ECU replaced and now will not start (1 Viewer)

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Apr 7, 2006
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I have a 98 that the cruise control will not work and CEL on that requires sensors replaced. I replaced all the sensors and still was having the issue. My mechanic then asked me to purchase a used ECM which I did at ebay. He then said that the unit I purchased is defective since the truck will not start and his friend who is a mechanic at a local Toyota dealership said that 98 and 99 model years does not need to be reprogram. I asked Ebay seller for a refund and he said that it needs reprogramming to make it work. I am asking the experts here to find out who is correct. Thanks for any replies
 
The key needs to be programmed to match the code in the ECU before it will start. Try this, it worked for me on a brand new key. I am not sure how it works on already programmed keys, but worth a shot before dropping 200 bones on a new one.

Transponder Key Programming
 
You won't be able to program any keys without a working master, dealers only install new ECUs that start in programming mode when first powered up and register the first three keys inserted in the ignition. Not surprising that a Toyota mechanic wouldn't have experience with used ECUs.

In the off chance the eBay seller sent you keys with the ECU, hold them up against the ignition ring while attempting to start with your key that fits the ignition.

If they didn't send you any keys, then the ECU will need to be flashed. They edit the hex code stored on the eeprom chip to remove all existing keys and the ECU goes into programming mode. You might find a local locksmith that can do this or you could send off the unit to have it done.

Have the mechanic put your old ECU back in so your truck is usable while you're getting the new one flashed.
 
Well yeah, I guess I should have thought about the whole "not having the master key that matches the ECU" thing. :bang:
 
@nikramos - there look to be a bunch of locksmiths in the Bay Area that reflash ECUs. I'd call around until you get someone that's familiar with Toyotas, or even better, Land Cruisers. Search the forum for "Locksmith Charley". A number of members have used him for keys, ECUs, etc. on these trucks, so he's familiar with our immobilizer system. It may be worth a call to him just for the education or to ship your ECU to him, he's in Phoenix.

Locksmith Charley's TOYOTA Transponder information page                                                                                                                                            
 
Any quality locksmith should be able to help. I only had a cloned master when I bought my LC. IT would not allow for any programming even though it appeared as a master. Locksmith was able to flash the ECU when he came to the house and create a new master and make 2 new keys as well....
 
The 1999 can not have keys made for it's ECU unless you already have a mated key. You must have at least one master key mated to the ECU before you make more master keys so if you got a bare e-bay ECU and it didn't come with a key then it's of no use. Later 100 series CAN have keys assigned to the ECU by a dealer or skilled locksmith.

Search around here and you'll find that if you know how to ask you may get a deal on your 1st early model 100 series ECU replacement because you've lost your keys. (Toyotas design wasn't very consumer friendly so they're understanding)
 
Don't forget that even with a coded key, when power is reconnected to the new ECU you'll need to leave the ignition turned on for a while (6 minutes iirc) then turn off remove and then reinsert the key before the key will work and security light will stop flashing.
 
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Thank you for all the replies. My mechanic took it to another dealer and they had the ECU reprogram. The truck now starts and my mechanic is making sure that the CEL does not come back and cruise control works.
 
Glad to hear you got it resolved. To clarify: your new ECU is now paired to your old keys?

Since there is sparse conflicting information on here about the '99 ECUs, it would helpful to the rest of us to know what was actually done. Can you ask your mechanic for details? Was it actually a Toyota dealer? Or a locksmith? Did they flash the ECU? Or is there another method for pairing keys with used ECUs? Cost? Thanks!
 
Glad to hear you got it resolved. To

Correct labcab my old keys is paired with my new ECU
Mechanic said that he asked his friend who works for a Toyota dealer program my old keys to the new ECU. His friend did it on the side and cost an extra $200. It would have cost a lot more if you take it to the dealer and do a work order.
The new ECU did not cure the CEL so my mechanic drove the car and while the speedometer is reading 65mph, the scanner connected to the ecu is reading 90mph.
He checked all the wires even replaced all the sensors with Toyota OEM. He thinks the 285/75/16 tires might be causing the issue since its bigger than the stock tires. He will check the gauge cluster now. Any ideas what causes the CEL at this point.. Thanks
 
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I'm glad you found a cost effective way to get the ECU going. I'm a little concerned about your mechanic though thinking that a tiny difference in tire size would justify a 25mph speedo error, it's more like 1-5mph.

What are the error codes from the CEL? Which sensors are "all the sensors"?
 
I'm glad you found a cost effective way to get the ECU going. I'm a little concerned about your mechanic though thinking that a tiny difference in tire size would justify a 25mph speedo error, it's more like 1-5mph.

What are the error codes from the CEL? Which sensors are "all the sensors"?
He did agree that the tires will not be the culprit after I told him that I replaced my LX with 33 inch tires too and speedometer only varies 5mph. It is throwing vehicle speed sensors. The 2 sensors in the transmission or transfer case. I left him a msg to ask what codes is it throwing now with the new ECU and will report back. Thank u
 
Search the 80-series forum for P1700. There are a couple threads on issues with those speed sensors. I'm guessing there's a short in that circuit somewhere and hoping a tranny shop isn't in your future.
 
Mechanic said the code is P0500 for vehicle speed sensor. He said that there is also a sensor on the instrument cluster that needs to be check.
 
Check out this thread regarding P0500 First CEL - P0500
Definitely sounds like your issue is the wiring or amplifier at this point from some of the posts in that thread. It also sounds like there is an amplifier in the instrument cluster that could cause it so your mechanic may be on to something there after-all. Read the post there by Slee for a good explanation of why the cluster reads correct but the ECU still throws the code and cruise is off.

Good luck with it!
 
Check out this thread regarding P0500 First CEL - P0500
Definitely sounds like your issue is the wiring or amplifier at this point from some of the posts in that thread. It also sounds like there is an amplifier in the instrument cluster that could cause it so your mechanic may be on to something there after-all. Read the post there by Slee for a good explanation of why the cluster reads correct but the ECU still throws the code and cruise is off.

Good luck with it![/QUOte

Thank you for the link. Mechanic just came to my house and disconnected the gauge cluster on my LX and will try it on the LC. He does not want to order a gauge cluster without switching them first. I told him about the bad ground after reading the link you sent. We shall see. Thank you all for sharing your knowlege
 
My Mechanic switched my 2000 LX gauge cluster to my 98LC to check before he orders another cluster. All lights of the LXcluster lit up connected to the LC after starting it so he disconnected it immediately then switched it. Now my LX throws the same P0500 code from the LC. He clears the code and it still comes back after driving it. Tried disconnecting the ECU fuse plus the battery and still CEL comes back. Does this mean that the LX ECM now memorize the error code of the LC. Not sure what to do at this point since both 100 has the CEL.
 
@Trunk Monkey had a similar issue:
First CEL - P0500

Not sure how it would transfer to your LX...maybe a short in your 98 is frying VSS amplifiers or bending cluster harness pins?
 

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