B1631 — Mirror Driver Left Circuit Failure #

Note: The wording of this DTC may vary depending on the vehicle manufacturer.

• Mirror Driver Left Circuit Malfunction (Ford)
• Left Power Mirror Driver Circuit Failure (Chrysler)
• Driver Side Mirror Motor Circuit Error (GM/Chevrolet)

Summary of DTC B1631 #

The Diagnostic Trouble Code B1631 indicates a detected issue in the driver side mirror motor circuit. In simple terms, the vehicle’s electronic control unit (ECU) has spotted an electrical problem—such as an open or short circuit—affecting the system responsible for moving or adjusting the left (driver’s side) mirror. This code is most often set by the Body Control Module (BCM), which monitors the status and function of body-related electronics. While this fault rarely affects vehicle safety, it can hinder your ability to adjust the left mirror for optimal visibility. Prompt attention is recommended, especially if you use the mirror adjustment frequently or share your vehicle with other drivers.

Common Symptoms for DTC B1631 #

Usually, B1631 will manifest through one or more driver-visible signs. Most often, these symptoms relate to the mirror’s inability to respond to adjustment commands. Sometimes, there may be additional electrical glitches in the mirror system. Here’s what you might notice:

• Driver side (left) mirror does not move when adjustment switch is operated
• Mirror only moves in certain directions or not at all
• Mirror adjustment is slow or intermittent
• Unusual noises from the mirror assembly (clicking, buzzing)
• Mirror memory settings fail to recall or store positions
• Possible error message or warning light on the dashboard (in some vehicles)

Likely Causes of B1631 (Most to Least Common) #

The root causes of B1631 tend to revolve around wiring and electrical problems. Here are the likely culprits, ordered from most to least frequent:

1. Damaged or corroded wiring between the mirror and door control modules
2. Faulty mirror motor in the driver side mirror assembly
3. Defective mirror adjustment switch or controls inside the door
4. Poor ground connection at the mirror or door module
5. Blown fuse in the mirror/mirror adjustment circuit
6. Body Control Module (BCM) malfunction (rare)
7. Aftermarket mirror or wiring modifications causing incompatibility

Step-by-Step Diagnosis for B1631 #

To isolate and fix the B1631 code, follow these logical diagnostic steps. Always use proper safety gear and disconnect the battery if working with wiring:

• Verify the code and clear it; see if it returns after operating the mirror controls.
• Check mirror adjustment function to confirm symptoms (all directions, memory presets if equipped).
• Inspect mirror fuse and related fuses in the vehicle’s fuse box.
• Visually examine wiring harnesses at the mirror, inside the door, and at the switch for damage, corrosion, or pinched wires.
• Test power and ground at the mirror connector using a digital multimeter.
• Test the mirror adjustment switch for proper output (refer to OEM wiring diagrams).
• If accessible, bench-test the mirror motor by applying direct power and ground.
• Scan for related codes (especially in the BCM or door module) that might indicate broader electrical issues.
• If all components test good, suspect a module fault and consult OEM technical resources.

Possible Repairs for B1631 #

Depending on your findings, fixing B1631 typically involves addressing the most common electrical issues. Here are the most effective repairs:

• Repair or replace damaged wiring or corroded connectors
• Replace the driver side mirror assembly (if mirror motor is faulty)
• Replace the mirror adjustment switch (if defective)
• Clean and secure ground connections for the mirror circuit
• Replace blown fuses and identify/fix the root cause of the overload
• Update or reprogram the BCM if an internal error is detected (rare)
• Correct any improper aftermarket installations (mirrors, wiring, etc.)

Is It Safe to Drive with B1631? #

Yes, you can safely drive your vehicle with code B1631 present. This fault does not affect engine performance, braking, or critical safety systems. However, if you are unable to adjust the driver’s side mirror, your field of view may be compromised, especially if you share the vehicle or need to change settings frequently. For optimal visibility and comfort, address the issue at your earliest convenience.

Vehicles Most Commonly Affected by B1631 #

While B1631 is a generic OBD-II code, it appears most frequently on vehicles with power-adjustable mirrors and advanced mirror memory features. The following makes and models are often reported:

• Ford (F-150, Explorer, Escape, Fusion)
• Chrysler (300, Pacifica, Town & Country)
• Chevrolet/GMC (Silverado, Tahoe, Acadia)
• Dodge (Ram, Charger, Durango)
• Jeep (Grand Cherokee, Wrangler)
• Lexus and Toyota (with memory mirrors)

Common Mistakes & Best Practices for B1631 Diagnosis #

Even seasoned technicians can make errors when diagnosing B1631. To avoid wasted time and repeat repairs, keep these points in mind:

• Don’t replace the mirror assembly before checking the wiring and switch—external damage is rare.
• Avoid skipping a thorough inspection of connectors in the door and at the mirror base (water intrusion is common).
• Always use OEM wiring diagrams to verify pinouts before testing or applying power directly.
• Don’t overlook related codes in the BCM, as they may point to a broader issue.
• When replacing parts, use OEM components to ensure compatibility and reliability.

Quick FAQ for B1631 #

Here are some rapid answers to common owner and technician questions about B1631:

• Q: Will this code affect my power folding or heated mirror functions?
  A: Not directly. B1631 specifically targets the adjustment motor circuit, but other codes may appear for folding or heating issues.
• Q: Can a dead battery or jump start cause B1631?
  A: It’s unlikely. Power fluctuations rarely trigger this code, unless a wiring issue or blown fuse is also present.
• Q: Can I replace the mirror myself?
  A: If you have basic tools and follow safety procedures, replacing the mirror assembly is generally straightforward. Always disconnect the battery and consult a service manual for your vehicle.