Body Control Module - Left Rear Door Control Circuit
Fault in the left rear door control circuit of the Body Control Module.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The Body Control Module (BCM) is sensing an issue with the circuit that controls the left rear door. This could be due to a faulty switch, bad wiring, or a damaged module.
What the computer is actually seeing
The BCM monitors the voltage levels across the left rear door control circuit. If it detects a voltage that is lower than 0.2 volts or higher than 10 volts when the circuit should be active, it sets the B1581 code.
What a healthy reading looks like
Active circuit should show around 12 volts when the door is in use, and close to 0 volts when the door is not being activated.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connectors at the left rear door for damage or corrosion. If damaged, repair or replace as needed.
- 22. Test the door control switch for continuity. It should show continuity when pressed. Replace if faulty.
- 33. Measure the voltage at the left rear door control circuit while operating the switch. It should be around 12 volts. If not, track for wiring issues or BCM faults.
- 44. If wiring and switch are good, consider testing or replacing the Body Control Module (BCM).
Common causes
- Faulty door control switch
- Damaged wiring or connector in the left rear door circuit
- Faulty Body Control Module (BCM)
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, it’s drivable but the left rear door functions may be impaired.
Will the issue return after repair?
If the repair is done correctly and the cause is fixed, the code should not return.
Why does this code pair with other codes?
It may indicate similar issues in the door control circuits which could involve shared wiring or components.
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