B1734
Mirror Driver Vertical 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 vertical adjustment circuit for the driver's side mirror has an open connection, preventing the mirror from moving up and down. It's like a broken wire in the control system that tells the mirror motor when to move.

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Symptoms You May Notice
3 known symptoms for this code
Driver's mirror won't move vertically (up/down)
Mirror control switch unresponsive for vertical adjustment
Warning light or fault indicator illuminated on dashboard
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors voltage and continuity in the vertical mirror adjustment circuit when the switch is activated. It expects to detect a closed circuit with proper voltage levels when the driver commands vertical mirror movement. An open circuit means no current flows, and the ECU detects the fault.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Circuit Voltage 12V when switch activated 0V or no continuity detected
Resistance <5 ohms closed circuit Infinite resistance (open)
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wire harness connector
Locate and reseat the mirror control connector at the door panel to eliminate corrosion or loose pins.
2
Wiring harness
Inspect the vertical adjustment wire for breaks or damage between the door and mirror assembly and repair with solder/crimps.
3
Mirror motor assembly
Replace the entire mirror unit if the internal motor windings are open or burned.