OBD Guide
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B1778

Mirror Driver Down Circuit Failure

B1778 is an OBD-II diagnostic trouble code meaning: Mirror Driver Down Circuit Failure. Common causes: open or shorted wiring harness, mirror motor malfunction. Estimated repair cost: $56–167.

Severity
✅ Low
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • The mirror does not lower when the button is pressed
  • Intermittent mirror operation
  • The mirror does not respond to commands

Causes

  • Open or shorted wiring harness
  • Mirror motor malfunction
  • Damage to the mirror adjustment switch
  • Problems with the control unit

How to Fix

  1. Check the integrity of the wiring harness
  2. Diagnose the operation of the mirror motor
  3. Check the mirror adjustment switch
  4. Replace damaged components

Related codes

B1777B1779

FAQ

What does the B1778 code mean?

B1778 is an OBD-II diagnostic trouble code that indicates: Mirror Driver Down Circuit Failure

What causes a B1778 error code?

The most common causes of B1778 include: Open or shorted wiring harness; Mirror motor malfunction; Damage to the mirror adjustment switch; Problems with the control unit.

How do I fix a B1778 diagnostic trouble code?

To fix B1778: Check the integrity of the wiring harness. Diagnose the operation of the mirror motor. Check the mirror adjustment switch. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1778?

Yes, but get it checked soon

How much does it cost to fix B1778?

The estimated repair cost for B1778 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat