B1782 — Mirror Passenger Up Circuit Failure #

Note: The wording for this DTC (Diagnostic Trouble Code) may vary depending on the vehicle manufacturer.

• Mirror Passenger Up Circuit Failure (Toyota, Lexus, Scion)
• Passenger Side Mirror Up Movement Circuit Malfunction (Ford)
• Right Door Mirror Up Control Circuit Error (Nissan, Infiniti)
• Power Mirror Up Circuit Fault – Passenger Side (General Motors, Chrysler)

Summary of DTC B1782 #

The B1782 code indicates a malfunction in the electrical circuit responsible for moving the passenger side (right side) mirror upward. This code is stored by the Body Control Module (BCM) or Door Control Module when it detects an open, short, or abnormal voltage/resistance in the mirror’s up-movement circuit. The up-movement circuit is part of the power mirror system, enabling drivers to adjust the mirror for optimal rear visibility. A failure here can impact both comfort and safety, as proper mirror positioning is crucial for safe driving. While this fault rarely disables your vehicle, it can be inconvenient and should be addressed promptly.

Common Symptoms for Code B1782 #

When the B1782 code is present, you may notice issues with the passenger side mirror’s adjustability. In some cases, the malfunction may be intermittent, depending on the underlying cause. Symptoms typically include:

• Passenger side mirror does not move up when using the adjustment switch.
• Mirror may move in other directions (left, right, down) but not up.
• Clicking or no sound at all from the mirror motor when attempting upward adjustment.
• Dashboard warning light or DTC notification (if supported by the vehicle).
• Sometimes, all mirror controls on the passenger side become non-responsive.

Probable Causes of B1782 (Most to Least Common) #

Several factors can trigger the B1782 code. These range from simple electrical issues to component failures. The causes are listed below in order of likelihood:

1. Faulty passenger-side mirror motor (up circuit specifically)
2. Damaged or corroded wiring or connectors in the mirror up circuit
3. Defective mirror control switch on the driver or passenger door
4. Short to ground or open circuit in the up control wire
5. Malfunctioning Body Control Module (BCM) or Door Control Module (rare)
6. Poor ground connection at the mirror or door harness

Step-by-Step Diagnosis for Code B1782 #

Diagnosing B1782 involves a systematic approach, starting with basic checks and moving toward more involved electrical testing. Here’s how a competent technician or an experienced DIYer would proceed:

• Verify the code with an OBD-II/EOBD scan tool and record freeze frame data.
• Operate the mirror controls to confirm that only the up movement (and not other directions) is affected.
• Inspect the mirror switch for physical damage or signs of wear.
• Check the wiring harness between the door and the mirror for visible damage, pinched wires, or corrosion, especially at the door hinge area.
• Test the mirror motor by supplying power and ground directly to the up circuit (following OEM safety procedures) to see if it works independently of the switch and vehicle wiring.
• Use a multimeter to check continuity and voltage in the up circuit from the switch to the mirror.
• Inspect connectors for bent pins, corrosion, or loose fit at both the switch and the mirror ends.
• If all else checks out, consider BCM or door module diagnostics as per the vehicle’s OEM service manual.

Possible Repairs for Code B1782 #

Depending on the diagnosis, the fix for B1782 may be straightforward or require component replacement. Here are the most effective repair options:

• Replace the faulty mirror motor if it fails direct power testing.
• Repair or replace damaged wiring or connectors in the mirror up circuit.
• Replace the mirror control switch if internal failure is detected.
• Clean or tighten ground connections related to the mirror circuit.
• In rare cases, replace or reprogram the Body Control Module or Door Control Module after verifying it is at fault.

Is It Safe to Drive With Code B1782? #

Yes, with limitations. Code B1782 does not affect critical engine or brake systems, so your vehicle will remain drivable. However, the inability to adjust the passenger side mirror upward can create blind spots and reduce safety, especially when changing lanes or parking. For your comfort and safety, it’s best to address the issue soon and avoid extended driving with a misaligned mirror.

Vehicles Most Commonly Affected by B1782 #

While B1782 can appear on any vehicle with power mirrors, it is most frequently reported on the following models:

• Toyota Camry, Corolla, RAV4, Highlander
• Lexus ES, IS, RX series
• Ford F-150, Focus, Explorer
• Nissan Altima, Maxima, Rogue
• Chevrolet Silverado, Malibu, Equinox
• Chrysler 300, Pacifica, Dodge Charger

Common Mistakes & Best Practices for Code B1782 #

Misdiagnosis of B1782 can lead to unnecessary part replacements and frustration. To avoid costly errors and fix the issue efficiently, keep the following in mind:

• Don’t replace the mirror motor or switch before verifying wiring integrity—damaged wires at the door jamb are a common culprit.
• Always check for corrosion at connectors, especially in humid or coastal regions.
• Follow OEM wiring diagrams for accurate troubleshooting; wire colors and pinouts may vary.
• Clear the code only after repairs and verify proper mirror function before closing up panels.
• Document your findings for future reference or warranty purposes.

Code B1782 FAQ #

Q: Can a blown fuse cause code B1782?
A: While a blown fuse can disable all power mirror functions, B1782 specifically points to an up circuit problem. If all mirror movements are dead, check the fuse first; if only up is affected, focus on the up circuit wiring or motor.

Q: Will disconnecting the battery clear B1782?
A: Disconnecting the battery may temporarily clear the code from some modules, but the code will return if the underlying issue is not repaired. Always fix the actual fault before clearing codes.