B1684
Mirror Driver/Passenger Switch Circuit Open
Body Chassis/Safety Mirror Control Circuit 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The circuit that controls the driver or passenger side mirror adjustment switch has an open break in the wiring or connector. It's like a light switch with a broken wire—power can't reach the switch to make the mirrors move.

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Symptoms You May Notice
3 known symptoms for this code
Mirror controls don't respond or are inoperative
Mirror adjustment buttons unresponsive on dashboard
No audible relay click when mirror switch is pressed
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the voltage signal from the mirror control switch circuit. When the driver presses the mirror adjustment button, the ECU expects to see a voltage drop or signal state change. An open circuit prevents this signal from reaching the ECU, causing it to log a fault.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Switch Signal Voltage 5V or digital signal present No voltage/signal or open circuit detected
Circuit Continuity Resistance under 10 ohms Infinite resistance (open circuit)
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Mirror switch connector
Inspect the connector at the mirror switch for corrosion, loose pins, or debris and clean or reseat it firmly.
2
Mirror switch wiring harness
Trace the wiring from the switch to the door module for visible breaks, pinches, or damaged insulation and repair or replace as needed.
3
Mirror switch assembly
If continuity tests fail and wiring is intact, replace the mirror switch unit itself.