Code
P27F2
Generic
P — Powertrain
Transmission Range Control B Position Sensor/Switch Circuit High
Views:
UK: 15
EN: 37
RU: 20
AI status
Completed
Completed
100%
Causes
- Open or short to battery voltage on the TR sensor B signal wire
- Faulty transmission range control sensor / park-neutral switch (B)
- Corroded, bent, or disconnected connector/pins at sensor or PCM
- Damaged or chafed wiring harness (short to battery/other circuits)
- Poor or lost ground or reference voltage to the sensor
- Faulty PCM / transmission control module internal driver
Symptoms
- Malfunction Indicator Lamp (MIL) or transmission warning light ON
- Incorrect gear indicator or gear selection mismatch
- Transmission may go into limp/limitation mode or refuse to shift
- Vehicle may not crank/ start if PCM cannot detect Park/Neutral
- Interrupted cruise control or related drivability functions
What to check
- Retrieve freeze frame and live data with a scan tool; confirm DTC and whether it is current or historic
- Visually inspect sensor connector and wiring for damage, corrosion, or bent pins
- Check for proper reference voltage (usually ~5 V) and good ground at the sensor connector
- Backprobe signal wire with a DVOM or scope to observe voltage with gear changes
- Perform wiggle test on harness and connector while monitoring signal for intermittent changes
- Measure continuity and resistance from sensor connector to PCM pin to detect opens/shorts
Signal parameters
- Reference voltage typically ≈ 5 V (check manufacturer spec)
- Signal output typically varies within ≈ 0.5–4.5 V across gear positions (manufacturer-specific)
- High/open condition: signal voltage above expected range (e.g., >4.8 V) or floating
- Low/short condition: signal voltage near 0 V (not this code but useful for comparison)
- Expected continuity from sensor signal pin to PCM pin: near 0 ohms; infinite = open
- Typical sensor resistance (when applicable): manufacturer-specific — often a few hundred ohms to several kiloohms
Diagnostic algorithm
- Read and record all stored DTCs and freeze frame data with a scan tool. Note conditions when the code set.
- Visually inspect the TR sensor B connector and harness for damage, corrosion, water, or detached pins. Repair any obvious damage.
- With ignition ON (engine off) backprobe the sensor connector: verify reference voltage and ground terminal for proper values per manufacturer spec.
- Backprobe the signal terminal and observe voltage with the transmission shifted through positions (or as commanded via scan tool). Compare to expected range: an abnormally high or floating voltage confirms the DTC symptom.
- If signal is high or floating, disconnect the sensor and measure voltage at the harness connector. If voltage remains high with sensor disconnected, suspect wiring short to battery or backfeed. If voltage drops to expected, suspect the sensor.
- Check continuity/resistance between the sensor signal terminal and the PCM/transmission control module pin. Repair open circuits or high resistance.
Likely causes
- Break in signal wire or connector corrosion causing high/float voltage
- Sensor internal failure (open or stuck high output)
- Terminal pushed out or bent causing backfeed from fused circuit
- Aftermarket modification or repair caused wrong routing or pinout
- PCM/transmission control module fault (less common)
Fault status
Status
Transmission Range Control B Position Sensor/Switch Circuit High — electrical fault on the TR sensor 'B' circuit (open/short/high voltage).
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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