Code
P1397
BUICK
P — Powertrain
Wheel Speed Sensor 2, G-Sensor Circuit Low Voltage
AI status
Completed
Completed
100%
Causes
- Open or shorted sensor wiring (open to ground or short to ground)
- Corroded, loose or damaged connector at sensor or module
- Failed wheel speed (or G) sensor element
- Damaged wheel bearing or tone ring causing abnormal sensor output
- Faulty ABS/traction control module or internal electronics
- Intermittent wiring harness damage or pinched wires
Symptoms
- ABS and/or traction/stability control warning light illuminated
- Traction control / ABS functions disabled or limited
- Inconsistent or no speed reading from affected wheel on live data
- Possible ABS pump/valve activation faults during braking
- Occasional fault present only under certain conditions (intermittent)
What to check
- Retrieve freeze frame and live data for wheel speed sensors and G-sensor values
- Visually inspect sensor 2, connector and wiring for corrosion, damage or disconnection
- Backprobe connector with key on and engine off to verify reference voltage and ground
- Check sensor resistance and compare to specification (service manual)
- Probe signal while rotating wheel (scope preferred) to confirm waveform or AC voltage
- Wiggle harness and connectors while monitoring live data to reproduce fault
Signal parameters
- Passive (VR) wheel speed sensor: AC sine wave, ~0.1–1.0 VAC at low speed, increasing with wheel speed (specs vary)
- Active/Hall wheel speed sensor: square wave 0–5 V (or 0–12 V on some systems) referenced to module supply; idle position about 2.5 V for some sensors
- G-sensor (accelerometer) typical idle output ~2.5 V (varies by design); small changes with vehicle acceleration/deceleration
- Reference supply: usually 5 V (or vehicle-specific) from ABS module — verify with service manual
Diagnostic algorithm
- Connect scan tool, read code(s) and view live data for all wheel speed sensors and G-sensor while at rest and during drive.
- Identify which physical sensor is ‘Sensor 2’ per vehicle wiring diagram (front/rear, left/right depends on model).
- Visually inspect the sensor, tone ring, mounting, connector and wiring for damage, corrosion, rubbing or contamination.
- With ignition on, backprobe the sensor connector: verify reference voltage, ground continuity and signal circuit voltage. Compare to OEM specs.
- Measure sensor resistance (if passive VR) or output with wheel rotated. Use an oscilloscope for waveform verification if available.
- Perform a wiggle/test drive: manipulate harness and connectors while monitoring live data to isolate intermittent faults.
- If wiring and connectors test good but signal is out of spec, replace the wheel speed/G-sensor and retest.
- If new sensor still shows low voltage, check ABS module supply/ground and repair module connector or consider module replacement after verifying all circuits.
- Clear codes, perform a road test and re-scan to confirm repair.
Likely causes
- Corroded/loose connector at Wheel Speed Sensor 2
- Open/short in sensor signal or ground wire (harness damage)
- Failed wheel speed sensor (internal electronics for active sensors or broken coil for VR)
- Missing or low reference voltage from ABS module
Fault status
Status
Wheel Speed Sensor 2 / G-sensor circuit voltage is lower than expected. The ABS/traction control module detected a low or missing signal on the specified sensor circuit which may disable related stability systems.
Repair difficulty: Medium
Diagnostic time: 1.0 - 2.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email