B3820 GMC Code - Left Rear Window Down Control Circuit
Quick Answer
The Body Control Module (BCM) grounds the control side of the left rear power window down relay upon receiving a class 2 message from the Driver Door Module (DDM). Common causes include Faulty Left Rear Power Window Switch, Left Rear Power Window Switch harness is open or shorted, Left Rear Power Window Switch circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- B3820 GMC indicates Left Rear Window Down Control Circuit.
- Common causes
- Common causes include Faulty Left Rear Power Window Switch, Left Rear Power Window Switch harness is open or shorted, Left Rear Power Window Switch circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code B3820 GMC Description
What are the Possible Causes of the DTC B3820 GMC?
- Faulty Left Rear Power Window Switch
- Left Rear Power Window Switch harness is open or shorted
- Left Rear Power Window Switch circuit poor electrical connection
- Faulty Body Control Module (BCM)
How to Fix the DTC B3820 GMC?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the B3820 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about B3820 GMC Code
1. What does OBDII code B3820 mean on a GMC?
B3820 indicates an issue in the Left Rear Window Down Control Circuit, suggesting a problem with the electrical system that controls the rear left window's downward movement.
2. What are the common symptoms of code B3820?
Symptoms include the left rear window not lowering, intermittent window operation, or the window moving down without being commanded.
3. What causes code B3820 on a GMC vehicle?
Common causes include a faulty window switch, damaged wiring or connectors in the control circuit, or a malfunctioning window motor.
4. How can I diagnose code B3820 in my GMC?
Inspect the left rear window switch, wiring, and connectors for damage or corrosion. Use a multimeter to test for continuity and ensure proper voltage is reaching the window motor.
5. Can a blown fuse cause code B3820?
Yes, a blown fuse in the circuit can interrupt power to the window control system and trigger this code.
6. How do I fix code B3820 in my GMC?
Repairs may include replacing a faulty window switch, repairing damaged wiring, cleaning corroded connectors, or replacing the window motor if necessary.
7. Is it safe to drive with code B3820 active?
Yes, it is generally safe to drive, but the left rear window may not function properly, which can be inconvenient or a safety concern in certain situations.
8. How much does it cost to fix code B3820?
Repair costs vary depending on the issue. Replacing a window switch or repairing wiring may cost $50–$200, while a window motor replacement can range from $200–$500.
9. Can I clear code B3820 without fixing the problem?
Clearing the code with a scan tool is possible, but the issue will likely return unless the underlying problem is resolved.
10. Could a problem with the Body Control Module (BCM) cause code B3820?
Yes, a malfunctioning BCM can disrupt communication with the left rear window control circuit and trigger this code, though this is less common.
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