Code
B1831
Other
B — Body
Door Unlock Disarm Switch Circuit Open
AI status
Completed
Completed
100%
Causes
- Broken or chafed wiring in the switch circuit
- Disconnected, corroded or pushed-out connector at the switch or BCM
- Faulty door unlock / disarm switch (mechanical/electrical failure)
- Blown fuse or poor power/ground related to the switch supply or BCM
- Poor or intermittent ground connection
- Faulty BCM or input circuit failure in the control module
Symptoms
- Door unlock or disarm function inoperative from interior switch
- Keyless/remote unlock may still work but interior disarm doesn't
- Warning or message related to door lock/disarm on dash (manufacturer-specific)
- DTC B1831 stored and lamp or message may appear intermittently
What to check
- Read and record stored DTCs and freeze frame with a scan tool
- Perform a visual inspection of the door switch, harness, and connectors for damage or corrosion
- Check related fuses and general power/ground for BCM and door modules
- Operate the switch while observing connector for loose pins or intermittent contact
- Scan tool: monitor switch input data while operating the switch
Signal parameters
- With switch unactuated: circuit may be open or at a defined pull-up level—refer to vehicle wiring diagram (typical levels 0–12 V depending on design)
- When switch actuated: continuity expected between signal and ground or a distinct voltage change seen at the BCM input (often near 0 V when pulled to ground or near battery voltage when pulled high)
- Continuity (closed) should show low resistance (
- No signal change at BCM input when operating switch indicates open or wiring fault
Diagnostic algorithm
- Connect a scan tool, confirm B1831 is current/confirmed and record any freeze frame data.
- Verify basic service items: battery voltage, applicable fuses, and BCM power/grounds.
- Visually inspect the door unlock/disarm switch, its mounting, and harness for damage, water intrusion, or corrosion.
- Disconnect the switch connector and check terminal condition; wiggle harness while observing for movement or corrosion.
- With ignition on, backprobe the switch signal pin and observe with a DVOM or lab scope while operating the switch; note voltage change or continuity. Compare to wiring diagram expected behavior.
- If no signal at switch connector, trace continuity between switch connector and BCM connector; repair any open/short/splice issues found.
- If good continuity and correct switch operation at the connector but BCM sees no change, check BCM input pin for damage and consult manufacturer procedure for module testing. Consider replacing BCM only after wiring and switch are confirmed good.
- After repairs, clear DTCs and confirm proper operation and that code does not return.
Likely causes
- Open or intermittent wiring between the switch and BCM
- Corroded/loose connector at the door switch or harness splice
- Failed door unlock/disarm switch
Fault status
Status
Open circuit detected on Door Unlock/Disarm Switch input — no valid switch signal reaching the control module.
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
Similar codes
Repair manuals
Brands with available manuals
7,449
The library contains 7,449 repair and diagnostic manuals. Choose a brand to open the full manual tree by year, model and trim.
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email