B1684 — Mirror Driver/Passenger Switch Circuit Open #

Note: The definition of this code can differ depending on the vehicle manufacturer (OEM). Always refer to your vehicle’s specific service manual for the exact terminology and troubleshooting steps.

• Mirror Driver/Passenger Switch Circuit Open (General/Chrysler/Ford/GM)
• Mirror Control Switch Circuit Open (Nissan/Infiniti)
• Mirror Adjustment Switch Open Circuit (Toyota/Lexus)

Summary of DTC B1684 #

The B1684 diagnostic trouble code (DTC) signals that the circuit controlling the driver or passenger side power mirror switch is not properly closed, meaning an open circuit has been detected. In simpler terms, the vehicle’s onboard computer (often called the Body Control Module or BCM) has noticed a break or disconnection in the wiring or switch that lets you adjust your mirrors. This code is most often triggered when you try to use the mirror controls and nothing happens, but it might also set even if you don’t attempt to adjust the mirrors. While this fault typically doesn’t affect vehicle safety, it does impact convenience and can point to underlying electrical issues. Addressing this code promptly can help avoid further electrical problems.

Common Symptoms for Code B1684 #

If your car has stored the B1684 code, you’ll likely notice some unmistakable signs. While the issue might seem minor at first glance, the following symptoms can help you confirm a problem is present:

• Power mirrors (driver and/or passenger side) do not respond to control inputs
• No movement or adjustment when using the mirror switch
• Unusual clicking or no sound at all from the mirror motor area
• “Mirror switch not working” message (on some digital dashboards)
• Occasionally, the power mirror fuse may blow repeatedly

Probable Causes for Code B1684 #

This DTC is most often caused by simple electrical issues, but don’t underestimate the value of methodically checking each possibility. Here are the most frequent root causes, ranked by how commonly they occur:

1. Damaged or disconnected mirror switch wiring harness
2. Faulty mirror control switch
3. Open or corroded connector at the mirror or switch
4. Blown fuse in the mirror control circuit
5. Faulty power mirror motor (rare, but possible)
6. Body Control Module (BCM) malfunction (least common)

Step-by-Step Diagnostic Procedure for Code B1684 #

Diagnosing the B1684 code doesn’t have to be daunting. With a systematic approach, even DIYers can pinpoint the culprit. Here’s a step-by-step process to follow:

• 1. Visual inspection: Check the mirror switch, connectors, and wiring for visible signs of damage, corrosion, or disconnection. Wiggle the wiring while monitoring if the mirrors respond.
• 2. Fuse check: Locate and inspect the fuse(s) linked to the power mirror circuit. Replace any blown fuses, but investigate why it blew before simply swapping it out.
• 3. Switch function test: Using a digital multimeter, confirm that voltage is present at the mirror switch when the ignition is ON. Test switch outputs as you press each direction.
• 4. Continuity testing: With the battery disconnected, check for continuity across the mirror switch circuit from the switch connector to the mirror and to the BCM if applicable.
• 5. Connector integrity: Unplug and inspect all connectors for bent pins, oxidation, or loose fit. Clean and reconnect as needed.
• 6. Mirror motor test: If wiring and switch test good, check the mirror motor for resistance or signs of internal failure.
• 7. BCM scan: As a last step, use a scan tool to verify if the BCM is receiving the switch signal and is not storing additional related codes.

Possible Repairs for Code B1684 #

Once the root cause is identified, you can proceed with the appropriate repair—don’t just clear the code and hope for the best. Here are the most common fixes mapped to their causes:

• Repair or replace damaged wiring between the switch, mirror, and BCM.
• Replace the mirror control switch if found faulty during testing.
• Clean or replace corroded connectors at the switch or mirror side.
• Replace any blown fuses and address the underlying short-circuit or overload.
• Replace the power mirror motor if it fails resistance or function tests.
• In rare cases, reprogram or replace the BCM if a module fault is confirmed.

Is It Safe to Drive With Code B1684? #

Yes, you can usually drive with code B1684 present, as it does not affect core vehicle safety or performance systems. However, being unable to adjust your mirrors can be a safety concern if your mirrors are misaligned—especially when changing lanes or reversing. If your mirrors are stuck in a position that limits rearward visibility, address the issue before regular driving resumes. If the mirrors are set safely, you can continue driving while planning a timely repair.

Vehicles Most Commonly Affected by Code B1684 #

This code is seen across a range of vehicle makes, particularly where power mirrors are standard equipment. Based on reported cases and OEM service literature, these makes and models are most often affected:

• Chrysler, Dodge, and Jeep models (various years)
• Ford F-Series, Explorer, and Taurus
• Chevrolet Silverado, Malibu, and Impala
• Toyota Camry, Corolla, Highlander
• Nissan Altima, Maxima, Rogue
• Honda Accord and Civic (select years)

Common Mistakes & Best Practices for Code B1684 #

When chasing down electrical gremlins, it’s easy to get sidetracked. Avoid these pitfalls and follow these pro tips for a smoother repair process:

• Overlooking blown fuses without checking for underlying shorts — always ask why a fuse blew before replacing it.
• Replacing the switch or mirror motor prematurely — test the wiring and connectors first.
• Ignoring connector corrosion — even minor oxidation can break the circuit.
• Not performing a wiggle test — gently manipulate wires and connectors to reveal intermittent faults.
• Clearing the code before confirming repairs — always verify proper function before erasing DTCs.

Express FAQ for Code B1684 #

Still puzzled by B1684? Here are quick answers to the most common questions:

• Q: Can a dead battery trigger B1684?
  A: Not directly. However, low or fluctuating voltage can sometimes cause temporary electrical glitches, but a true open circuit will persist after the battery is recharged.
• Q: Do I need special tools to fix this code?
  A: Most repairs can be handled with basic tools: a digital multimeter, small screwdrivers, and contact cleaner. For rare BCM faults, a professional scan tool may be needed.