ihiryu

iTrader: (7)

Hey guys, sorry I'm a SC'er and I've finally gotten my dream daily, an 98 GS300. I bought it for pretty cheap because the previous owner said it had a bad ecu. Which is does.

So fast forward to today, I got my new (used ecu) today, plug it in and of course it doesn't work.

I can now use my scan tool so that's a great sign.

So here's my problem, the closest dealer to me is over a hundred miles away, and it'll have to get towed there.

What I need to confirm is, I just need to get the key programmed correct? Or does the ECU need to get reprogrammed also?

I have the master key, no valet or anything though.

Thanks
-Steve

GS4_Fiend

iTrader: (22)

yes you are gonna need to reprogram the key also reflash the computer.

ihiryu

iTrader: (7)

That's what I figured, I called the Lexus dealer, and the service manager didn't seem to know what I'm talking about.

Could I just replace the key cylinder and key?

GS4_Fiend

iTrader: (22)

The key cylinder is is not the problem. The key has a chip inside that communicates with the ECU. You must reprogram and reflash the computer because you got a different ECU

ihiryu

iTrader: (7)

right, but if I swap the ignition cylinder, key, and ecu from the donor car, it should work correct?

ntran18

iTrader: (27)

I assume 'doesn't work' means the car cranks but won't start? The transponder, the electronics of the key, is tied to the engine ECU. It won't start if it doesn't receive the right code from the key. When you insert the key, the security light by the dimmer will stop flashing if it senses the right code.

I have a full re-key kit with ECU if you are interested, ie keys, lock, & ECU.

ihiryu

iTrader: (7)

Sorry yeah, cranks but doesn't fire.

PM me with what you're looking to get for it. That's all I'll need correct?

ntran18

iTrader: (27)

Your replacement ECU should have come with a transponder. It's located in the head of the typical keys with the lock, unluck, & trunk button. If you didn't get that with the new ECU, the ECU is useless. So you have a few choices now. Once you have 1 master key recognized by the ECU, you can easily add more. This is assuming that the ECU is the issue here.

1. Get the ECU programmed to a key. There are vendors on Ebay offering this. You would have to send them your ECU & transponder. I don't have any recommendations.

2. See if Lexus dealer can do the same as #1 but they will probably want you to bring in the car as well.

3. Get another ECU WITH transponder. You will just need to swap the transponder in the key head. No need to change the key cylinders. If the security light goes out when you insert the key, the car is ready to start.

4. I have set of 3 keys, 1 transponder, ECU, lock cylinders for front doors, glove box, & trunks. (I am bias toward this option) You can check the part # in the pic to see if it matches your original ECU or check with the dealer to see if it is compatible.
https://www.clublexus.com/forums/2ge...-clearing.html

ihiryu

iTrader: (7)

unfortunately, your P/N isn't what I need, I've been trying to contact the yard I purchased the ecu from to get the key for it too.

ihiryu

iTrader: (7)

All right, so I've got my new ecu and Key today. I took my key apart, and swapped the fobs out.

I put in the new ECU, and still get the immob light flashing when I put the key in the ignition.

is there something I'm missing??

99 GS3

iTrader: (14)

Lots of misinformation here about the immobilizer. There are 3 things that have to happen not just 2. There is a security ecu in the cabin that talks to the key. The engine ecu does not talk to the key directly.

It's when people get new key or swap keys from other lexus vehicles that you have to deal with the transponder in the key.

But since you have the key for the car your scenario is the same as people doing engine swaps and using a different ecu.

This is the communications path. Keyfob tells Security Ecu it's coding, then if that checks out the Security Ecu checks the Engine Ecu's code, if it matches what is programmed in the Security Ecu then it allow the Engine Ecu to start the car.

There is NEVER any reprogramming of the Engine Ecu for anything at the dealer or otherwise, they are either good or bad, and get thrown away..

What does need to be reprogrammed is the Security Ecu, it just needs the code from the new Engine Ecu set so it matches.

This can be done by any local locksmith that has the Toyota Flash kit, The service takes 10-15min and is typically about $125-$250 depending on your area. The dealer can do it but they usually like sell new key packages w/ ecu.

The sellers that sell used keys and state it comes with the ecu mean the Security Ecu. If you had the Security Ecu from the same car you got the Engine Ecu from, and you got the Key as well, you could then take the transmitter from the keyfob put it in your keyfob, install both ecu's and the car would start with no reflash.

All you need is to call all your local locksmiths and ask if they reflash toyotas, and you'll be set. There is no special lexus anything it's all done with the standard toyota kit.

ihiryu

iTrader: (7)

Thanks for clearing that up!

So with that being said, if I got the security ecu it should work?

I'm going to call around when I get the chance, I also plan to call toyota to see if they can do it, since it's one and the same right?

Ninja Edit

I put my old ecu and key back together, and the immob light is still flashing! Any ideas?

99 GS3

iTrader: (14)

You would need all three, the security ecu, engine ecu, and keyfob from the same car the engine ecu originally came from.

Hopefully the battery has been disconnected while you did all that swapping. If not you may need the locksmith to come out anyhow.

Unplug the battery for 20-30 min and try again..

What was the problem you were having with the ecu in the first place? they rarely go bad.

ihiryu

iTrader: (7)

It was bad, OBDII reader wouldn't connect to it. I put the new ecu then I had connection to the OBDII scanner.

I was getting immobilizer code (didn't know they had codes) from my Matco Scan tool.

99 GS, do you happen to know where the security ECU is at (location?) and what it looks like?

ntran18

iTrader: (27)

There is no security ECU. The engine ECU handles security as well. See that attached for parts location.

When you inserted the key and the security light didn't go out, that says 1 or 2 things. 1 that is not the right transponder and/or, if it is the right transponder, the code is not received by the ECU.

You can look here for diagnostic tips and additional info. It's under engine immobiliser system. This is in the GS FAQ.
http://bahamutcars.free.fr/workshop/...nts/index.html