I own a 2002 Lexus GS300 and I just love this car as it runs well, all electronic components working fine...or so I thought. One morning, the battery went dead. Recharged it and charge was restored after a few hours. Run the engine but the engine RPM just was sitting at idle; only when you depress the acc pedal to the floor would RPM rev up. DTCs indicated the following code : PO120/P1126/P1128. Did all test including scope and resistance and all TPS, APPS and throttle motor control was good. The following day I decided to do some basics - remove inrake resonator and started cleaning the throttle body. After a few minutes, the engine was back to normal !!!
A simple THROTTLE BODY CLEANING every so often comes a long way.!!!
My thingking of why the battery went dead is this : the throttle plates must have been slightly open, locking the clutch inside the throttle control motor that was trying to adjust the plates continously. This was evident of a "faint" whirring sound in the throttle motor assembly when I was inspecting the engine area.
Electronics and flat batteries don't play well together. The question is cause and effect or effect and cause, I would want to be 100% sure it wasn't a battery with a dead cell or parrasitic drain.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Most likely the throttle body did not kill your battery.
The throttle bodies on Toyota's almost always have to be cleaned if the battery dies or is replaced without a memory saver. If the throttle body is very dirty, I have seen them set false DTC's and sometimes stall the engine. Enjoy that Lexus, they are great cars.
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