B1746 — Mirror Passenger Horizontal Switch Circuit Open #

Note: The description for DTC B1746 may vary depending on the vehicle manufacturer (OEM). Always refer to your specific vehicle’s service manual for the exact terminology.

• B1746: Mirror Passenger Horizontal Switch Circuit Open (Generic/OEMs)
• B1746: Right Mirror Horizontal Switch Circuit Open (Ford, Chrysler)
• B1746: Passenger Side Mirror Adjustment Switch Open (Toyota, Honda)

Summary of code B1746 #

B1746 indicates an open circuit in the electrical pathway that controls the horizontal (left/right) adjustment of the passenger side (right-side) mirror. What does “open circuit” mean? Simply put, it’s a break or disconnection somewhere in the wiring or at the switch, preventing electrical current from reaching its destination. This diagnostic trouble code (DTC) is flagged whenever the vehicle’s body control module (BCM) or door control module detects a fault in the signal from the passenger mirror adjustment switch. The result is a non-functioning right-side mirror adjustment, which can affect comfort and, in some cases, safety.

Common symptoms for code B1746 #

When B1746 is set, you’ll typically notice one or more clear signs, often related to your ability to adjust the passenger side mirror. These issues are usually more of an annoyance than a critical safety threat, but they can become a hassle over time. Symptoms may include:

• No response from the passenger side mirror when attempting horizontal (left/right) adjustment
• Mirror may adjust vertically (up/down), but not horizontally
• Mirror adjustment switch feels loose or unresponsive
• Possible door module warning or error message on the dashboard (vehicle dependent)
• In rare cases, mirror memory functions may be affected

Probable causes for code B1746 #

The most common causes for a B1746 code are related to an interruption in the circuit for the passenger mirror’s horizontal adjustment. Understanding the root causes helps ensure repairs are effective and not just guesswork. Here they are, ranked from most to least likely:

1. Faulty mirror horizontal adjustment switch (worn contacts or internal failure)
2. Broken, corroded, or disconnected wiring between the switch and the mirror motor
3. Damaged or loose connector at the switch or mirror assembly
4. Defective mirror actuator motor (specific to horizontal movement)
5. Faulty door control module (less common)

Step-by-step diagnosis for code B1746 #

A systematic approach saves time and prevents replacing parts unnecessarily. Here’s how a technician or advanced DIYer would typically diagnose B1746:

• Verify the code with a scan tool and clear any stored codes. Test the mirror adjustment to confirm symptoms.
• Visually inspect the mirror adjustment switch, wiring harness, and connectors for obvious signs of damage, corrosion, or disconnection.
• Test the switch function using a multimeter to check for continuity when the switch is pressed left/right.
• Check wiring continuity between the switch and the mirror actuator, looking for open or high-resistance circuits.
• Test the mirror actuator motor by applying direct power and ground to its horizontal adjustment pins (following OEM procedures).
• If all components test good, inspect the door control module for potential internal faults or communication issues.

Possible repairs for code B1746 #

The fix for B1746 always depends on the exact cause found during diagnosis. The goal is to restore full function to the passenger mirror adjustment. Typical repairs include:

• Replace the mirror adjustment switch if it fails continuity or shows internal wear
• Repair or replace damaged wiring or connectors between the switch, mirror, and control module
• Replace the mirror actuator motor (if the horizontal function is inoperative and wiring/switch are good)
• Secure or clean connectors to ensure proper contact
• Replace the door control module (only if all other components are confirmed good and module output is faulty)

Is it safe to drive with code B1746? #

Yes, you can continue driving with code B1746. This DTC does not affect engine or critical safety systems. However, the inability to adjust the passenger side mirror horizontally may hinder your ability to set mirrors for optimal visibility, which can be inconvenient or, in some scenarios, reduce safety when changing lanes. It’s advisable to repair the issue at your earliest convenience, especially if you regularly drive with multiple drivers or need to adjust mirrors frequently.

Vehicles most commonly affected by code B1746 #

While B1746 can appear on vehicles from many manufacturers, it’s more frequently reported on models with power mirrors and advanced door modules. The following vehicles are commonly associated with this code:

• Ford F-Series (F-150, F-250)
• Chrysler 300, Dodge Charger/Challenger
• Toyota Camry, Corolla
• Honda Accord, CR-V
• Jeep Grand Cherokee
• Nissan Altima, Maxima

Common mistakes & best practices for code B1746 #

Misdiagnosis often leads to unnecessary part replacements. To avoid wasting time and money, keep these points in mind:

• Don’t replace the entire mirror assembly without first testing the switch and wiring.
• Always check for broken or corroded wires in door harnesses, especially where wires flex with door movement.
• Use a wiring diagram to trace circuits—don’t guess which wire does what.
• Test the adjustment switch thoroughly; a failed switch is more common than a failed mirror motor.
• After repairs, always clear the code and verify full mirror operation before returning the vehicle to service.

Quick FAQ for code B1746 #

Here are answers to a couple of the most common questions asked about this trouble code:

• Q: Will this code cause my mirror to stop moving in all directions?
  A: Typically, only the horizontal (left/right) movement is affected. Vertical movement and mirror heating (if equipped) should still function unless there is a broader wiring issue.
• Q: Can I fix this myself?
  A: If you’re comfortable using basic tools and a multimeter, you can inspect connectors and wiring or swap out a faulty switch. However, some repairs (like module replacement or complex wiring repairs) are better left to a professional.