JRockZ

Hello everyone,
I'm looking for a little insight on my 94 ES300 138k that I bought knowing the ecm is bad. Odd thing is the car runs and I drove it 20mi home (somehow) but the last few miles were scary as it didn't want to go very good.
The previous owner (1st owner) had a friend at a Lexus dealer diagnose and check everything. I've also been here reading posts for the last few months and the diagnosis checks out the problem is for sure the ecm.
It seems my best bet is to send out the ecm however that's about $200 I don't have and I'm not sure I want to spend,,, I've read everything involved with the ecm replacement and reprogramming of a USED ecm (and key) and know I could do that much cheaper than having ecm repair done but really not sure I even want to now as either way I'll have more into the car than it's worth and if I do fix it then what's to say alternator is still good, water pump still good etc... If that makes sense.
I really wish there was an ez cheap fix to even see if I want to keep or sell the car as is. Btw I have 20+ years of shade tree mechanics and I'm not an automotive dumbass!
So Anyhow not sure what I'm looking for as far as replys go but maybe someone knows a trick or two?
Presently the car runs fine for a little while (undrivable ) then suddenly it dies and or gets to a point where if I accelerate any it just shuts the car off, it will restart and run at idle but dies when put in gear or touch the accelerator pedal. After battery is disconnected awhile it will again start and run fine, sometimes for 30sec to a min or even up to 5mins but then it dies again with same issues. When I first got the car it was good but did die when a/c on or I guess depending on the day of the week,,, I think I got really lucky that it made it home it has not been streetable since.
thanks for any input or comments here's a couple pics she still looks pretty good for the most part






Thanks
JRockZ

JRockZ

I guess i forgot to also ask,,, from this post https://www.clublexus.com/forums/es-...t-es300-2.html what does mean exactly? the numbers are on the ecm itself?

Thanks,
JRockZ

mitmaks

I would send out your ECM to have it rebuilt. I had our redone years ago and it still runs fine. Didn't have to mess with key or anything as the guy takes your OEM ecu and fixes it.

JRockZ

Thanks Mit I agree that's for sure what I should do,,,, however on a limited budget it's taken me 7 months to pay $500 for the car, so another 3-4 months to "POSSIBLY" fix the car just stinks!! Wish I could just borrow/test another ecm to make sure that everything else is in good shape! The car will not stay running when battery is disconnected while cars running so not sure if that's related to the ecm or if the alternator is also shot. Then what if something else is shot too and so on and so on! Lol I guess I just have to decide if I should continue with it or just worry about my present daily.
thanks for your reply!
Thanks,
JRockZ

PFB

<br /><br />One should NEVER, EVER, disconnect a battery while the car is running. There is a good probability of damaging sensitive electronic components by doing that.<br /><br />You can also very easily blow your alternator.<br /><br />It's a meaningless test anyways.<br /><br />Good luck with your ECU issue. Hope you get it resolved quickly at a reasonable price. <br /><br /><br />Phil

JRockZ

Thanks, and yeah I forget how fragile foreign cars can be, drove my Monte Carlo SS without a battery so many times it's unreal and never hurt a thing! By far not a meaningless test I know many that have and not had issues, and regardless the cars already got problems don't think there's too much more that could really harm it! I'll get it sorted somehow someday I guess
Thanks,
JRockZ

PFB

If your handy with soldering, and de-soldering, than one option you could consider is buying an ECM repair kit and either fix it yourself or have someone local fix it go you. It's most likely capacitor issues, and these kits include all the capacitors you'll need. Usually less than $50. Shipped. Do a Google search to find the right repair kit for your car. There should be some YouTube videos on the repair process. I think I also saw a video somewhere on this site but for a different Lexus model. Most ECM problems are capacitor caused.

Phil

JRockZ

Awesome! Thank you Phil,,, I was going to mention at some point that it probably is the capacitors in the ecm,,, I have replaced those before on a motherboard but if they are really small it's to hard for me! I'll do some research thanks again!
Thanks,
JRockZ

PFB

Hope it works out for you, and please keep us posted with the outcome.

Not a good day in Texas today. Sorry about what the mass shooting there. I'm sure I'm speaking on behalf of ALL Canadians. Horrifying.

Phil

JRockZ

Hey Phil, or whoever cares.
I decided i'm just not good enough to solder in capacitors,,, I finally did pull the ecm all the way out and cracked it open and sure enough,,,,,,,

There it is caps were popped so I took it to a place near me (Auto ECM in Grand Prairie, tx) and for $225 they fixed that sucker right up! the diagnosis was "Faulty Voltage Regulator Circuit" now i'm not sure if they also replaced all the caps or if the caps were what caused that or what (Right there is one they would have to replace for sure, I don't know the condition of any others in this unit). All I know is they give a lifetime warranty to the person who had it repaired so i'm golden if I keep the car.

So now the bad news,,, it's still not charging the battery from the alternator so now I have to figure out if it is the alternator or if it is something else like regulator or maybe a bad fuseable link or something? OBVIOUSLY if the Voltage Regulator Circuit was the issue in the ECU then most likely the regulator on the alternator is also shot! but i'm now at the maximum dollar amount I want to spend on this thing! I've got $736 bucks into it and i'd probably be lucky if I could sell it for that,,, but what's a used alternator/regulator cost? 40 bucks maybe? so maybe I should just do that i'm torn because I don't think i'll ever put the car in my name and drive it, i'd rather sell it as is and save a little more and find me a good old Chevy or Pontiac something or another to tinker with.

Well anyhow for people that are having odd issues with their ES300 I just thought i'd say check your ECU for popped capacitors! and if you need a place i'd definatley recommend Auto ECM in grand prairie.
THANKS!
JRockZ

JRockZ

In all my searching for answers on how to fix this thing I was given a ton of documentation on this car, wiring diagrams, electrical system, technical training guides, transmission break down, engine breakdown, srs system, a/c system ect..ect...... bla bla bla.....
I'm attaching the body electrical system in .rar/pdf format incase anyone needs it (if this is not allowed for some odd reason mod may feel free to delete.) maybe someone could use it for something,,, maybe this is already posted somewhere else I got it through a friend that got it from an ex Lexus tech I think, or that's what he said anyhow.

Thanks,
JRockZ

MichaelPm

I have the same issues with my ES 300 even made a post about it. Will run fine then wont run at all if it dies start it idles like **** i touch the gas it dies right away.I had a battery light on i replaced it .Ok then battery light came back on got an alternator fixed that went to leave the shop and it ran like **** .Then they couldn't find **** wrong with it .Then it left me stranded wont start Im thinking ecu ,it wont connect to obd scanners sometimes only when its running bad ,when it runs fine it connects ,and throws no codes, but a speed sensor ...lm so glad you posted this, I only saw other Lexus models having this issue,I have a 96 Es300 200k on the dial ran great 2 years until that battery light came on 2 times. but was certain the ecu was the culprit. Now I would bet cash its the ecu. But their is plenty of people who will repair them on Ebay just search ecu repair .I heard they do a good job it is real shops they just advertise on Ebay of course. Some claim a refund if it is ok. But a lifetime you cant beat that I may contact them also

MichaelPm

Was my Ecu.-I knew what it was before my very skilled mechanic .Then again It could have been something else. I just said its prob the Ecu .from reading this site. On EBay you can get it fixed cheap. I used SIA Electronics in Illinois their name is zkboys on Ebay.They were fast and did a great job. I almost didn't use them because oif a review. Then I thought they been open 20 something years that was just some bitter idiot lol.