P0657-Bad ECM?

just found-out standard operating procedure is to flash all used ECMs. Otherwise, it usually won't start. Guess I just wasn't as lucky. Found a place in town that can do it for $95. We'll see how it goes!

 

Well you learn something new every day -- I always thought that every ECM was mated to the keys of the truck and that unless you had said keys it would never work.

I think I read in the manual somewhere that if you loose both cupped keys you had to buy a new ECM.

 

wow. Looks like I forgot to give an update! lol. Well, I tried to get the ECM flashed to no avail. Turned out to be a faulty unit. They didn't have a replacement available and so I was given a refund.

last week, I tried to do this all over again. I found one for $215! plugged it in, and it worked like a champ. No need to get it flashed.

more evidence to show a used ECM solves this problem. thanks again ratman!

 

Hi there, i'm new to the site. So far its been very helpfull. Long story short, i'm working on a friends tacoma that he was changing his battery on and hooked it up backwards. Your description of the side effects afre dead on... limp mode, high idle, CEL on, code p0657 in the ECM. I replaced all the blown fuses (ABS2, 120A ALT, and all the small ones that popped) and the code kept reappearing. I tested the T-body sensors OK, checked the wiring from the ECM to the t-body OK, That was leading me to believe that it is the ECM as in your case. Funnything though, i put it all back together and plugged the ECM in just so i could move the truck outta my garage and now its just fine. No CEL, no more limp mode and it warmed up and idled fine. I was wondering if you had ever tried plugging your original ECM back in and see what happens?

 

No, I never tried plugging the original back in to see if it corrected the problem. It sounds like RSB did and that did not solve his problem. I think I still have the original ECU but I see no reason to try it, the truck still runs like a champ on the replacement unit I got from salvage.

Does it start consistently and run with no warning lights now that you reconnected it? Disconnecting the battery seemed to clear the problems for one start in my case, but if I shut it off and started again the CEL was on and limp mode etc etc. So while I waited for the replacement I was able to drive the truck by disconnecting the battery every time I started it. I'm assuming you disconnected the battery when you exchanged computers...maybe that's what you're seeing?

Good luck!

 

Thanks for the reply. Yes, i did have the battery disconnected while ohms checking the wiring and the t-body sensors. What you say makes sense because now when i start it the CEL is on and its back to its bad behavior so it must have been ok for just one start because i had the battery disconnected. Looks like i need to find an ECM for my friend. Thanks again for the reply and the great thread.

 

Good info.

I have just replaced my engine, and at my first day the car ran fine. Next day, it decided to stop. I checked all my fuses, checked my fuel pump, everything is perfect. The only problem is that my spark plugs are not getting any juice. I still cannot figure out what's the problem, but I'm thinking it might be a faulty ECU.

I thought when you replace your ECU you have to reprogram your key, or replace your ignition switch. I'm surprised you guys managed to run the truck without doing so. Does the 2004 Tacoma have an engine immobilizer?

 

04 does not have an immobilizer unless its added at the dealer or at the port (lots of options get port installed). easiest way to tell is to look for a blinking red light somewhere on the dash while the key is out of the ignition. No blinking light=no immobilizer. And you are correct, if there is an immobilizer it is the key that needs to be programmed, but Toyota limits how many keys can be programmed so you probably have to take it to a dealership for them to take care of that. I doubt that is your problem though.

Double check your fuses, and also check to see that the fuses have power going to them when you have the key turned to the ON position. Also, does your check engine light illuminate when you turn the key to ON?

 

That explains it. Without the immobilizer you can just plug in any ECU of the same car, no problems.

Yes, I do get the check engine light when I turn the key to the ON position.

Anyway, I solved the problem. I had a piggy back system spliced into my harness from when I had a Supercharger on, and I disconnected it and bypassed the wires, and it worked. Looks like the piggy back system became faulty.

 

P0657, P0604, and P0606 are pretty much a death sentence for your ECU.

Hey guys, for what it is worth, before you go to a salvage yard to get a used one, that usually has no warranty, or a very short one, contact me. I can get remanufactured units, with YOUR VIN NUMBER programmed in, matched to your truck. And from what I have seen in this thread, I can match or beat what the salvage yards are charging for a used one that is not vin matched. They run anywhere from $295-$395 for a 1st gen, but up to $900 for a 2nd gen, depending on the truck.

That being said, there are certain year models and such that DO require additional programming. The 2nd gen trucks with immobilizers will require programming at the dealer. The only way I can properly get a quote would be by VIN. So if you are looking for an ECU for your Tacoma hit me up. I might be able to get you a better deal. Moderators, if me throwing this in here is considered to be not appropriate, please let me know and I will edit the post.

 

Hey i got that code after i got a new ecm that means they sold me a junk one i guess
does that mean replacing the ecm is all i can do

 

hey guys, i bought a salvaged ecu for my 2006 tacoma, it didnt start the truck, i was told after that it needs to be programmed before it can work. can anyone help me out where and how i can get this done.

 

Would you be able to give me the part # for your ECU? I'm converting my 2004 DCSB Tacoma TRD Auto 4WD over to a manual trans, and I need to get the appropriate ECU to do so. Thanks!