Replaced ECM car will not start

LUANASTROUP

MEMBER
2004 LEXUS ES 330
3.3L
V6
2WD
AUTOMATIC
200,000 MILES

I replaced the engine control unit with a used one and the car wouldn’t turn over. I read that I would have to reprogram the unit using the keys from the car it came from, but I didn’t have those. I found this video: https://youtu.be/HQXgbSUQ0Yo that explains how to do it without an old key. I did this and now the car won’t do anything. No lights no sounds. I tried to jump it, the battery is good. What do I do?

5 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

You have to have the chipped key that you are using to turn over the ignition switch to start the car programmed to match the ECU that is plugged into your car. The only places to have this done is either the dealership or at a locksmith. This is stringently controlled like this so that people can not go around stealing people's cars. I am not saying that that is what you are doing, so please do not think I am. I am sure that you are glad that the vehicle's manufacturer has put these controls on who can make these keys so that your vehicle will not be stolen. Let me know if there is anything else we can help you with.

Thanks,
Alex
2CarPros

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Friday, March 22nd, 2019 AT 1:50 PM

LUANASTROUP

MEMBER
11 POSTS

Can I take just the key and the ECU? Or do I have to take the whole car to the dealership? It doesn’t run and I don’t have a way to tow it right now.

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Friday, March 22nd, 2019 AT 2:02 PM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello again,

You should be able to take strategy code from the PCM and the key to the dealership for reprogramming the key. The strategy code is usually a six number alpha numeric combination written in large print on top of the sticker on the PCM. To be on the safe side though, you could copy the whole PCM alpha numeric code and take it with you.

Thanks
Alex
2CarPros

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Friday, March 22nd, 2019 AT 9:09 PM

CLARA CJ HOLLIFIELD

MEMBER
1 POST

I am having the same problem with my 2003 chevy trailblazer.
I will take it that alpha numeric code and my key to dealershio next week. Thanks for the info.

One question, if I tried to start the vehicle after replaced ECM with the old key, will it mess uo the new computer?

Also, I lost my keys a cpl years back and no longer have a key fob. Should I purchase a new keyfob as well?

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Thursday, June 27th, 2019 AT 1:05 PM