The B1742 diagnostic trouble code (DTC) signals a problem within the electrical circuit controlling the vertical movement of the passenger-side power mirror. This fault indicates that the vehicle's computer (typically the Body Control Module or BCM) has detected an open circuit in the signal path from the mirror switch to the mirror motor responsible for vertical adjustments. Resolving this issue ensures proper mirror functionality, improving visibility and driving safety.
This code means the mirror cannot be adjusted up or down, which can significantly hinder the driver's ability to see properly, especially in changing traffic conditions. Prompt diagnosis and repair are essential for both safety and convenience.
| Component/Aspect | Description | Potential Causes |
|---|---|---|
| Definition | DTC B1742 indicates an open circuit in the signal path for the passenger-side mirror's vertical movement. | Broken or damaged wiring, corroded connectors, faulty mirror switch, faulty mirror motor, BCM malfunction. |
| Affected System | Passenger-side power mirror vertical adjustment circuit. | Power mirror system, Body Control Module (BCM), associated wiring harnesses and connectors. |
| Symptoms | Passenger-side mirror cannot be adjusted vertically (up or down). | Inability to adjust the passenger-side mirror up or down, diagnostic trouble code B1742 stored in the vehicle's ECM/BCM. |
| Diagnostic Tools | Multimeter, wiring diagram, scan tool. | Multimeter, circuit tester, wiring diagram, scan tool with live data capabilities. |
| Troubleshooting Steps | Visual inspection, circuit testing, component testing, BCM diagnostics. | Check wiring and connectors, test the mirror switch, test the mirror motor, check BCM functionality. |
| Wiring Diagram Reference | Vehicle-specific wiring diagram. | Consult the vehicle's repair manual or online database for the correct wiring diagram. |
| Connector Locations | Typically located in the door panel, dashboard, and near the BCM. | Refer to the vehicle's service manual for specific connector locations. |
| Mirror Switch Resistance | Should have specific resistance values when activated in up/down positions. | Use a multimeter to measure resistance in the up and down positions. Refer to the service manual for specifications. |
| Mirror Motor Voltage | Should receive voltage when the switch is activated. | Use a multimeter to check for voltage at the motor connector when the switch is activated. |
| BCM Functions | Receives signals from the mirror switch and controls the mirror motor. | The BCM processes the input from the switch and sends the appropriate signals to the mirror motor to initiate movement. |
| Common Failure Points | Wiring within the door jamb, mirror switch, mirror motor, and BCM connectors. | Frequent opening and closing of the door can damage wiring in the door jamb. |
| Related DTCs | Other mirror-related DTCs (horizontal adjustment), BCM communication errors. | These codes may provide additional clues about the root cause of the problem. |
| Repair Procedures | Wire repair, connector cleaning/replacement, switch replacement, motor replacement, BCM reprogramming. | Repair or replace damaged wiring, clean or replace corroded connectors, replace faulty switch or motor, reprogram BCM. |
| Safety Precautions | Disconnect the battery before working on electrical components. | Always disconnect the battery to prevent electrical shock or damage to vehicle components. |
| Estimated Repair Cost | Varies depending on the failed component and labor rates. | The cost can range from a simple wire repair to a full BCM replacement. |
| Time to Diagnose | 1-3 hours depending on experience and complexity of the issue. | Thorough diagnosis is critical to avoid unnecessary parts replacement. |
| Preventative Measures | Inspect wiring and connectors regularly, avoid slamming doors, protect from water damage. | Regular maintenance can help prevent future issues with the power mirror system. |
| Aftermarket Considerations | Aftermarket mirrors or switches can cause compatibility issues. | Ensure that any aftermarket components are compatible with the vehicle's electrical system. |
| Impact on Safety | Impaired visibility can increase the risk of accidents. | A properly functioning mirror is essential for safe driving. |
| Impact on Convenience | Inability to adjust the mirror can be inconvenient and frustrating. | Power mirrors provide convenient adjustment for drivers of different heights and preferences. |
| BCM Reprogramming Tools | Specialized scan tools required for BCM reprogramming. | BCM reprogramming may be necessary after replacing the BCM or updating its software. |
| Open Circuit Testing | Using a multimeter in resistance mode to identify breaks in the wiring. | An open circuit will show infinite resistance on the multimeter. |
| Load Testing | Using a test light or voltmeter to check for voltage drop under load. | Load testing can reveal weak circuits that may not be apparent during simple voltage testing. |
| CAN Bus Communication | The BCM communicates with other modules via the CAN bus. | Problems with the CAN bus can affect the functionality of various systems, including the power mirrors. |
| Grounding Points | Check for proper grounding of the mirror motor and BCM. | Poor grounding can cause intermittent electrical problems. |
| Fuse Location | Identify and check the fuse for the power mirror system. | A blown fuse can cause a complete loss of power to the mirror system. |
| Wire Harness Routing | Ensure the wire harness is properly routed and not pinched or damaged. | Incorrect routing can lead to chafing and damage to the wiring. |
| Door Jamb Boot | Inspect the wiring inside the door jamb boot for damage. | The door jamb boot is a common area for wiring to break due to repeated flexing. |
| Mirror Motor Internal Resistance | Measure the resistance of the mirror motor windings. | High or infinite resistance indicates a faulty motor. |
| Switch Contact Corrosion | Inspect the switch contacts for corrosion or damage. | Corroded contacts can prevent proper electrical flow. |
Detailed Explanations
Definition: The B1742 code indicates that the vehicle's computer has detected a break in the electrical circuit that controls the vertical movement of the passenger-side power mirror. This means there is an interruption in the flow of electricity between the mirror switch and the mirror motor.
Affected System: The primary system affected is the passenger-side power mirror vertical adjustment circuit. This includes the mirror switch, the wiring connecting the switch to the mirror motor, the mirror motor itself, and the Body Control Module (BCM), which controls the system.
Symptoms: The most obvious symptom is the inability to adjust the passenger-side mirror vertically (up or down). The diagnostic trouble code B1742 will also be stored in the vehicle's computer, which can be read using a scan tool.
Diagnostic Tools: Several tools are required for diagnosing this issue. A multimeter is essential for testing the continuity and voltage of the circuit. A wiring diagram specific to the vehicle is crucial for understanding the circuit layout and identifying the correct wires to test. A scan tool is used to read the B1742 code and potentially access live data from the BCM.
Troubleshooting Steps: The troubleshooting process involves several steps. First, a visual inspection of the wiring and connectors is performed to look for obvious signs of damage or corrosion. Next, circuit testing is conducted using a multimeter to identify the location of the open circuit. Component testing involves testing the mirror switch and mirror motor to ensure they are functioning correctly. Finally, BCM diagnostics may be necessary to rule out a problem with the vehicle's computer.
Wiring Diagram Reference: A vehicle-specific wiring diagram is indispensable. These diagrams can be found in the vehicle's repair manual or online databases. The diagram will show the exact routing of the wires, the location of connectors, and the pinouts of the components.
Connector Locations: Connectors are typically located in the door panel, dashboard, and near the BCM. Refer to the vehicle's service manual for specific connector locations, as they can vary depending on the make and model.
Mirror Switch Resistance: The mirror switch should have specific resistance values when activated in the up and down positions. Use a multimeter to measure the resistance in these positions. Refer to the service manual for the correct specifications. An infinite resistance reading indicates an open circuit within the switch.
Mirror Motor Voltage: The mirror motor should receive voltage when the switch is activated. Use a multimeter to check for voltage at the motor connector when the switch is activated. The absence of voltage indicates a problem in the circuit between the switch and the motor.
BCM Functions: The BCM receives signals from the mirror switch and controls the mirror motor. It processes the input from the switch and sends the appropriate signals to the motor to initiate movement.
