C1713

What Does Code C1713 Mean?

The diagnostic trouble code C1713 signifies a detected circuit fault within the Anti-lock Braking System (ABS) specific to the Left Front Wheel Speed Sensor. The ABS control module, which is the primary Electronic Control Unit (ECU) for braking and stability systems, continuously monitors the electrical integrity and signal output of each wheel speed sensor. When the module identifies that the electrical characteristics of the left front sensor’s circuit – such as voltage, resistance, or the frequency/amplitude of the generated signal – deviate from its calibrated parameters, it registers C1713. This deviation could indicate an open circuit (no signal), a short to ground, a short to voltage, or an implausible resistance value. The ABS module interprets this as a failure in the communication path or the sensor itself, disabling critical safety functions that rely on accurate wheel speed data. The primary subsystem affected is the ABS, along with its integrated functionalities like Traction Control System (TCS) and Electronic Stability Control (ESC), which rely entirely on precise wheel speed readings to prevent wheel lock-up during braking, wheel spin during acceleration, and loss of directional control.

Common Symptoms

• ABS Warning Light Illumination: The most immediate and common symptom is the activation of the ABS warning indicator on the instrument cluster.
• Traction Control Warning Light Illumination: Concurrently with the ABS light, the traction control system warning light will typically illuminate, indicating that this system is also disabled.
• Electronic Stability Control (ESC) Warning Light Illumination: The ESC system, being intertwined with ABS and TCS, will also often display a warning light, signifying its operational suspension.
• Disabled Cruise Control: In many vehicles, the cruise control system is disabled as a safety measure when there are active ABS or wheel speed sensor faults.
• Reduced Braking System Performance: While basic hydraulic braking remains functional, the ABS will not intervene during hard braking, potentially leading to wheel lock-up on slippery surfaces.
• Erratic or Inaccurate Speedometer/Odometer Readings: Less common for a single front sensor, but possible in certain vehicle architectures where wheel speed data contributes to vehicle speed calculation.

What Causes the Code C1713?

• Faulty Left Front Wheel Speed Sensor: The sensor itself may have an internal electrical fault, be physically damaged, or suffer from contamination and corrosion leading to signal degradation or failure.
• Damaged Wiring Harness: The wiring connecting the left front wheel speed sensor to the ABS control module can become chafed, cut, corroded, or experience an open circuit or short to ground/voltage due to environmental exposure, rodent damage, or mechanical stress from suspension movement.
• Corroded or Loose Electrical Connectors: The electrical connector at either the sensor end or the ABS module end can develop corrosion, bent pins, or insufficient tension, leading to high resistance or intermittent signal loss.
• Damaged Tone Ring/Exciter Ring: The magnetic or metallic tone ring (also known as the ABS reluctor ring) which the sensor reads, may be cracked, corroded, or missing teeth. This is often part of the wheel bearing, hub assembly, or CV axle.
• Faulty ABS Control Module: Although less common, an internal circuit board failure within the ABS module itself could prevent it from correctly processing the sensor’s signal or supplying proper power/ground to the sensor.

How to Diagnose and Troubleshoot

A systematic approach is crucial for diagnosing C1713:

