Code
P1255
LINCOLN
P — Powertrain
Pedal Correlation PDS2 and LPDS Low
Views:
UK: 17
EN: 47
RU: 23
AI status
Completed
Completed
100%
Causes
- Failed pedal position sensor (PDS2 or LPDS)
- Damaged wiring or connector between pedal sensor and PCM (open, short to ground or battery, high resistance)
- Poor or missing 5 V reference or ground to the pedal sensor
- Corrosion, bent pins, or poor connector contact
- Mechanical binding or obstruction in the accelerator pedal assembly
- PCM/internal module fault or software anomaly
Symptoms
- Check Engine MIL on
- Reduced throttle response or limp-home mode (limited power)
- No or inconsistent acceleration when pressing the pedal
- Cruise control disabled
- Inconsistent or jumpy pedal position values in scan tool live data
What to check
- Read DTCs and freeze frame data with a capable scan tool; note stored/active status
- View live data: PDS2 and LPDS voltages/percentages while at rest and while operating the pedal
- Visually inspect pedal assembly, harness, and connectors for damage, corrosion, or contamination
- Backprobe connector and verify 5 V reference and ground presence at sensor connector
- Perform wiggle test on harness and connectors while watching live data for interruptions or changes
- Measure continuity/resistance from sensor pins to PCM; check for shorts to ground or battery
Signal parameters
- Typical pedal sensor signal range: ~0.5–4.5 V (may vary by model); both sensors should move smoothly together
- 5 V reference present at sensor connector (approx. 4.8–5.2 V)
- Sensor ground present (near 0 Ω to chassis/PCM ground)
- Expected difference between PDS2 and LPDS signals: small (typically
- No sudden jumps, drops, or intermittent open readings in live data during pedal travel
Diagnostic algorithm
- Record DTC(s) and freeze-frame data with scan tool. Note when code set and vehicle conditions.
- Inspect pedal assembly and connector for obvious damage, corrosion, water intrusion, or mechanical interference.
- With ignition ON (engine off), backprobe pedal sensor connector(s). Verify 5 V reference and ground are present and stable.
- Monitor live voltages for PDS2 and LPDS while slowly operating the pedal. Confirm both signals increase smoothly and remain correlated.
- If one signal is low or not changing, check continuity between sensor signal pin and PCM; inspect for shorts to ground or battery.
- Wiggle harness and connectors while observing live data to locate intermittent faults. Repair any damaged wiring or poor connectors.
- If wiring and power/ground are good but a sensor output is out of range or remains low, replace the affected pedal position sensor (follow OEM removal/installation procedure).
- Clear codes, perform a functional test and road test. Re-scan for codes and verify normal pedal correlation under all operating conditions.
- If issue persists after sensor and wiring repair, consider PCM/ECM diagnostics or reprogramming per factory procedures.
Likely causes
- Corroded or loose pedal connector pins causing low signal
- Short to ground on one sensor signal circuit causing a low voltage reading
- Failed PDS2 sensor output stage (low voltage)
- Broken or high-resistance ground or 5 V reference feed
- Aftermarket wiring or recent repairs damaged the harness
Fault status
Status
Pedal Correlation PDS2 and LPDS Low — pedal sensor signals low or not correlated.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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