YODAONE

1998-2000 LS400 A650-E transmission integrates a fluid temperature sensor (thermister) within solenoid array wiring harness.(not a separate service item)

Our transmissions shift at higher rpm until a certain operating temperature is reached...probably on account of this sensor directed the ECU.

This harness has spent 20 years drenched in transmission fluid, so no doubt the thermister and sealing o-ring are tired...

$50 for 82125-30460 harness assembly from Lexus.

Transmission solenoid array wiring harness. The probe (blue casing) in upper right is thermister.
P.N. 82125-30460
Toyota used gold-plated contacts (bottom two) for the thermister sensor (verified with multimter)



Transmission Temperature Sensor is contained in blue housing.

Stroock639

how easy is changing it? thanks for the info

YODAONE

I removed transmission crossmember (you must support transmission to avoid wrenching driveshaft, center bearing, tailshaft bearing, Guibos, etc)

The time consuming part is dropping the transmission pan....close quarters to work and you have to separate the pan from transmission housing. A special service tool to cut through old FIPG is worth it. Use OEM FIPG and be sure mating surfaces are absolutely clean and dry (on transmission side this is sometimes difficult due to dripping fluid..especially if using wheel.ramps)

Different length pan bolts are used so use a piece of cardboard or foam as template to maintain bolt orientation.

After disconnecting the external transmission connector (understand how it separates) and internal solenoid connectors (study new harness to understand orientation of connector lances), the harness removes via the transmission body through hole.

The new harness is installed in reverse order.....feed the longest wire through first..followed by next longest, etc.

Take pictures of orientation of wiring clamps, etc.

If you have someone competent willing to do for $100, then something to consider...as long as they use Toyota FIPG

About 3-4 quarts of type IV transmission fluid.

Consider replacing transmission screen (not because the screen requires replacement , but because the three cork seals are tired...and less expensive to replace as an assembly)

Acquire new transmission drainplug bolt and crush washer.. Mind the torque on all fasteners..

Stroock639

great thanks so much

JetCat

YODAONE ... very interesting post .... I am curious ... since changing out this part, have you noticed any difference in shift quality?