B1718 - Power Folding Mirror Switch Input Circuit High

Introduction:

The diagnostic trouble code (DTC) B1718, "Power Folding Mirror Switch Input Circuit High," indicates a problem within the electrical circuit responsible for controlling the power folding mirrors in a vehicle. This code suggests that the vehicle's computer, often the Body Control Module (BCM), has detected an abnormally high voltage signal from the power folding mirror switch circuit, potentially preventing the mirrors from operating correctly. Addressing this issue promptly is crucial for restoring full functionality to the power folding mirrors and ensuring safe driving conditions.

Table: B1718 - Power Folding Mirror Switch Input Circuit High

Detailed Explanations:

Definition of B1718: The B1718 diagnostic trouble code signifies that the vehicle's computer system has detected an issue with the voltage signal coming from the power folding mirror switch circuit. Specifically, the voltage is higher than the expected range, indicating a potential fault in the wiring, switch, or related components.

System Affected: The power folding mirror system is the primary system affected. This system allows the driver to electrically fold the side mirrors inward, typically for navigating tight spaces or parking.

Affected Component: The components most likely affected are the power folding mirror switch itself, the wiring harness connecting the switch to the Body Control Module (BCM), any connectors within that circuit, and, in rare cases, the BCM itself. The power folding mirror motor can also be indirectly affected.

Common Symptoms: The most common symptom is the power folding mirrors not working at all. Other symptoms include intermittent operation of the mirrors, the mirrors being stuck in either the folded or unfolded position, and the presence of the B1718 error code when the vehicle's computer is scanned.

Less Common Symptoms: In rare cases, the faulty circuit could potentially cause other minor electrical issues. A significant short to voltage could also lead to a slight battery drain, though this is less common.

Open Circuit in the Signal Wire: An open circuit means there's a break in the wire carrying the signal from the switch to the BCM. This prevents the proper voltage signal from reaching the BCM, leading to the "high" reading because the BCM expects a change in voltage based on the switch position.

Short to Voltage in the Signal Wire: A short to voltage occurs when the signal wire comes into contact with another wire carrying a higher voltage. This forces the voltage in the signal wire to be higher than intended, triggering the B1718 code.

Faulty Power Folding Mirror Switch: A malfunctioning switch can send an incorrect voltage signal to the BCM, or no signal at all. This can be due to internal damage, corrosion, or a broken contact within the switch.

Corroded or Damaged Connector(s): Corroded or damaged connectors can impede the flow of electrical current, leading to inaccurate voltage readings. Moisture, dirt, and physical damage can all contribute to connector problems.

Damaged Wiring Harness: The wiring harness protects and organizes the wires connecting the switch to the BCM. Damage to the harness, such as cuts, abrasions, or pinched wires, can cause shorts, opens, or other electrical issues.

Defective Body Control Module (BCM): Although less common, a faulty BCM can misinterpret or incorrectly process the signal from the power folding mirror switch. This is often a last resort diagnosis after ruling out other potential causes.

Faulty Power Folding Mirror Motor (Indirectly): While the motor itself isn't directly part of the switch input circuit, a shorted or malfunctioning motor can sometimes draw excessive current, potentially affecting the voltage readings within the circuit and contributing to the B1718 code.

Water Intrusion into Connectors or Wiring: Water intrusion can cause corrosion and short circuits, leading to erratic voltage readings and triggering the B1718 code.

Rodent Damage to Wiring: Rodents can chew on vehicle wiring, causing damage that leads to shorts, opens, or other electrical problems.

Visually Inspect Wiring and Connectors: Carefully examine the wiring and connectors associated with the power folding mirror switch for any signs of damage, such as frayed wires, corroded terminals, or loose connections.

Check for Blown Fuses: A blown fuse in the power mirror system can indicate a short circuit or other electrical problem. Replace any blown fuses with the correct amperage rating.

Verify Battery Voltage: Ensure the vehicle's battery voltage is within the normal range. Low battery voltage can sometimes cause false error codes.

Read and Clear DTCs: Use a scan tool to read any stored diagnostic trouble codes (DTCs) in the vehicle's computer system. Clear the codes and see if the B1718 code returns.

Monitor Power Folding Mirror Switch Input Voltage: Use a scan tool to monitor the voltage signal from the power folding mirror switch as the switch is activated. This can help identify whether the switch is sending the correct signals.

Test the Power Folding Mirror Switch: Use a multimeter to test the power folding mirror switch for proper resistance and continuity. This will verify whether the switch is functioning correctly.

Perform a Voltage Drop Test: A voltage drop test can help identify areas of excessive resistance in the wiring harness. This involves measuring the voltage drop across different sections of the wiring while the circuit is active.

Check the Power Folding Mirror Motor Operation: Ensure the power folding mirror motor is functioning properly. If the motor is drawing excessive current or is shorted, it can affect the voltage readings in the switch circuit.

Use a Multimeter to Check for Shorts to Voltage and Opens: Use a multimeter to carefully check the wiring harness for shorts to voltage (unintended contact with a voltage source) and opens (breaks in the circuit).

Check the BCM for Proper Operation and Grounding: Verify that the BCM is properly grounded and functioning correctly. A faulty BCM can misinterpret or incorrectly process the signal from the power folding mirror switch.

Replacing a Faulty Power Folding Mirror Switch: If the power folding mirror switch is found to be defective, replacing it with a new switch is the most common solution.

Repairing or Replacing Damaged Wiring or Connectors: If the wiring or connectors are damaged, repair or replace them as necessary. Ensure that all connections are secure and properly insulated.

Replacing a Blown Fuse: If a fuse related to the power mirror system is blown, replace it with a new fuse of the correct amperage rating.

Replacing the Body Control Module (BCM): Replacing the BCM is a less common solution, but it may be necessary if the BCM is determined to be faulty. This should only be done after all other potential causes have been ruled out.

Repairing or Replacing the Power Folding Mirror Motor: If the power folding mirror motor is indirectly related to the circuit problem, repairing or replacing it may be necessary.

Related DTCs: Other DTCs related to the power mirror system, such as B1717 (Power Folding Mirror Switch Input Circuit Low) or codes related to mirror motor control, may also be present. Addressing these codes in conjunction with B1718 can help resolve the overall issue.

Circuit Type: The power folding mirror switch input circuit is typically a low-current signal circuit.

Voltage Range (Expected): The expected voltage range varies depending on the vehicle manufacturer and model. A scan tool is crucial for determining the correct voltage readings for the switch in different positions. Typically, there will be a low voltage in one position and a higher voltage in another.

Location of Components: The power folding mirror switch is typically located on the door panel, within easy reach of the driver. The Body Control Module (BCM) is usually located under the dashboard or in the center console.

Frequently Asked Questions:

• What does the B1718 code mean? It means the vehicle's computer has detected a higher-than-expected voltage signal from the power folding mirror switch circuit.

• Can I fix this myself? Potentially, if you have experience with automotive electrical systems and a multimeter. However, professional diagnosis is recommended for accurate troubleshooting.

• How serious is this code? While it may not directly affect vehicle safety, it can prevent the power folding mirrors from working, which can be inconvenient.

• What are the most common causes? The most common causes are a faulty power folding mirror switch, damaged wiring, or corroded connectors.

• Do I need to replace the BCM? Replacing the BCM is rarely necessary. It should only be considered after all other potential causes have been ruled out.

Conclusion:

The B1718 code indicates a problem with the power folding mirror switch input circuit. Thorough diagnosis, starting with visual inspection and component testing, is essential for identifying the root cause. Addressing the issue promptly will restore functionality to the power folding mirrors and ensure a more convenient driving experience.