Passenger Mirror Up Circuit Failure
Diagnostic trouble code B1782 indicates a fault in the passenger side mirror up circuit, specific to Toyota and Lexus vehicles. This code is triggered when the mirror control module detects an open circuit, short circuit, or abnormal resistance in the wiring or motor that controls the vertical adjustment of the passenger exterior mirror. The issue is typically electrical in nature and does not affect vehicle drivability.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty passenger mirror motor with worn brushes
- Damaged, cut, or corroded wiring in the passenger door harness
- Loose, corroded, or bent pins in the mirror connector
- Short to ground or power in the vertical adjustment motor wires
- Faulty mirror control switch (master switch)
- Internal failure of the body ECU or mirror control module
3. Symptoms You Will Notice
- Passenger mirror does not move up when using the control switch
- Mirror may move in other directions but not up
4. Step-by-Step Diagnosis
Check for blown fuses related to the mirror circuit.
Inspect the mirror connector and door harness for damage, corrosion, or loose pins.
Test the mirror motor by applying direct battery voltage to see if it operates.
Measure resistance and voltage at the mirror control switch and module.
If wiring and motor are good, suspect a faulty control switch or body ECU.
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, this is a low-severity issue. The mirror will not adjust upward, but the vehicle remains safe to drive.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether the fix involves wiring repair, switch replacement, or mirror motor replacement.