1. Visual Inspection:
   • Begin with a thorough visual inspection of the Left Front Wheel Speed Sensor and its entire wiring harness. Follow the harness from the sensor, along the suspension components, to where it enters the main vehicle wiring. Look for any signs of physical damage, chafing, cuts, stretched wires, or evidence of rodent activity.
   • Inspect the sensor’s mounting to ensure it is securely fastened and correctly positioned relative to the tone ring. Verify there is no excessive debris or metallic particles adhering to the sensor tip.
   • Examine the Left Front Wheel Bearing/Hub Assembly and the CV axle (if applicable) for damage to the tone ring. Look for cracks, missing teeth, excessive rust build-up, or foreign objects that could interfere with the sensor’s reading.
   • Check the electrical connector at the sensor and any inline connectors for corrosion, bent pins, or signs of improper seating.
2. OBD-II Scanner Data Analysis:
   • Connect a diagnostic scanner capable of accessing the ABS module’s live data.
   • Select “Wheel Speed Sensor” data PIDs and monitor the readings from all four sensors.
   • With the vehicle safely lifted, manually rotate the left front wheel while observing its speed reading. Compare it to the other wheels if rotating them is feasible. A faulty sensor will likely show 0 MPH, an intermittent reading, or a reading that is significantly different and inconsistent compared to the others.
   • Perform a low-speed road test (if safe to do so) while monitoring all four wheel speed sensors. Observe for any dropouts or inconsistent readings from the left front sensor, especially during turns or over bumps.
3. Digital Multimeter (DMM) Testing:
   • Resistance Test (for passive sensors): Disconnect the left front wheel speed sensor. Using a DMM, measure the resistance across the sensor’s two terminals. Compare this reading to the manufacturer’s specification (found in the service manual). An open circuit (infinite resistance) or a short circuit (near zero resistance) indicates an internal sensor fault. (Note: Many modern sensors are active Hall-effect sensors and will not yield a simple resistance reading; this test is mainly for older, passive inductive sensors).
   • Continuity and Short Circuit Test (Harness): With both the sensor and the ABS module disconnected (consult service manual for ABS module connector pinouts), perform continuity checks on each wire of the left front wheel speed sensor harness from the sensor connector to the ABS module connector. Verify minimal resistance (ideally < 1 Ohm). Simultaneously, check for shorts to ground by probing each wire to chassis ground, and for shorts to battery voltage by probing each wire to a known 12V source (ignition off for shorts to power).
   • Power and Ground Supply Test (for active sensors): Reconnect the ABS module but leave the sensor disconnected. With the ignition on, use a DMM to check for reference voltage (typically 5V or 12V) and a good ground at the left front wheel speed sensor connector terminals coming from the ABS module. Absence of proper power or ground indicates a fault in the ABS module’s output or further upstream wiring.

Recommended Repairs and Solutions

Based on diagnostic findings, the following repairs are typically recommended:

• Replace Left Front Wheel Speed Sensor: This is the most common repair. Ensure the new sensor is an OEM equivalent or reputable aftermarket part. Install the sensor correctly, ensuring proper seating and torque specifications are met, and that the wiring is routed away from moving parts and heat sources.
• Repair or Replace Wiring Harness: If the wiring is found to be damaged, perform a professional wire repair. This involves splicing in new wire sections using solder and heat-shrink tubing for durability and weather resistance. For extensive damage, replacement of the relevant section of the harness may be more practical. Always ensure the repair maintains the original wire gauge and shielding (if present).
• Clean or Replace Electrical Connectors: If corrosion or damage is identified at the connectors, clean the pins thoroughly using electrical contact cleaner and a small wire brush or pick. If pins are bent, broken, or severely corroded, the connector body or individual pin may need replacement. Apply a thin layer of dielectric grease to prevent future corrosion upon reassembly.
• Repair or Replace Tone Ring/Wheel Bearing: If the tone ring is confirmed to be damaged, repair involves replacing the component it’s integrated with. This often means replacing the entire wheel bearing assembly or the CV axle, depending on the vehicle design.
• ABS Module Replacement: Only consider replacing the ABS control module as a last resort, after meticulously ruling out all other possibilities (sensor, wiring, tone ring). ABS module replacement often requires specialized programming or coding to the vehicle’s VIN, and a brake fluid bleeding procedure will be necessary afterward.

After any repair, always clear the C1713 diagnostic trouble code using a scanner. Perform a road test to verify that all associated warning lights (ABS, TCS, ESC) remain off and that the ABS system functions correctly, paying close attention to live wheel speed sensor data to confirm accurate readings from the left front sensor across various speeds.