B1778
Low Severity (Level 1)Mirror Driver Down Circuit Failure
B1778 usually means mirror Driver Down Circuit Failure.
Can you still drive with B1778?
✅Safe to drive — this is an informational or minor issue. Schedule diagnosis at your convenience.
Typical repair cost: $50 – $400
Severity Level 1 — Low
This code indicates a minor issue that is unlikely to cause immediate driveability problems. You can typically continue driving but should have the vehicle inspected at your earliest convenience.
Common Symptoms
- Power mirrors not functioning as expected
- Power mirrors won't adjust — stuck in current position
- Warning light or message on dashboard related to the power mirror system
- Diagnostic trouble code (DTC) stored in module memory
Possible Causes
- Failed mirror motor — internal fault from age, heat cycling, and vibration
- Damaged wiring or corroded connector in the power mirror system circuit
- Blown fuse for the power mirror system circuit — check before replacing components
- Faulty control module driving the mirror motor
- Loose or corroded ground point shared by the power mirror system
Common Fixes
- Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($48-122 at shop, free at auto parts store for basic scan)
- Visually inspect the power mirror system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $128 diagnostic fee at shop)
- Inspect the wiring boot where it passes from the body into the door — this is the #1 failure point. Peel back the rubber boot and check for broken/cracked wires ($0 DIY inspection)
- Replace mirror motor if testing confirms it has failed — use OEM quality, avoid the cheapest no-name aftermarket parts that fail in a year ($50-400)
- Check and replace any blown fuses in the power mirror system fuse circuit — if fuse blows again, there's still a short that needs to be found ($1-10 for fuses)
Estimated Repair Cost
These are estimated costs based on generic repair data. Actual costs may vary depending on your vehicle, location, and labor rates.
Frequently Asked Questions
What does B1778 mean?
B1778 stands for "Mirror Driver Down Circuit Failure". B1778 usually means mirror Driver Down Circuit Failure.
Can you drive with B1778?
Safe to drive — this is an informational or minor issue. Schedule diagnosis at your convenience.
How much does it cost to fix B1778?
Repair costs for B1778 typically range from $50 to $400, depending on your vehicle make, model, and local labor rates. Common fixes include: Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($48-122 at shop, free at auto parts store for basic scan); Visually inspect the power mirror system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $128 diagnostic fee at shop); Inspect the wiring boot where it passes from the body into the door — this is the #1 failure point. Peel back the rubber boot and check for broken/cracked wires ($0 DIY inspection).
Will B1778 clear itself?
Explore Repair Costs
Related OBD-II Codes
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