Input/Turbine Speed Sensor "B" Circuit No Signal
The PCM detected no voltage signal from the input/turbine speed sensor B circuit, which monitors transmission fluid flow and gear ratio. This sensor is critical for transmission shift timing and electronic speedometer operation.
What You Might Notice
- Erratic or inoperative speedometer reading
- Transmission fails to shift or shifts harshly
- Odometer not functioning
- Check Engine light illuminated
- Transmission stuck in one gear or limp mode
Most Common Causes
- 1
Open or broken wiring harness
The wiring between the sensor and PCM is disconnected, broken, or corroded. This is the most common cause of complete signal loss.
- 2
Faulty input/turbine speed sensor B
The 3-wire electromagnetic sensor has failed internally or lost its magnetic field strength, preventing voltage generation.
- 3
Loose or corroded connector
The sensor connector is loose, unplugged, or corroded, breaking the electrical circuit and preventing signal transmission.
- 4
PCM circuit failure
The powertrain control module input circuit for sensor B is damaged or malfunctioning, unable to receive the signal.
How to Diagnose It
- 1
Check Open or broken wiring harness — The wiring between the sensor and PCM is disconnected, broken, or corroded. This is the most common cause of complete signal loss.
- 2
Check Faulty input/turbine speed sensor B — The 3-wire electromagnetic sensor has failed internally or lost its magnetic field strength, preventing voltage generation.
- 3
Check Loose or corroded connector — The sensor connector is loose, unplugged, or corroded, breaking the electrical circuit and preventing signal transmission.
- 4
Check PCM circuit failure — The powertrain control module input circuit for sensor B is damaged or malfunctioning, unable to receive the signal.
How to Fix It
- 1
Inspect and repair wiring harness
Visually inspect the wiring from the input/turbine speed sensor B to the PCM for breaks, corrosion, or loose connections. Repair or replace damaged wiring and ensure all connectors are fully seated.
- 2
Clean and reseat connector
Disconnect the sensor connector, clean both male and female terminals with electrical contact cleaner to remove corrosion, and firmly reconnect. Test for voltage signal.
- 3
Replace input/turbine speed sensor B
Remove the faulty sensor from the transmission housing and install a new 3-wire electromagnetic input/turbine speed sensor. Verify proper installation depth and secure wiring.
- 4
Test PCM and seek professional diagnosis
If wiring and sensor replacement do not resolve the issue, the PCM input circuit may be damaged. Have a technician perform PCM circuit diagnostics or consider PCM replacement.
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