P0711

Code

HUMMER P — Powertrain

TFT Sensor Circuit Range/Performance

Brand: HUMMER

Type: P — Powertrain

Views: UK: 5 EN: 18 RU: 22

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Page language: EN

Causes

Faulty transmission fluid temperature (TFT) sensor (thermistor)
Damaged, corroded, or loose sensor connector or wiring (open, short to ground or power, high resistance)
Poor electrical grounding or reference voltage problem from PCM/TCM
Contaminated or incorrect transmission fluid causing abnormal sensor reading
Internal transmission issue affecting sensor environment (e.g., internal overheating)
Faulty PCM/TCM or intermittent module input fault (less common)

Symptoms

Transmission or check engine light illuminated (MIL/TCM lamp)
Erratic shifting, harsh or delayed shifts
Transmission may enter limp/limitation mode
Incorrect temperature reading in scan tool or vehicle display
Poor shift logic or degraded fuel/shift performance

What to check

Retrieve freeze frame and complete DTC list with a scan tool; note runtime and ambient/engine temps
Monitor TFT PID/parameter with a scan tool during cold start and warm-up; compare to ambient temp and expected warm-up curve
Inspect sensor connector and wiring for corrosion, damage, looseness or oil intrusion
Backprobe sensor and measure signal voltage and ground reference with ignition on and engine running
Measure sensor resistance at the sensor and compare while warming/cooling (or compare to known-good sensor)
Check for continuity to PCM/TCM, and for shorts to battery voltage or chassis ground

Signal parameters

Sensor type: typically NTC thermistor (resistance decreases as temp increases)
Typical behavior: high resistance when cold (several kilo-ohms) down to low hundreds of ohms at normal operating temp (~80°C) — values vary by design
Circuit voltages: reference or pull-up typically in the 0.1–4.9 V range depending on sensor/ECU; expected live-data temperature should rise smoothly during warm-up
Watch for sudden jumps, flatlines, or values stuck at extreme ends (very low or very high voltage)

Diagnostic algorithm

Connect a capable scan tool, read and record freeze frame and all related codes. Note engine/transmission temperature at fault occurrence.
Monitor TFT PID during cold start and warm-up. Confirm whether reading is plausible for ambient/engine temp.
Visual inspection: remove harness connector at sensor, inspect pins for corrosion, oil intrusion, bent pins, or damage.
With ignition off, measure sensor resistance at the connector. Warm/cool the sensor (using ambient change or controlled heat) and verify resistance changes smoothly.
With connector plugged and backprobed, measure sensor signal voltage and reference/ground with ignition on. Compare to OEM spec or expected behavior (smooth change during warm-up).
Perform continuity tests between sensor connector and PCM/TCM to rule out broken wires. Check for shorts to power or ground.
Wiggle-test harness while monitoring live data to reproduce intermittent faults. Repair any damaged wiring or connectors.
If wiring and sensor check out, consider replacing TFT sensor and retest. If problem persists, test or reprogram/replace PCM/TCM per OEM guidance.
After repair, clear codes, perform a drive or warm-up cycle, and re-scan to confirm the code does not return.

Likely causes

Corroded connector or pin at the sensor
Broken or shorted harness on the TFT signal or ground circuit
Failed TFT sensor thermistor
Low or missing reference voltage from control module
Fluid level/condition abnormal (very dirty, burnt or incorrect fluid type)

Fault status

⚠️ Status

TCM/PCM detected a transmission fluid temperature input that is outside the expected range or behaving inconsistently. The module may log the code when the signal is implausible for operating conditions, intermittent, or absent. This can affect shift strategy and may trigger limp mode.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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P0711 — TFT Sensor Circuit Range/Performance