Code
P1771
DAEWOO
P — Powertrain
Gearshift pos. sensor mal
Views:
UK: 14
EN: 32
RU: 22
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring between sensor and transmission/TCM
- Poor or corroded connector or pin contact at sensor or TCM
- Failed gearshift position sensor (transmission range sensor / PRNDL)
- Physical damage, water ingress or contamination of the sensor
- Mechanical misalignment or binding of the shift linkage/cable
- Intermittent fault due to vibration or broken wires
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
- Incorrect or flashing PRNDL/gear indicator on dash
- Vehicle may not start or starter disabled when transmission not seen in Park/Neutral
- Transmission stuck in one gear or enters limp/limited mode
- Unexpected shifting behavior or inability to select gears
- Intermittent loss of gear signal (symptoms come and go)
What to check
- Retrieve freeze frame and live data with an OBD-II scan tool and confirm P1771 is present
- Visually inspect wiring and connectors at the gearshift position sensor and TCM for corrosion, damage, or looseness
- Check for related codes (PRNDL/TRS or general transmission codes)
- Verify battery voltage is stable during testing (low voltage can create false codes)
- Inspect shift linkage/cable and selector for proper movement and adjustment
Signal parameters
- Reference voltage to sensor typically 5.0 V (key ON) — confirm presence at connector
- Sensor output voltage varies with gear position (typical range ~0.5–4.5 V depending on design) — distinct voltage levels for P, R, N, D
- Continuity: sensor signal circuit should not be open; expected continuity to TCM pin (low ohms)
- No short to battery voltage or ground on signal circuit (
- When shifting through positions, signal should change and remain steady in each position
Diagnostic algorithm
- Connect scan tool, read and record DTCs and live data for gear position/PRNDL values
- Verify battery voltage is within specification (12.4–12.8 V with key off, >12 V with key on)
- Perform a visual inspection of sensor, connector and harness; repair obvious damage and reseat connectors
- With connector disconnected, check for proper reference voltage and ground at the sensor harness (key ON, engine OFF). If missing, trace supply/ground to TCM
- Backprobe the sensor signal pin and observe voltage while moving shift lever through all positions — confirm distinct stable voltages for each position. Note any intermittent or no-signal conditions
- If voltage levels are correct at harness but not at TCM, check continuity between sensor connector and TCM pin for open or high resistance (repair wiring as needed)
- If wiring and connectors are good but signal is incorrect or does not change correctly with shift lever, replace the gearshift position sensor
- After repairs, clear codes, perform key cycles and a test drive; verify code does not return and gear indicator/operation is normal
- If problem persists after sensor and wiring verified, inspect shift linkage adjustment and TCM input circuits; consider TCM fault after eliminating wiring and sensor issues
Likely causes
- Corroded/loose connector at the gearshift position sensor
- Broken or pinched wiring in the harness between sensor and TCM
- Failed sensor element (internal wear or water damage)
- Shift cable out of adjustment or jammed linkage
Fault status
Status
P1771 — Gearshift position sensor circuit malfunction: invalid or missing gear position signal to transmission control.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
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