Help needed with diagnosing my lexus

Hello all. I've been a scannerdanner watcher for a long time and have been wrenching on cars for a number of years. I finally need some help on my personal car so I'm reaching out.

I have a 2004 Lexus ES330. The wife borrowed it and closed the seatbelt in the door. This didn't allow the door pin switch to trigger the lights to turn off, killing the battery. They tried to jump start it and it wouldn't start.
I suspect they hooked the jumper cables up backwards because when I arrived, the car would only light up the check engine light and had a few blown fuses. One being a 120 amp alternator fuse, and 2 or 3 other fuses (radio and whatnot)
So I checked every fuse with my multimeter and swapped the bad for good fuses. I visually checked the other larger fuses that are see through and all the other ones look good. The battery was dead so I jump started it and finally got it to run. Checked charging voltage was around 14v, got into it to drive away and no signal from the Accelerator pedal. The check engine light was on along with The VSC and TRAC?(I think) light were on. The only thing I could get from the Accelerator pedal was on first start up, mashing the throttle would change the abnormally high 900 rpm idle up to 1000 RPMS and when I let off the throttle, the engine would bog down to 300 RPMS and settle back to its high idle. That's it. Having few tools at my disposal, I packed up and went and grabbed my Snap on Verus.
Codes thrown

P0121 Throttle/pedal sensor switch "A" circuit range/performance
P0123 Throttle/pedal position sensor switch "A'' circuit high
P0504 Brake switch A/B correlation
P2118 Throttle actuator current range performance
P2135 Throttle/pedal position sensor/switch a/b correlation

I checked the accelerator pedal sensors on the scanner and both sensors seemed to read in tandem from idle up to WOT. Like 1 to 4 volts if I remember correctly with one sensor being about a volt less than the other throughout its range of motion.

Throttle was stuck at 18% and only unplugging it made it's % change up to 100%. No reaction to accelerator input.
So now that I have 4 days off I need to figure out what's wrong with my daily driver. I suspect either 1 of 4 things.
1. bad accelerator pedal switch
2. Bad throttle body motor/switch
3. Bad engine computer
4. Wiring issue between the computer and throttle body

Someone please help me out here. I think my next move is to use my scope(for the first time. Yikes!) To look at the pedal sensors to see if the voltage drops out and my multimeter was too slow to catch it. I'm going to check for voltage at the throttle body as well.
Any help would be much appreciated
Vinny

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The best thing you can do is record the fault codes as you have done, then clear them and start from scratch. Some faults codes could be from months or even years ago and were just never cleared.
Also sometimes leaving a car idling for a while allows it to relearn its idle values if it has lost its memory in a reverse jump start. Leave it idling for 5 minutes, then add some loads like headlights and blower motor, if it's auto then put it into gear and learn its idle under that load as well. Go through this procedure then try to rev it and re-check fault codes.

Totally agree with Desmond. Clear codes and see who comes back. Given that the battery was jumped backwards AND dead, I'd consider doing a hard reset. Disconnect the battery cables, tie them together with a jumper, and have a cup of coffee. Come back and start over.

Before going much further, are you sure you found all the popped fuses? I really don't mean to insult, just been here before. :lol: The ETCS fuse, 10A in the underhood fuse box is what we're really interested in, given the codes. That's the power feed to the PCM for the throttle motor, and it always blows when the battery gets connected backwards.

So a little update...
I have now gotten her up and running . Something I have never seen before. The ECTS fuse passed a continuity test with both my multimeter and a fuse checker, but had been blown 99.9% . I pulled it for a visual inspection and it appears to be blown with a very tiny part still intact in the middle. I presume it just couldnt support any type of load. I'll try to post up a picture.
I checked everything out and the alternator had quit charging at some point. Plug at the alternator was getting a signal and wasnt putting anything out, so I went and
Swapped it out at AutoZone (previous owner had a lifetime warranty one in there so why not) and it charges now. Fuel trims looked great. Then it threw p2238 p2241 for the A/F Ratio Sensors Pumping Current Circuit Low. Cleared them and one code(b2s1) came back. I pulled up the voltages and % on my Verus and the B2S1 sensor was flat-lined. I did a few restarts and nothing helped. I pulled the A/F relay and swapped it with the DRL relay and cleared codes and started it. Now the A/F sensors are reading correctly and responding to throttle input. No DRL so I'm guessing the relay is bad.
Crossing my fingers everything returns back to normal. Thank you for your input and help. Normally I'm the one helping everyone else but this one had me stumped!
Vinny

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Nice! :woohoo: Nice catch with the A/F relay, too. Never seen that before, gotta keep my eyes open.