🚨 Diagnostic Profile
- Vehicle/Equipment Make: GENERIC
- Technical Description: Left Rear Wheel Speed Sensor B Circuit High
This code is a Chassis (C) code, meaning it is monitored and stored by the Electronic Brake Control Module (EBCM) or the ABS/Stability Control Module. A ‘Circuit High’ condition for the Left Rear Wheel Speed Sensor (WSS) indicates that the control module is detecting a voltage signal from the sensor circuit that is higher than the expected calibrated range. This typically points to a short circuit to a power source (such as a chafed wire touching a 12V reference wire), an open circuit causing voltage to default high, or a failing internal sensor element. When this fault is active, the ABS module cannot accurately calculate the rotational speed of the left rear wheel, which compromises the Anti-lock Braking System, Traction Control, and Electronic Stability Control functions, often resulting in these systems being disabled until the fault is cleared.
🚨 Repair Difficulty Tier
- Difficulty Rating: Intermediate
This repair requires the use of a digital multimeter to check for proper resistance and voltage within the wiring harness, as well as a scan tool capable of reading ABS module data and live wheel speed sensor PID values. While replacing the sensor itself is often straightforward, diagnosing a wiring short versus a sensor failure requires careful electrical testing skills.
🛠️ Resolution Steps
- Step 1: Preliminary Inspection
Begin with a visual inspection of the left rear wheel speed sensor and its connector. Check for corrosion, bent pins, or damage to the sensor tip. Follow the wiring harness from the sensor toward the vehicle’s main harness, looking for chafed insulation, pinch points near the suspension travel, or evidence of rodent damage that could cause a short to a voltage source. - Step 2: Diagnostic Verification
Using a scan tool, access the ABS module and view live wheel speed sensor data for all four corners while slowly rolling the vehicle or performing a wheel spin test (with the vehicle safely lifted). Compare the Left Rear sensor’s voltage/frequency output to the other wheels. Disconnect the sensor and use a multimeter to check for continuity to ground or unintended voltage on the signal wires with the key on; a reading of battery voltage on the signal circuit confirms a short to power. - Step 3: Resolution & Reset Process
If a wiring short is found, repair the damaged section using proper automotive-grade splicing and heat-shrink tubing, ensuring the repair is isolated from moving suspension components. If the sensor itself tests faulty or shows no change in resistance when wheel position is altered, replace the Left Rear Wheel Speed Sensor. After repair, clear the stored code using the scan tool and perform a test drive to confirm the ABS/Traction Control warning lights remain off and wheel speed data reads consistently across all sensors.
📦 Parts, Labor, and Budget Estimates
- Required Components/Software: Left Rear Wheel Speed Sensor, Wiring Harness Repair Kit (if applicable), Digital Multimeter, OBD-II/Enhanced Chassis Scan Tool
- Average Component Price: $35 – $150 USD
- Estimated Labor Hours: 0.5 – 1.5 hours
- Total Estimated Budget: $90 – $280 USD