Transmission Fluid Temperature Sensor A Circuit High Input
The transmission fluid temperature sensor is reporting a voltage signal that is higher than the PCM expects, indicating either a sensor fault or wiring issue. This prevents accurate transmission temperature monitoring and can cause improper transmission shift timing and torque converter operation.
What You Might Notice
- Check engine light illuminated
- Harsh or delayed gear shifts
- Improper torque converter clutch operation
- Transmission overheating
- Reduced fuel economy
Most Common Causes
- 1
Faulty transmission fluid temperature sensor
The sensor itself has failed or drifted out of calibration, causing it to send an artificially high voltage signal to the PCM.
- 2
Wiring or connector issues
Corroded, loose, or damaged wiring connections between the sensor and PCM can cause high voltage readings or intermittent signal problems.
- 3
PCM or transmission control module fault
A malfunctioning engine or transmission control module may misinterpret the sensor signal or have an internal voltage reference problem.
- 4
Transmission problems
Internal transmission issues can affect sensor operation or cause the transmission to run hotter than normal, triggering the high input code.
How to Diagnose It
- 1
Check Faulty transmission fluid temperature sensor — The sensor itself has failed or drifted out of calibration, causing it to send an artificially high voltage signal to the PCM.
- 2
Check Wiring or connector issues — Corroded, loose, or damaged wiring connections between the sensor and PCM can cause high voltage readings or intermittent signal problems.
- 3
Check PCM or transmission control module fault — A malfunctioning engine or transmission control module may misinterpret the sensor signal or have an internal voltage reference problem.
- 4
Check Transmission problems — Internal transmission issues can affect sensor operation or cause the transmission to run hotter than normal, triggering the high input code.
How to Fix It
- 1
Replace transmission fluid temperature sensor
Remove the faulty sensor from the transmission pan or case and install a new OEM or quality replacement sensor, then clear the code and test drive to verify.
- 2
Inspect and repair wiring and connectors
Check the sensor wiring harness for corrosion, damage, or loose connections. Clean corroded terminals with electrical contact cleaner and reseat connectors firmly.
- 3
Test PCM/transmission control module
Use a diagnostic scanner to verify sensor voltage readings match actual transmission temperature. If readings are still incorrect, the PCM or transmission control module may require replacement.
- 4
Check transmission fluid condition
Examine transmission fluid color and smell for signs of overheating or internal damage. If fluid is dark, burnt, or foamy, perform a transmission fluid and filter change.
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