OBD Guide
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B1685

Lamp Dome Input Circuit Failure

B1685 is an OBD-II diagnostic trouble code meaning: Lamp Dome Input Circuit Failure. Common causes: light circuit fuse blown, open or short circuit in wiring. Estimated repair cost: $6–56.

Severity
✅ Low
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$6–56 (est.)

Symptoms

  • The interior light does not work
  • The lamp does not work correctly (flashes, does not turn off)
  • Error B1685 in diagnostic memory

Causes

  • Light circuit fuse blown
  • Open or short circuit in wiring
  • Malfunction of the lamp control relay
  • Problem with the dome light switch
  • Body control module malfunction

How to Fix

  1. Check the interior lighting fuse
  2. Inspect the wiring for damage
  3. Check the operation of the lamp switch
  4. Test control relay
  5. If necessary, replace the body control module

Related codes

B1686B1687

FAQ

What does the B1685 code mean?

B1685 is an OBD-II diagnostic trouble code that indicates: Lamp Dome Input Circuit Failure

What causes a B1685 error code?

The most common causes of B1685 include: Light circuit fuse blown; Open or short circuit in wiring; Malfunction of the lamp control relay; Problem with the dome light switch.

How do I fix a B1685 diagnostic trouble code?

To fix B1685: Check the interior lighting fuse. Inspect the wiring for damage. Check the operation of the lamp switch. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1685?

Yes, but get it checked soon

How much does it cost to fix B1685?

The estimated repair cost for B1685 is $6–56. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat