The diagnostic trouble code (DTC) B1698 indicates an issue within the vehicle's power mirror system, specifically related to the left (driver's side) mirror's upward adjustment function. This code suggests that the vehicle's computer detects a constant "high" signal from the mirror switch's "up" input, even when the switch is not being actively pressed. This can prevent the driver from properly adjusting the mirror and may indicate a wiring fault, a faulty switch, or a problem with the body control module (BCM).
Comprehensive Table: B1698 Mirror Switch L Up Input Stuck High
| Category | Description | Possible Causes |
|---|---|---|
| Definition | B1698 Diagnostic Trouble Code | Left (Driver's Side) Power Mirror Switch "Up" Input Circuit is stuck in a high voltage state. |
| Symptoms | Functional Issues | Mirror may move upwards uncontrollably, mirror may not move at all, inability to adjust mirror up/down using the switch, other electrical issues (related to the BCM in some cases). |
| Possible Causes | Wiring & Connections | Short to voltage in the "up" signal wire, open circuit in the "ground" wire, corroded or loose connectors, damaged wiring harness. |
| Switch | Faulty mirror switch internally shorting the "up" signal to voltage, damaged switch contacts. | |
| Body Control Module (BCM) | Faulty BCM driver circuit for the mirror control, internal BCM failure. (Less Common) | |
| Diagnostic Tools | Required Equipment | Multimeter, wiring diagrams for the specific vehicle make and model, scan tool capable of reading DTCs, possibly a test light. |
| Diagnostic Procedure | Initial Steps | Verify the DTC with a scan tool, inspect the mirror switch and wiring for obvious damage, check fuses related to the power mirror system. |
| Wiring Checks | Use a multimeter to check the continuity and voltage of the "up" signal wire, check for shorts to ground or voltage, inspect the wiring harness for damage. | |
| Switch Testing | Use a multimeter to test the switch for proper operation, verify the switch is not internally shorted. | |
| BCM Testing | (Typically requires advanced diagnostic skills) Check the BCM input and output signals for the mirror control, test the BCM driver circuit. | |
| Repair Strategies | Wiring Repair | Repair or replace damaged wiring, clean and tighten corroded connectors, repair shorts to voltage or ground. |
| Switch Replacement | Replace the faulty mirror switch with a new or known good switch. | |
| BCM Replacement/Reprogramming | (Requires specialized equipment and knowledge) Replace or reprogram the BCM. This is usually a last resort. | |
| Related DTCs | Common Codes | Other power mirror related codes (e.g., codes for other mirror directions, or the right-side mirror), BCM related codes, network communication codes. |
| Severity | Impact on Vehicle Operation | Driver may not be able to properly adjust the mirror, which can affect visibility and safety. In some cases, it can drain the battery if the mirror motor is constantly running. |
| Component Location | Physical Placement | Mirror switch is typically located on the driver's side door panel. The BCM is usually located under the dash or in the center console. The power mirror motor is inside the mirror housing. |
| Affected Systems | Vehicle Systems | Power mirror system, body control system. |
| Common Vehicle Makes | Susceptible Brands | This code is not specific to any particular vehicle make or model, but is more commonly found in vehicles with complex electrical systems. |
| Voltage Levels | Standard Voltages | Typically, a "high" signal is around 12 volts (battery voltage), and a "low" signal is close to 0 volts. The specific voltage levels may vary depending on the vehicle. |
| Circuit Type | Signal Circuit | The "up" signal wire is a signal circuit that carries information from the mirror switch to the BCM. |
| Ground Points | Crucial Grounds | Ensure the ground points for the mirror switch and BCM are clean and secure. A poor ground can cause a variety of electrical problems. |
| Fuse Location | Related Fuses | Check the owner's manual for the location of the fuse(s) related to the power mirror system. |
| Potential for Intermittent Issues | Intermittent problems are common in electrical systems. Wiggling the wiring harness or switch may reveal an intermittent issue. | |
| Advanced Diagnostics | Utilizing Oscilloscopes | An oscilloscope can be used to visualize the signal from the mirror switch and identify any anomalies. |
| Repair Difficulty | Skill Level Required | Repair difficulty can range from basic (checking fuses and connectors) to advanced (diagnosing BCM issues). |
| Safety Precautions | Important Considerations | Disconnect the battery before working on the electrical system to prevent electrical shock. |
Detailed Explanations
Definition: B1698 is a diagnostic trouble code indicating that the vehicle's computer has detected a constant "high" voltage signal on the "up" input circuit of the left (driver's side) power mirror switch. This implies the circuit is stuck in a state suggesting the "up" button is always pressed, even when it isn't.
Symptoms: The most obvious symptom is the inability to properly adjust the driver's side mirror. The mirror might move upwards uncontrollably, or it might be completely unresponsive to the "up" input. In some cases, the mirror might not move at all, or other related electrical issues could arise, especially if the BCM is involved.
Possible Causes: Wiring & Connections: A short to voltage in the "up" signal wire is a primary suspect. This means the wire is somehow making contact with a power source, causing it to constantly send a "high" signal. An open circuit in the ground wire can also cause this. Corroded or loose connectors can disrupt the signal flow, and a damaged wiring harness can expose wires and create shorts.
Possible Causes: Switch: A faulty mirror switch is another common cause. Internally, the switch could be shorting the "up" signal to a voltage source, mimicking a constant button press. Damaged switch contacts can also lead to erratic or incorrect signals.
Possible Causes: Body Control Module (BCM): While less frequent, a faulty BCM can also be responsible. The BCM controls various body functions, including power mirrors. A failure in the BCM's driver circuit for the mirror control, or an internal BCM failure, can cause the B1698 code.
Diagnostic Tools: A multimeter is essential for checking voltage and continuity in the wiring. Wiring diagrams specific to the vehicle are crucial for identifying the correct wires and connectors. A scan tool is needed to read and clear DTCs. A test light can also be helpful in identifying power and ground issues.
Diagnostic Procedure: Initial Steps: First, confirm the B1698 code with a scan tool. Then, visually inspect the mirror switch and its wiring for any obvious damage, such as frayed wires or broken connectors. Check the fuses related to the power mirror system to ensure they are not blown.
Diagnostic Procedure: Wiring Checks: Use a multimeter to check the continuity and voltage of the "up" signal wire. With the switch disconnected, check for shorts to ground or voltage on the wire leading to the BCM. Inspect the wiring harness for any signs of damage, such as cuts or abrasions.
Diagnostic Procedure: Switch Testing: Disconnect the mirror switch and use a multimeter to test its operation. Verify that the switch is not internally shorted by checking the resistance between the "up" terminal and other terminals when the switch is in the "off" position. A low resistance reading would indicate a short.
Diagnostic Procedure: BCM Testing: (Requires advanced diagnostic skills). This involves checking the BCM's input and output signals for the mirror control. You may need to test the BCM driver circuit using a specialized diagnostic tool or an oscilloscope. This is typically performed by a qualified technician.
Repair Strategies: Wiring Repair: Repair or replace any damaged wiring. Clean and tighten corroded connectors to ensure a good electrical connection. Address any shorts to voltage or ground by isolating and repairing the damaged wire.
Repair Strategies: Switch Replacement: If the switch is found to be faulty, replace it with a new or known good switch. Ensure the replacement switch is compatible with the vehicle.
Repair Strategies: BCM Replacement/Reprogramming: This is a last resort and requires specialized equipment and knowledge. Replacing or reprogramming the BCM should only be done by a qualified technician. Ensure the replacement BCM is properly programmed for the vehicle's specific configuration.
Related DTCs: Other power mirror related codes, such as codes for other mirror directions or the right-side mirror, may be present. BCM related codes or network communication codes can also indicate a more complex issue affecting multiple systems.
Severity: The severity of the B1698 code is moderate. The driver may not be able to properly adjust the mirror, which can impair visibility and safety. In rare cases, a continuously running mirror motor could drain the battery.
Component Location: The mirror switch is typically located on the driver's side door panel. The BCM is usually located under the dash or in the center console. The power mirror motor is located inside the mirror housing.
Affected Systems: The primary systems affected are the power mirror system and the body control system.
Common Vehicle Makes: The B1698 code is not specific to any particular vehicle make or model.
Voltage Levels: A "high" signal is typically around 12 volts (battery voltage), while a "low" signal is close to 0 volts.
Circuit Type: The "up" signal wire is a signal circuit that transmits information from the mirror switch to the BCM.
Ground Points: Ensure the ground points for the mirror switch and BCM are clean and secure. A poor ground can cause a variety of electrical problems.
Fuse Location: Check the owner's manual for the location of the fuse(s) related to the power mirror system.
Potential for Intermittent Issues: Intermittent electrical problems are common. Wiggling the wiring harness or switch may reveal an intermittent issue.
Advanced Diagnostics: Utilizing Oscilloscopes: An oscilloscope can be used to visualize the signal from the mirror switch and identify any anomalies, such as signal noise or dropouts.
Repair Difficulty: The repair difficulty can range from basic (checking fuses and connectors) to advanced (diagnosing BCM issues).
Safety Precautions: Always disconnect the battery before working on the electrical system to prevent electrical shock.
Frequently Asked Questions
What does the B1698 code mean? It means the vehicle's computer has detected a constant "high" voltage signal on the left mirror's "up" input circuit, suggesting the switch is always pressed.
What are the common symptoms of a B1698 code? The most common symptom is the inability to properly adjust the driver's side mirror up and down.
What could cause the B1698 code? Possible causes include a short to voltage in the wiring, a faulty mirror switch, or a problem with the BCM.
Can I fix the B1698 code myself? You can attempt basic troubleshooting, such as checking fuses and connectors, but more complex repairs may require a qualified technician.
How do I test the mirror switch? Disconnect the switch and use a multimeter to check for continuity and shorts between the terminals.
Conclusion
The B1698 code indicates a fault in the left power mirror's "up" input circuit. Diagnosing and repairing this issue involves systematically checking the wiring, switch, and potentially the BCM. Addressing this code ensures proper mirror functionality and contributes to safer driving.