Trouble code: P1705

Daughter's 95 ES300 with less than 60K miles has recently set trouble code P1705. Some web searching indicates code is related to a transmission
direct clutch sensor. The car has no performance related symptoms, e.i. runs fine. After clearing the code, the trouble light stays off until the next restart. Suggested repairs have ranged from replacing the ecm (very expensive) to replacing the direct clutch sensor (lest expensive). Any collective wisdom with this particular code would be appreciated. TIA
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Don,
Don't know if this maps exactly, but I have a 94 es300 and I bought the Lexus manual.. The manual says:
Detection Item "NC2" Revolution sensor circuit malfunction (direct clutch speed sensor)
Diagnostic Trouble Code Detecting Condition Output of direct clutch speed sensor (NC2) is 300 rpm or less under conditions a) and b) (2 trip detection logic) a) Vehicle speed: 32 km/hr (20 mph) or more b) Park/neutral position switch: OFF
-d

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Sounds like a sensor to me. I don't know why they'd be recommending replacing the ECM - this would be like replacing your computer because the keyboard doesn't work.
I'm just reading between lines, but I bet this sensor is used to sense when to lock up the torque convertor. Most modern automatics have a lock-up mode in the torque convertor that directly couples the input and output of the transmission, bypassing the torque convertor hydraulics, when in cruise mode. This gives better mileage. Without the speed sensor working, this lock-up feature is probably disabled. It is not a huge deal, but I'd get it fixed.
- Mark
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Sounds like a sensor to me. I don't know why they'd be recommending replacing the ECM - this would be like replacing your computer because the keyboard doesn't work.
I'm just reading between lines, but I bet this sensor is used to sense when to lock up the torque convertor. Most modern automatics have a lock-up mode in the torque convertor that directly couples the input and output of the transmission, bypassing the torque convertor hydraulics, when in cruise mode. This gives better mileage. Without the speed sensor working, this lock-up feature is probably disabled. It is not a huge deal, but I'd get it fixed.
- Mark
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Thanks to both for reply. She probably wouldn't detect if the convertor was locked or unlocked. Agree she should get it fixed.
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