I took my SC400 into the Lexus Dealer. I checked my default codes before taking the car in. I got #54 under the ABS system and #43 under the TRAC system. Lexus found #54 in ABS and #45 in TRAC.
#54 in ABS. Tech replaced the pressure hose and the TRAC Accumulator.
#45 in TRAC is due to Short in Main TPS.
The new TPS has raised the idle [in Park] to 900-1000 rpm and acceleration is abrupt instead of smooth off idle. I suppose I cannot adjust the TPS without special equipment. I have the old TPS and am considering reinstalling it and recheck for codes.
TPS part #8945222090
hose #9094706006, o-rings[4] #9030113011
accumulator #4797024011

I did get a 15% discount on parts. A little bit helps. I wonder if this new TPS will wreck my gas mileage? I was getting 31 mpg on the highway.

 

Pictures on the pressure hose and the TRAC Accumulator please. Yes, you can adjust the TPS. Your car should idle at around 649 rpm. There are two TPS if you have Traction Control system. One if you dont have it TCS. There are two screws on the TPS. Loosen it little and counter rotate the TPS. You should noticed the rpm goes down. Here is a picture of TPS if you dont know where it is. Its infront of the throttle body.

 

Actually idle is 600. Cold idle is 1200RPM.

 

Thanks Lextreme. I did the counter rotation of the TPS and the idle did drop down. I also disconnected the battery to erase any settings, too.
A LS400 with twin turbos? What rearend did you install? You certainly need a good Posi unit for that much horsepower.
The Accumulator is over by the Brake Booster and the pressure hose connects the Accumluator to the TRAC pump. It was weeping a bit of fluid. The accumulator costs $544 while the pump lists for $1808. I was prepared to pay for a pump; I guess I lucked out this time.