Code
C1705
Other
C — Chassis
Left Rear Center Sensor Circuit Short to Vbat
Views:
UK: 25
EN: 64
RU: 48
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring contacting battery voltage feed
- Corroded/contaminated or pushed-back connector pin contacting Vb
- Failed wheel speed sensor with internal short to supply
- Short on harness to an accessory or fused ignition/battery feed
- Faulty ABS/traction control module input (less common)
- Water ingress or foreign debris causing shorting at connector
Symptoms
- ABS/ESC warning lamp illuminated
- Traction control or stability control disabled
- Possible speedometer/odometer irregularities if system uses same sensor data
- Loss of ABS/traction functions for affected wheel
- Stored DTC C1705 (or similar) in ABS/traction module
What to check
- Scan tool: read DTC, freeze frame and live data for all wheel speed sensors
- Compare left rear center sensor data to other wheel sensors (should show pulses/changes with wheel movement)
- Visually inspect harness and connector at left rear center sensor for damage, corrosion, water, pin push-out or bent pins
- Backprobe connector with ignition ON and with wheel rotated (or vehicle lifted) to observe signal with a scope or multimeter
- With connector unplugged, check harness pin for battery voltage (should not be Vb on signal pin)
- Wiggle harness while watching live data to reproduce fault
Signal parameters
- Expected: wheel speed sensors typically provide a pulsed AC (passive) or a digital/pulse signal from ~0–5V (active Hall/VR types supply dependent). Reference/supply to sensor often 5V or switched 12V depending on design.
- Fault with short to Vb: signal line measures near battery voltage (~12–14V) or shows a constant high level rather than pulses when wheel rotates.
- Open/grounded conditions: open = no signal; short-to-ground = ~0V; short-to-Vb = ~battery voltage — check against other wheel sensor readings for comparison.
Diagnostic algorithm
- Retrieve freeze frame and live data with a scan tool. Confirm C1705 and check whether fault is current or intermittent.
- Visually inspect the left rear center sensor, connector, and harness routing from wheel to chassis for damage, corrosion, or signs of rubbing. Repair visible damage.
- With ignition ON (engine off for safety), backprobe the sensor connector: identify power/reference, ground and signal pins from factory wiring diagram.
- Measure at the harness (connector still plugged in) the signal pin voltage while slowly rotating the wheel or driving wheel by hand. Expected: pulsed or varying waveform. If signal reads ~battery voltage (constant high), suspect short to Vb.
- Unplug the sensor connector. Measure voltage on the harness signal pin to body/chassis ground. If it is at battery voltage with sensor disconnected, the short is in the harness or module side. If it is not at battery voltage, reconnect and measure at sensor side to isolate sensor vs harness.
- Check sensor electrical characteristics: for passive sensors measure AC voltage while spinning wheel; for active/Hall type measure sensor resistance and supply voltage per spec. Replace sensor if out of spec or internally shorted.
- Perform continuity and short checks between the signal wire and battery positive, ground and chassis using an ohmmeter with battery isolated if required by procedure. Repair or replace damaged wiring, connector or splice.
- If harness and sensor check OK, inspect ABS/traction control module connector and pin condition. If wiring into module shows no faults but short persists, consider module input fault and refer to module repair/replacement procedures.
- Clear codes and road test to confirm repair. Verify no return of C1705 and normal wheel speed readings.
- Note: follow vehicle manufacturer wiring diagrams and safety procedures (support vehicle, chock wheels, disconnect battery where required by manufacturer procedures). Do not replace parts without confirming cause.
Likely causes
- Chafed harness where it rubs on chassis or suspension components causing B+ contact
- Connector pin bent so it contacts adjacent battery feed pin or terminal
- Sensor internal short due to moisture or internal electronics failure
- Incorrect previous repair routing or splice tied into constant battery feed
- Shorted module input caused by internal failure
Fault status
Status
Left Rear Center sensor signal circuit shorted to battery voltage (Vb) detected by ABS/traction control module; sensor input reads high/constant voltage instead of pulsed wheel speed signal.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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