B1742 — Mirror Passenger Vertical Switch Circuit Open #

The description of this code may vary by manufacturer. Always refer to your vehicle’s OEM documentation for the most accurate wording.

• Mirror Passenger Vertical Switch Circuit Open (Chrysler, Ford, Toyota)
• Right Mirror Vertical Switch Circuit Open (Honda, Nissan)
• Passenger Side Mirror Up/Down Switch Circuit Open (GM, Hyundai)

Summary for code B1742 #

B1742 is a diagnostic trouble code (DTC) related to the electrical circuit controlling the vertical adjustment switch for the passenger side mirror. In simpler terms, this code indicates that the vehicle’s onboard computer (usually the Body Control Module, or BCM) has detected an “open” (interruption) in the circuit that moves the passenger mirror up and down. This disruption prevents the normal adjustment of the mirror, which can be inconvenient and sometimes pose a safety issue. The problem can stem from a faulty switch, damaged wiring, or, in rarer cases, a failed mirror actuator or control module. Understanding the root cause is essential for a proper and lasting repair.

Common symptoms for code B1742 #

When your vehicle sets the B1742 code, you’ll usually notice issues related to the passenger side mirror adjustment. Sometimes, the only clue is a warning light or a fault message on the dashboard. In other cases, the symptoms are more obvious and may affect daily driving convenience.

• Passenger side mirror won’t move up or down
• No response from the passenger side mirror switch when trying to adjust vertically
• Intermittent or slow vertical movement of the passenger mirror
• Warning light or message related to mirror adjustment system
• Possible loss of memory function for the mirror (if equipped)

Most common causes for code B1742 #

The majority of B1742 cases are tied to issues in the wiring or the switch itself. However, it’s important not to overlook other possibilities, especially if the problem persists after initial repairs.

1. Faulty passenger mirror vertical adjustment switch: The switch that controls the up/down movement may have worn contacts or internal failure.
2. Open or damaged wiring: Broken wires, poor connections, or corrosion in the harness between the switch and the mirror actuator.
3. Defective mirror actuator: The small electric motor inside the mirror may have failed or lost connection.
4. Faulty Body Control Module (BCM): Rare, but possible—especially if other electrical issues are present.
5. Blown fuse or poor ground connection: Sometimes overlooked, these can cause open circuits.

Step-by-step diagnostic for code B1742 #

Diagnosing B1742 requires a methodical approach to avoid unnecessary part replacements. Here’s a proven workflow that balances efficiency and thoroughness:

• 1. Scan for related codes: Use a professional scan tool to check for other DTCs, especially those related to the mirror or door modules.
• 2. Test mirror switch operation: Manually operate the passenger mirror switch and listen for any clicking or movement in the mirror motor.
• 3. Inspect wiring and connectors: Carefully examine the harness and connectors between the switch, BCM, and mirror for breaks, corrosion, or loose pins.
• 4. Measure voltage and continuity: Use a multimeter to verify power and ground at the switch, and check continuity of the vertical adjustment circuit.
• 5. Bypass or jumper test: Temporarily bypass the switch to see if the mirror actuator responds, confirming whether the issue is with the switch or downstream components.
• 6. Test the actuator: Directly supply power to the mirror’s vertical actuator to check for internal failure.
• 7. Inspect the BCM (if all else checks out): If wiring, switch, and actuator are good, further tests on the BCM or related modules may be necessary.

Possible repairs for code B1742 #

The most effective fix for B1742 depends on identifying the specific cause. Here’s how each scenario is typically addressed:

• Replace the passenger mirror vertical switch if it fails continuity or function tests.
• Repair or replace damaged wiring and clean or tighten any corroded or loose connectors in the mirror wiring harness.
• Replace the mirror actuator if it does not respond to direct power or shows signs of internal failure.
• Replace or reprogram the BCM only after ruling out other causes (rare, but possible with module-related faults).
• Replace blown fuse or repair ground connection if electrical testing reveals these faults.

Can you drive with code B1742? #

Yes, you can generally continue driving with code B1742, as it does not affect the vehicle’s core performance or safety systems. However, the inability to adjust the passenger side mirror can reduce visibility and increase the risk of blind spots, especially if multiple drivers use the vehicle. For optimal safety and convenience, it’s best to address the issue as soon as possible.

Vehicles most commonly affected by code B1742 #

While B1742 is a universal OBD-II code, it appears most frequently in vehicles with advanced power mirror systems. Some OEMs design their mirror circuits with additional switches or memory functions, which can make them more susceptible to open circuit faults.

• Ford (Focus, Fusion, Explorer, F-150 series)
• Chrysler/Jeep/Dodge (Grand Cherokee, 300, Ram)
• Toyota (Camry, RAV4, Highlander)
• Honda (Civic, Accord, CR-V)
• GM (Chevrolet Silverado, GMC Sierra, Cadillac models)
• Nissan (Altima, Rogue, Pathfinder)
• Hyundai/Kia (Sonata, Elantra, Santa Fe)

Frequent mistakes & best practices for code B1742 #

It’s not uncommon for both DIYers and technicians to misdiagnose or skip crucial steps when dealing with B1742. Here are some pitfalls and tips for a successful repair:

• Replacing the mirror actuator without first testing the switch or wiring
• Overlooking simple wiring issues—broken wires in the door harness are a common culprit
• Forgetting to test ground connections and fuses before ordering expensive parts
• Neglecting to clear codes and retest the system after repairs
• Best practice: Always use the vehicle’s wiring diagram and OEM procedures for precise diagnosis

Quick FAQ for code B1742 #

No time to read the whole article? Here are the fast answers to the most common questions:

• Q: Will B1742 cause my car to fail inspection?
  A: Typically, no. This code does not trigger a check engine light or emissions fault, but may be flagged if a full system scan is performed during inspection.
• Q: Can I fix B1742 myself?
  A: If you’re comfortable with basic electrical testing and working with trim panels, you can often diagnose and repair a switch or wiring fault yourself. For actuator or module replacement, consider professional assistance.