P27E9

Code

Generic P — Powertrain

Transmission Range Control B Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 27 EN: 29 RU: 23

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Page language: EN

Causes

Open or shorted wiring in TR/PRNDL circuit B
Corroded, bent, or pushed-out connector pins at sensor or control module
Failed transmission range sensor / park/neutral position switch (circuit B element)
Poor or missing ground or reference voltage to the sensor
Blown fuse or power supply issue to transmission electronics
Intermittent damage from harness rubbing or water ingress

Symptoms

Check Engine Light or transmission warning lamp illuminated
Transmission stuck in limp/safe mode or limited gear range
Incorrect gear display (PRNDL indicator incorrect)
Vehicle may not crank if system prevents starter engagement from wrong sensed gear (starter interlock)
Transmission may not shift correctly or shifts harshly
No obvious driveability symptoms other than warning lamps on some vehicles

What to check

Read and record freeze frame and live data with a capable scan tool; confirm P27E9 and any related codes
Visually inspect wiring and connectors for damage, corrosion, pushed pins, or moisture at the transmission range sensor and the PCM/TCM connector
Verify fuses and power supplies for transmission control circuits
Backprobe the TR/PRNDL sensor connector and PCM/TCM connector to measure signal, reference and ground voltages with key ON (engine OFF)
Perform a wiggle test of the harness while monitoring the signal to see if the fault is intermittent
Check for continuity to ground from the signal circuit (short to ground) and continuity to the PCM for open circuits

Signal parameters

Reference (supply) voltage to TR sensor typically ~5 V (key ON, engine OFF) — verify per service manual
Circuit B signal low condition: near 0 V (typically
Normal circuit signal range commonly between ~0.5–4.5 V depending on gear position (varies by design)
Signal should change to discrete levels or a variable voltage as shift selector is moved — check live PID while moving selector through positions

Diagnostic algorithm

Retrieve and record DTC(s) and freeze frame with scan tool. Note operating conditions when code set.
Attempt to reproduce fault: cycle ignition and move shifter through every position while monitoring TR circuit B live data.
Perform visual inspection of sensor, harness, and connectors for damage, corrosion, or fluid entry. Repair as needed.
Verify fuses and power sources to transmission control and range sensor circuits.
Backprobe sensor connector: with key ON (engine OFF) measure reference voltage, signal on circuit B and ground. Compare to expected values for the vehicle.
If reference and ground are correct but signal is low, disconnect sensor and inspect pins. Measure resistance of the signal circuit to ground — a short to chassis ground indicates wiring fault.
If the circuit is open when sensor disconnected (no short), connect an isolated bench power or signal to the sensor input per service data and observe PCM response, or swap/replace the TR sensor if available and applicable.
Perform continuity and resistance checks between sensor connector and PCM connector to find opens or shorts. Repair wiring as found (replace sections, repair pins).
After repairs, clear codes and perform a road test while monitoring the TR/PRNDL circuit. Confirm code does not return.
If wiring and sensor check good and symptoms persist, consider PCM/TCM input circuit fault — consult manufacturer's procedures before replacing control module.

Likely causes

Damaged wiring harness (abrasion, chafe, pinched) causing short to ground on circuit B
Corroded or loose connector at the transmission range sensor or control module
Failed/transmission range sensor (circuit B element)
Poor ground or supply/fuse feeding the sensor

Fault status

⚠️ Status

Transmission Range Control circuit B voltage is below the expected threshold (circuit low). The PCM/TCM has detected an abnormally low signal on the TR/PRNDL circuit B input.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours