Faulty passenger door lock switch, worn contacts or internal failure.; Damaged or corroded wiring in the passenger door lock switch circuit, often at the door hinge area.; Loose or corroded electrical connector at the switch or BCM.; Short to ground or short to voltage in the switch wiring.; Failed body control module (BCM) or door control module, though less common.; Water intrusion into the door or switch assembly causing corrosion.

DTC codes / B02xx · Airbags, seats, doors, lights and comfort systems / B0270

B0270Passenger Door Lock Switch Circuit

Q: What does code B0270 mean?

Passenger Door Lock Switch Circuit. B0270 indicates that the body control module (BCM) has detected an abnormal condition in the passenger door lock switch circuit, such as an open, short, or unexpected voltage. The BCM monitors the switch inputs to command the door lock actuators, and when the signal does not match expected values, it stores this code and may disable the passenger door lock function.

B0270 indicates that the body control module (BCM) has detected an abnormal condition in the passenger door lock switch circuit, such as an open, short, or unexpected voltage. The BCM monitors the switch inputs to command the door lock actuators, and when the signal does not match expected values, it stores this code and may disable the passenger door lock function.

SystemBody

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

The passenger door lock switch does not lock or unlock the doors from the passenger side.
The central locking system may work from the driver's door but not from the passenger door switch.
The door lock switch may feel stuck or unresponsive when pressed.
In some vehicles, the passenger door lock may operate intermittently or only in one direction.
Often no symptoms besides the warning light, especially if the switch is only used occasionally.

Common causes, most likely first

Faulty passenger door lock switch, worn contacts or internal failure.
Damaged or corroded wiring in the passenger door lock switch circuit, often at the door hinge area.
Loose or corroded electrical connector at the switch or BCM.
Short to ground or short to voltage in the switch wiring.
Failed body control module (BCM) or door control module, though less common.
Water intrusion into the door or switch assembly causing corrosion.

How to diagnose and fix it

Verify the code with a scan tool and check for any related body codes in the BCM.
Inspect the passenger door lock switch for physical damage, sticking, or contamination.
Disconnect the switch and check for continuity or resistance across the switch terminals in both lock and unlock positions.
Check the wiring harness between the passenger door and the BCM for chafing, corrosion, or loose connectors, especially at the door hinge boot.
Measure voltage and ground at the switch connector with the key on to confirm power and ground are present.
If wiring and switch test good, perform a resistance test on the circuit to the BCM and check for shorts to ground or voltage.
Replace the faulty switch or repair the wiring as needed, then clear the code and verify the passenger door lock operates correctly.

Common misdiagnosis of passenger door lock switch codes

A door lock switch that tests fine on the bench can still set B0270 if the door hinge wiring is intermittently shorting as the door opens and closes.
The BCM may set this code if the switch signal is out of range for a fraction of a second, so a slow-acting multimeter might miss the fault; a graphing scan tool is better.
Water leaks from the window seal or door handle gasket often corrode the switch connector, causing this code without any visible damage to the switch itself.
Some vehicles use a multiplexed signal on the door lock switch circuit, so a standard continuity test can give false results; consult the wiring diagram for the specific vehicle.
Replacing the BCM without first checking the switch and wiring is a costly mistake, as the BCM is rarely the root cause of B0270.

Can I keep driving with B0270?

The vehicle remains safe to drive because the passenger door lock switch is a convenience feature and does not affect engine or brake operation. You can continue driving, but avoid relying on the passenger door switch for locking the vehicle and use the driver's door or key fob instead until repaired.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.