Turbine Speed Sensor Circuit
This code indicates a problem with the turbine speed sensor circuit.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The turbine speed sensor measures how fast the turbine in the transmission is spinning. A faulty sensor or wiring issue can cause the computer to think the speed is wrong, which messes with shifting and engine performance.
What the computer is actually seeing
The ECM monitors the turbine speed through the sensor, expecting a steady voltage signal that reflects the actual turbine speed. If the voltage is outside of a specified range or if there's no signal, it sets SPN 3705.
What a healthy reading looks like
The turbine speed sensor should output a voltage between 0.5V and 4.5V as the turbine speed varies.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the fluid level in the transmission. It should be at the manufacturer's specified level.
- 22. Inspect the wiring and connectors for damage or corrosion at the turbine speed sensor.
- 33. Measure the voltage at the sensor connector while the engine is running. It should be between 0.5V and 4.5V.
- 44. If there's no voltage or it's out of range, replace the turbine speed sensor and retest.
- 55. If voltage is good, check the TCM for faults or update to the latest software.
Common causes
- Faulty turbine speed sensor
- Damaged wiring or connectors
- Faulty transmission control module (TCM)
- Fluid contamination in the transmission
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive for long distances, as improper shifting can occur.
Will this code come back after clearing it?
If the underlying issue isn't fixed, yes, it will likely return.
Why does this code pair with other codes?
SPN 3705 can be related to shifting issues, which may trigger codes for related sensors.
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