B1685
Low Severity (Level 2)Lamp Dome Input Circuit Failure
B1685 usually means lamp Dome Input Circuit Failure.
Can you still drive with B1685?
⚠️Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
Typical repair cost: $50 – $600
Severity Level 2 — 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
- Warning light or message on dashboard related to the body electrical system
- Body electronics not functioning as expected
- Diagnostic trouble code (DTC) stored in module memory
- Fault may be intermittent — code may clear itself and reappear
- Reduced vehicle functionality related to the body electrical system
Possible Causes
- Failed body control module (BCM) or sensor — internal fault from age, heat cycling, and vibration
- Damaged wiring or corroded connector in the body electrical system circuit
- Blown fuse for the body electrical system circuit — check before replacing components
- Faulty control module/PCM
- Loose or corroded ground point shared by the body electrical 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 ($1-95 at shop, free at auto parts store for basic scan)
- Visually inspect the body electrical system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $76 diagnostic fee at shop)
- Replace body control module (BCM) or sensor if testing confirms it has failed — use OEM quality, avoid the cheapest no-name aftermarket parts that fail in a year ($50-600)
- Check and replace any blown fuses in the body electrical system fuse circuit — if fuse blows again, there's still a short that needs to be found ($2-18 for fuses)
- Perform a wiggle test on the body electrical system wiring harness while monitoring live data — see if the fault returns when you move the harness at different points ($0-137 diagnostic labor)
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 B1685 mean?
B1685 stands for "Lamp Dome Input Circuit Failure". B1685 usually means lamp Dome Input Circuit Failure.
Can you drive with B1685?
Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
How much does it cost to fix B1685?
Repair costs for B1685 typically range from $50 to $600, 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 ($1-95 at shop, free at auto parts store for basic scan); Visually inspect the body electrical system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $76 diagnostic fee at shop); Replace body control module (BCM) or sensor if testing confirms it has failed — use OEM quality, avoid the cheapest no-name aftermarket parts that fail in a year ($50-600).
Will B1685 clear itself?
Explore Repair Costs
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