This article delves into the complexities of the B3702 diagnostic trouble code (DTC), specifically focusing on "Intermittent Wiper Delay Input Circuit Low (BCM)." This code signifies a problem within the circuit responsible for controlling the delay function of your vehicle's intermittent wipers, and the Body Control Module (BCM) is the central processor detecting the fault. Understanding the causes, symptoms, and potential solutions is crucial for diagnosing and resolving this issue, ensuring safe and reliable operation of your windshield wipers.

Comprehensive Breakdown of the B3702 DTC

Topic Description Potential Implications
DTC Definition Intermittent Wiper Delay Input Circuit Low (BCM) indicates that the Body Control Module (BCM) has detected a voltage signal in the intermittent wiper delay input circuit that is below the expected or programmed threshold. Malfunctioning intermittent wipers, erratic wiper operation, inability to adjust wiper delay, potential misdiagnosis of wiper motor failure.
Affected Circuit The circuit connecting the wiper switch (specifically the delay setting control) to the Body Control Module (BCM). This circuit carries the signal representing the desired delay setting. Faulty wiper switch, damaged wiring harness, corroded connectors, malfunctioning BCM.
Body Control Module (BCM) The BCM is an electronic control unit responsible for managing various body functions, including lighting, power windows, door locks, and, importantly, windshield wipers. It interprets the signal from the wiper switch and controls the wiper motor accordingly. Incorrect wiper operation, failure of other BCM-controlled functions (though less likely directly related to this specific code), potential need for BCM reprogramming or replacement.
Common Causes Faulty Wiper Switch: The switch itself may be defective, sending an incorrect or intermittent signal. Wiring Issues: Damaged, shorted, or corroded wiring in the circuit between the wiper switch and the BCM. Connector Problems: Corroded or loose connectors can disrupt the signal flow. BCM Malfunction: In rare cases, the BCM itself may be faulty. Intermittent wiper failure, erratic wiper operation, complete wiper failure (less common), potential for electrical shorts and further damage.
Symptoms Intermittent wipers not working. Wipers only working on high or low speed. Inability to adjust the delay between wiper sweeps. Wipers operating continuously, regardless of switch position. Erratic or unpredictable wiper behavior. Check Engine Light (CEL) may or may not be illuminated. Reduced visibility in inclement weather, potential safety hazard, driver frustration, potential for damage to wiper motor and linkage.
Diagnostic Steps 1. Visual Inspection: Check wiring, connectors, and the wiper switch for any signs of damage or corrosion. 2. Wiper Switch Testing: Use a multimeter to test the wiper switch for proper continuity and resistance in each position. 3. Circuit Testing: Check the wiring between the wiper switch and the BCM for shorts, opens, and proper voltage. 4. BCM Testing: If other tests are inconclusive, the BCM may need to be tested by a qualified technician using specialized diagnostic equipment. Wasted time and effort on incorrect repairs, potential for further damage to electrical system, unnecessary replacement of parts.
Possible Solutions Replace faulty wiper switch. Repair or replace damaged wiring or connectors. Clean corroded connectors. Reprogram or replace the BCM (as a last resort, after thorough diagnosis). Restoration of proper wiper function, improved visibility in inclement weather, enhanced safety.
Tools Required Multimeter, wiring diagram for the specific vehicle, basic hand tools (screwdrivers, pliers, wire strippers), scan tool (optional, for reading and clearing DTCs). Difficulty in diagnosing and repairing the problem, potential for damage to electrical components.
Related DTCs B3701 (Intermittent Wiper Delay Input Circuit High), B3703 (Wiper Motor Relay Control Circuit Malfunction), other DTCs related to the BCM or wiper system. Misdiagnosis of the problem, overlooking other related issues in the wiper system.

Detailed Explanations

DTC Definition: The B3702 code signals that the BCM has detected a low voltage condition in the circuit responsible for receiving the delay setting signal from the wiper switch. This "low" condition means the voltage is lower than the expected range programmed into the BCM's memory. This discrepancy triggers the DTC and potentially affects the proper functioning of the intermittent wipers.

Affected Circuit: This circuit is the communication pathway between the wiper switch and the BCM. It specifically carries the information regarding the desired delay setting for the intermittent wiper function. This circuit is crucial for the BCM to understand how often the wipers should sweep the windshield.

Body Control Module (BCM): The BCM is a central computer that controls numerous electrical functions within the vehicle's body. It receives inputs from various sensors and switches, processes the information, and then controls outputs like lights, door locks, and, in this case, the windshield wipers. The BCM's interpretation of the wiper switch signal determines the wiper motor's operation.