Common Failure Points: Common failure points include wiring within the door jamb, the mirror switch, the mirror motor, and the BCM connectors. The wiring within the door jamb is particularly susceptible to damage due to the frequent opening and closing of the door.
Related DTCs: Other mirror-related DTCs (such as those related to horizontal adjustment) or BCM communication errors may provide additional clues about the root cause of the problem.
Repair Procedures: Repair procedures may include wire repair, connector cleaning or replacement, switch replacement, motor replacement, or BCM reprogramming. The specific repair required will depend on the location and nature of the fault.
Safety Precautions: Always disconnect the battery before working on electrical components to prevent electrical shock or damage to vehicle components.
Estimated Repair Cost: The estimated repair cost can vary depending on the failed component and labor rates. A simple wire repair may be relatively inexpensive, while a full BCM replacement can be significantly more costly.
Time to Diagnose: The time required to diagnose the issue can range from 1 to 3 hours, depending on experience and the complexity of the problem. Thorough diagnosis is critical to avoid unnecessary parts replacement.
Preventative Measures: Regular inspection of wiring and connectors, avoiding slamming doors, and protecting the system from water damage can help prevent future issues.
Aftermarket Considerations: Aftermarket mirrors or switches can cause compatibility issues. Ensure that any aftermarket components are compatible with the vehicle's electrical system.
Impact on Safety: Impaired visibility due to a malfunctioning mirror can increase the risk of accidents.
Impact on Convenience: The inability to adjust the mirror can be inconvenient and frustrating, especially for drivers of different heights.
BCM Reprogramming Tools: Specialized scan tools are required for BCM reprogramming. This may be necessary after replacing the BCM or updating its software.
Open Circuit Testing: Use a multimeter in resistance mode to identify breaks in the wiring. An open circuit will show infinite resistance on the multimeter.
Load Testing: Use a test light or voltmeter to check for voltage drop under load. This can reveal weak circuits that may not be apparent during simple voltage testing.
CAN Bus Communication: The BCM communicates with other modules via the CAN bus. Problems with the CAN bus can affect the functionality of various systems, including the power mirrors.
Grounding Points: Check for proper grounding of the mirror motor and BCM. Poor grounding can cause intermittent electrical problems.
Fuse Location: Identify and check the fuse for the power mirror system. A blown fuse can cause a complete loss of power to the mirror system. Consult the vehicle's owner's manual or service manual for fuse location.
Wire Harness Routing: Ensure the wire harness is properly routed and not pinched or damaged. Incorrect routing can lead to chafing and damage to the wiring.
Door Jamb Boot: Inspect the wiring inside the door jamb boot for damage. The door jamb boot is a common area for wiring to break due to repeated flexing.
Mirror Motor Internal Resistance: Measure the resistance of the mirror motor windings. High or infinite resistance indicates a faulty motor.
Switch Contact Corrosion: Inspect the switch contacts for corrosion or damage. Corroded contacts can prevent proper electrical flow.
Frequently Asked Questions
What does the B1742 code mean? It indicates an open circuit in the passenger-side mirror's vertical adjustment circuit, meaning there's a break in the electrical path.
What are the symptoms of a B1742 code? The passenger-side mirror cannot be adjusted up or down.
What could be causing the B1742 code? Possible causes include broken wiring, a faulty mirror switch, or a defective mirror motor.
Can I fix the B1742 code myself? With proper tools and knowledge of electrical systems, you might be able to diagnose and repair the issue. However, professional diagnosis and repair is often recommended.
How do I test the mirror switch? Use a multimeter to check for continuity when the switch is activated in the up and down positions.
Conclusion
The B1742 code signifies a break in the electrical circuit controlling the passenger-side mirror's vertical movement, leading to impaired mirror adjustment. Thoroughly inspect wiring, test components, and consult wiring diagrams to pinpoint and resolve the open circuit, ensuring safe and convenient operation of the power mirror system.