
Blown fuse or faulty relay in the lock power circuit
Body control module or door module output transistor fault

Symptoms

Left rear door does not lock or unlock with key fob, interior switch, or auto-lock
Grinding or no noise from left rear door when lock command given
Intermittent operation of left rear lock
Other doors operate normally while left rear fails
Possible blown fuse or multiple door functions affected if fuse/relay is shared

What to check

Read and record freeze-frame/live-data and stored DTCs from BCM/door module
Visually inspect left rear door harness, connector, and actuator for damage/corrosion
Check fuses and relays related to door locks
Backprobe actuator connector and check for command voltage/pulse while operating lock
Measure continuity between actuator connector and BCM connector for opens/shorts
Check ground integrity at door and chassis ground points

Signal parameters

Command voltage: typically 0–12 V depending on vehicle (12 V applied for lock/unlock or H-bridge drive switching to ground)
Actuator coil resistance: typically a few ohms up to low tens of ohms (vehicle-specific)
Normal actuator current draw: commonly 0.5–5 A during movement; stall current will be higher (consult vehicle spec)
Open-circuit: infinite resistance between connector terminals when actuator disconnected
Short to battery: near 0 Ω between power feed and battery +
Short to ground: near 0 Ω between power feed and chassis ground when inactive

Diagnostic algorithm

Verify DTC: Connect scan tool, record B1D23 and any related codes, note conditions when fault set (ignition state, lock/unlock attempts).
Visual inspection: Check door edge, connector boot, and harness for corrosion, pins pushed out, water entry, or chafing at hinge.
Fuse/relay: Check and replace any blown fuses or suspect relays in the door lock circuit. Re-test operation.
Backprobe while operating: With connector connected, backprobe actuator power and ground leads and operate lock/unlock. Observe voltage or switching pattern.
Apply known-good power: Disconnect actuator and apply 12 V directly to actuator to confirm motor runs and moves lock mechanism. If actuator works, suspect wiring/module.
Resistance and current: Measure resistance of actuator and measure current draw during operation (use clamp meter or inline ammeter). Compare to spec — high resistance or excessive current indicates internal fault or mechanical binding.
Continuity and shorts: With ignition off and battery disconnected if required, check continuity from BCM/door module pin to actuator connector, and check for shorts to ground or battery.
Wiggle test: With connector back in place, wiggle harness through door travel while commanding lock — look for intermittent changes and inspect for broken conductors.
Module outputs: If wiring and actuator are good, verify BCM/door module output with scope or multimeter for correct switching/pulse. Consider module replacement only after wiring and actuator verified.
Repair and verify: Repair or replace damaged wiring, connector, actuator, fuse, or module as indicated. Clear codes and cycle lock commands to confirm repair and ensure code does not return.