Common Causes:

  • Faulty Wiper Switch: The wiper switch is the most common culprit. Internal wear or damage can cause it to send an incorrect or weak signal to the BCM.
  • Wiring Issues: Damaged wiring, such as cuts, breaks, or shorts to ground, can disrupt the signal flow and cause a low voltage condition. Corrosion can also increase resistance in the circuit, leading to a voltage drop.
  • Connector Problems: Corroded or loose connectors can prevent a proper electrical connection, hindering the signal from reaching the BCM.
  • BCM Malfunction: While less frequent, a faulty BCM can misinterpret the signal or have internal issues that cause it to incorrectly detect a low voltage condition.

Symptoms:

  • Intermittent wipers not working: The wipers may not function at all in the intermittent mode.
  • Wipers only working on high or low speed: The intermittent function is bypassed, and the wipers only operate on the constant high or low speed settings.
  • Inability to adjust the delay between wiper sweeps: The delay adjustment knob on the wiper switch has no effect.
  • Wipers operating continuously, regardless of switch position: In some cases, a short circuit can cause the wipers to run continuously.
  • Erratic or unpredictable wiper behavior: The wipers may sweep intermittently at random intervals.
  • Check Engine Light (CEL) may or may not be illuminated: The CEL is not always triggered by this code, as it primarily affects body functions rather than engine performance.

Diagnostic Steps:

  1. Visual Inspection: Begin by carefully inspecting the wiring harness, connectors, and the wiper switch for any obvious signs of damage, corrosion, or loose connections. Pay close attention to the wiring near the wiper motor and the BCM.
  2. Wiper Switch Testing: Use a multimeter to test the wiper switch for proper continuity and resistance in each position. Refer to the vehicle's wiring diagram to identify the correct terminals to test.
  3. Circuit Testing: Check the wiring between the wiper switch and the BCM for shorts to ground, opens (breaks in the wire), and proper voltage. Use a multimeter and the vehicle's wiring diagram to perform these tests.
  4. BCM Testing: If the previous tests are inconclusive, the BCM may need to be tested by a qualified technician using specialized diagnostic equipment. This usually involves checking the BCM's inputs and outputs and verifying its internal functionality.

Possible Solutions:

  • Replace faulty wiper switch: If the wiper switch is found to be defective, replacing it is the most straightforward solution.
  • Repair or replace damaged wiring or connectors: Repair any damaged wiring by splicing and soldering new sections of wire. Replace corroded or damaged connectors.
  • Clean corroded connectors: Clean corroded connectors with a wire brush or electrical contact cleaner. Apply dielectric grease to prevent future corrosion.
  • Reprogram or replace the BCM: Only consider BCM reprogramming or replacement as a last resort, after all other possible causes have been ruled out. This usually requires a specialized scan tool and knowledge of vehicle programming procedures.

Tools Required:

  • Multimeter: Essential for testing voltage, continuity, and resistance.
  • Wiring Diagram: Necessary for identifying the correct wires and terminals to test.
  • Basic Hand Tools: Screwdrivers, pliers, wire strippers, etc., for removing and installing components.
  • Scan Tool (optional): Can be used to read and clear DTCs, and may provide additional diagnostic information.

Related DTCs:

  • B3701 (Intermittent Wiper Delay Input Circuit High): Indicates a voltage signal in the intermittent wiper delay input circuit that is above the expected threshold.
  • B3703 (Wiper Motor Relay Control Circuit Malfunction): Indicates a problem with the circuit that controls the wiper motor relay.
  • Other DTCs related to the BCM or wiper system: These codes may provide additional clues about the underlying problem.

Frequently Asked Questions

  • What does the B3702 code mean? It means the Body Control Module (BCM) is receiving a lower than expected voltage signal from the intermittent wiper delay input circuit.

  • Can I fix this problem myself? Depending on your mechanical and electrical skills, you may be able to diagnose and repair the problem yourself, especially if it involves a simple issue like a corroded connector or a faulty wiper switch. However, if the problem is more complex, such as a BCM malfunction, it is best to seek professional help.

  • Will this code affect my vehicle's performance? The B3702 code primarily affects the operation of the intermittent wipers and will not directly impact engine performance or other critical vehicle systems.

  • How much will it cost to fix this problem? The cost of repair can vary depending on the cause of the problem. A simple fix like replacing a wiper switch may cost around $50-$150, while a more complex repair involving the BCM could cost several hundred dollars.

  • Can I drive my car with this code present? Yes, you can typically drive your car with this code present, but the intermittent wipers may not function properly, which can be a safety hazard in inclement weather.

Conclusion

The B3702 DTC indicates a low voltage condition in the intermittent wiper delay input circuit, typically stemming from a faulty wiper switch, wiring issues, connector problems, or, less commonly, a BCM malfunction. Thorough diagnosis, using a multimeter and wiring diagrams, is essential to pinpoint the root cause and implement the appropriate solution, ensuring the reliable operation of your vehicle's windshield wipers.