B1835

Door Unlock Disarm Output Circuit Open

Body Chassis/Safety Door Lock Control 🟢 Low — Fix at next service ✅ Safe to Drive
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What This Actually Means

In plain language — no jargon

The door unlock control circuit has an open wire or failed connection, preventing the unlock command from reaching the door lock actuator. Think of it like a broken phone line—the message is trying to get through but the connection is severed.

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Symptoms You May Notice

3 known symptoms for this code
Door locks do not unlock when commanded via key fob or door lock switch
No click or actuator response from door lock motor
Door unlock feature works intermittently or only on some doors
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The BCM monitors the voltage and current draw on the door unlock actuator output circuit. It detects an open circuit when no current flows despite sending the unlock command, or when circuit voltage does not drop as expected. If the circuit remains open for multiple command cycles, the fault is stored.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Output Circuit Current Draw 150–500 mA when actuator energized < 50 mA or no measurable current
Circuit Voltage Drop 2–5 V across solenoid coil during unlock Battery voltage (12+ V) indicating open circuit
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Wiring harness connectors (door lock circuit)
Inspect and reseat connectors at the door lock actuator and BCM; corrosion or loose pins are common culprits.
2
Door lock actuator wiring
Check for pinched, cut, or corroded wires in the door harness and along the door jamb, especially after recent service or accidents.
3
Door lock actuator motor
Replace the faulty solenoid or motor if wiring tests normal and no current flows when unlock is commanded.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1835 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code B1835

What happens after you fix the fault

Once the fault is repaired, B1835 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.