vanguy

Hi, this code just came up on our 99 AWD. The car seems to be running fine but does anybody know what this code means? I hope it is not expensive to fix. Thanks.

carguy07

Looks like the Input Turbine Speed Sensor. I don't know anything about it though. I will have to see what my manuals say about it.

See post #3

https://www.clublexus.com/forums/rx-...ed-sensor.html

mikey00

This code has only come up once on the forum in the past that I can find. It indicates a Input Turbine Speed Sensor failure. Are you sure you are shifting into overdrive? I thought this was one of the codes that would prevent your trans from shifting into OD, but I could be wrong.
I would first disconnect the battery for a few minutes. This will reset the code and also reset what your ECM has learned abiut your driving habits. If your lucky, this may fix the problem. If not, here's what the Lexus service manual says about it:
DTC P1725: INPUT TURBINE SPEED SENSOR
NOTE: Sensor may also be referred to as NT revolution sensor.
Circuit Description
Input turbine speed sensor detects rotation speed of input
shaft. By comparing input turbine speed sensor signal and counter gear
speed sensor signal, ECM detects shift timing of gears and controls
engine torque and hydraulic pressure in response to various conditions
to ensure smooth transaxle shifting. DTC will set if ECM detects
vehicle speed of 20 MPH or more, transaxle is in 2nd, 3rd or OD gear,
shift solenoids and PNP switch status is normal, and input shaft speed
is less than 300 RPM. Possible causes are:
* Open or short in speed sensor circuit.
* Speed sensor malfunction.
* ECM malfunction.
Diagnosis & Repair Procedure
1) Access ECM, located behind glove compartment. Disconnect
appropriate ECM connector. Using a DVOM, check resistance between ECM
connector terminals NT+ and NT-. See Figs. 9 and 10. Resistance should
be 560-680 ohms. If resistance is as specified, replace ECM. If
resistance is not as specified, go to next step.
2) Remove input turbine speed sensor from transaxle. See
Fig. 1. Check resistance between speed sensor terminals. Resistance
should be 560-680 ohms. Connect a DVOM to speed sensor terminals.
3) Measure voltage when a magnet is put close to tip of speed
sensor, then taken away quickly. See Fig. 8. Voltage generated should
be intermittent and extremely low. If resistance and voltage are not
as specified, replace speed sensor. If resistance and voltage are as
specified, check and repair wiring harness or connector between speed
sensor and ECM.

mikey00

If the battery disconnect thing doesn't fix the problem you may want to try cleaning and swapping the sensors. There are 2 identical sensors in the transmission, the Counter Gear Speed Sensor and the Input Turbine Speed Sensor. These are easy to get at and remove, clean and swap. The hardest part is removing the air filter box. The Input Turbine Speed Sensor sits horizontally directly below the air box. The Counter Gear Speed Sensor sits at a 45 degree angle facing the battery. The sensors will have some metallic fuzz on their magnetic tip which may be causing your problem. Here is a post I did a while back explaining how to remove them:
https://www.clublexus.com/forums/rx-...nsmission.html

vanguy

Can you provide the link to your post as to where and how to remove the sensor? Thanks.

carguy07

https://www.clublexus.com/forums/rx-...nsor-help.html


https://www.clublexus.com/forums/rx-...nsmission.html

vanguy

Just an update. I took the car into a local mechanic and did confirm it was the transmission senor but not the Input Turbine speed sensor. It is the one that is not under the airbox. He told me the sensor seems to be working intermittenly hence I got the CEL on and off. Anyways, he replaced it and hope that's that. The car had no symtoms when the CEL was on.