P1391

Code

CHRYSLER P — Powertrain

Wheel Speed Sensor 1, G-Sensor Circuit Performance

Brand: CHRYSLER

Type: P — Powertrain

Views: UK: 19 EN: 32 RU: 24

AI status

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Page language: EN

Causes

Damaged or contaminated wheel speed sensor (sensor 1)
Damaged, corroded or loose connector at the sensor or ABS module
Broken, shorted or chafed wiring between sensor and control module
Missing, damaged or contaminated tone/reluctor ring (missing teeth, heavy corrosion)
Failed wheel bearing or hub causing sensor misalignment
Poor ground or reference voltage to the sensor

Symptoms

ABS warning lamp illuminated (may be steady or flashing)
Traction control/ESP/stability lamp illuminated or disabled
Park/shift or speed-dependent features may be inactive or behave erratically
Inconsistent or zero wheel speed reading for one wheel in live data
Possible speedometer or cruise control faults (if vehicle uses same speed source)
Intermittent faults that appear with certain wheel movement or temperature

What to check

Connect a scan tool that supports Chrysler ABS/traction systems and read stored codes and freeze frame data
Clear codes and test-drive to reproduce; monitor live wheel speed and G‑sensor channels
Visually inspect sensor 1, connector, and wiring for corrosion, damage, pin push-out, or water intrusion
Inspect the tone/reluctor ring for missing teeth, heavy corrosion, or accumulated debris
Backprobe the sensor connector and verify reference voltage and ground (if Hall-type) with key ON
Measure sensor resistance with a multimeter (compare to shop data) and check for open/short to ground/rail

Signal parameters

Hall-effect speed sensor: typically a 5 V reference and pulsed signal output between ~0–5 V (square wave) synchronized to tone ring teeth
Variable‑reluctance (VR) sensor: AC sine-like voltage whose amplitude increases with wheel speed (tens of mV at low speed to several volts at higher speed)
G‑sensor (accelerometer): typically provides a DC voltage centered near mid‑supply (around ~2.5 V on 5 V systems) that moves above/below center with acceleration; exact values vary by sensor and manufacturer
Expected: stationary = no wheel pulses; smooth, regular pulses at increasing frequency as wheel speed increases

Diagnostic algorithm

Capture DTCs and freeze frame with a OEM-capable scan tool; note whether the fault is permanent or intermittent.
Visually inspect sensor 1, connector, wiring harness routing, and tone ring for damage, corrosion or debris. Repair obvious problems.
With ignition ON (engine off), backprobe sensor harness: verify reference voltage (if Hall), signal circuit continuity, and ground. Compare to manufacturer specs.
Measure sensor resistance (if applicable). An open or shorted reading indicates a failed sensor; replace sensor if out of spec.
Spin the wheel while monitoring live wheel speed data or use an oscilloscope to verify signal waveform and amplitude. Check for missing pulses or noisy/irregular waveform.
Wiggle test wiring and connector while watching live data to locate intermittent faults caused by movement.
Inspect tone ring for damaged or missing teeth or heavy corrosion; clean or replace if required. Check bearing/hub runout and replace worn bearings that misalign the sensor gap.
If wiring and sensor test good, verify continuity and resistance between sensor connector and ABS/traction control module pins and inspect module connector pins for corrosion/push-out.
If all external checks are good and wiring is intact, consider module diagnostics or replacement per OEM procedures (module reprogramming or bench testing may be required).
After repairs, clear codes and road test while monitoring live data to confirm correct, stable wheel speed and G‑sensor readings.

Likely causes

Corroded/loose sensor connector or pin (common on older vehicles)
Damaged reluctor/tone ring (rust, chipped, missing teeth) causing inconsistent pulses
Broken or chafed wiring harness near the wheel or suspension (pinched or rubbed through)
Failed wheel speed sensor element (open or shorted)

Fault status

⚠️ Status

Controller detected implausible or poor performance in Wheel Speed Sensor 1 / G‑Sensor circuit. Module flagged inconsistent, missing, or out‑of‑range signal from that circuit and stored DTC P1391.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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