CoryMiller

So I am ready to drive me ES300 off a cliff.

Driving home from Vegas one weekend, my CEL came on and it took out my overdrive. I stop at Auto Zone on my way home and they read both Knock Sensors. I knew the harness had been old and brittle so I buy a new harness and 2 new sensors. Replace it all, take it out for a test, CEL comes back on trying to shift from 3rd to 4th.

Dad says it's likely the PCM. Find a junk yard that has the correct PCM, and plug it in. Just as I start to crank, my dad remembers the anti-theft. The anti-theft light still blinks when I turn the key to on. It will not start. It'll crank for days, but will not start.

Does anyone know a way to bypass the anti-theft without have Toyota re-flash the whole PCM? I am tired of not having overdrive and my gas mileage is awful, even though I am only driving it a max of 5 miles a day.

PLEASE HELP!!! I searched and I didn't find many threads that were similar to my issue. If I didn't search well enough, just link a thread in here that will help.

Thanks.

ES300NZ

you cannot bypass the anti-theft system.

- BUT if you want to work with this ECU, you need the Key, and the receiving ring in the steering column and the decoding box which is further down that loom. It's totally possible to do that.

I really doubt it was faulty, but I guess you'd be in a better place to know. I think you gave up to quickly and looked for an easily solution.

- it would be best to reinstall your old 'PCM' (ECU) and try to solve the problem, or take it to someone that can.

CoryMiller

Not sure I follow "giving up too easily." I RE-installed my old PCM so I can drive it to class. It runs, but it's just on 3 gears.

I trouble-shooted the problem and read other people having to change the PCM but never read anything like this.

I'm not sure what other issues can be causing this other than a bad PCM? New sensors, new harness, still throwing the knock sensor codes.

PFB

Did you use OE Lexus knock sensors, or aftermarket? If aftermarket, they are notorious for not being compatible.

CoryMiller

Aftermarket. Used an OE harness. I seriously doubt the sensors are bad.

LeX2K

Aftermarket sensors can be "bad" right out of the box, meaning they are simply not comparable with the OEM parts and you'll keep throwing codes. The ECU doesn't only look for knock, it looks for a specific waveform and if it doesn't see it, it will go into limp mode and set a knock code.

PFB

The few aftermarket knock sensors that do work are the exception and not the rule. And even when one batch does work , it nay not work the next time.

When it comes to knock sensors, get the originals

ES300NZ

well, if the sensors were functioning ok then the ECU would not throw the code.
- I would find some used sensors from another vehicle (same model) and install those.
- perhaps the (both?) pins are pushed back into the plug on the ECU termination end

Another option is that the engine has a fault ?
- is knocking, timing off, bad injector or two,
- worn rods, or pistons or main bearings.
- not all codes which are thrown relate to the sensor being faulty, sometimes its another sensor (Maf failure causing O2 sensor CEL) or a genuine mechanical fault.

CoryMiller

Another possibility I've come
Across, is a faulty ground?