FZJ80 won't start - help!

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You could write all zeros, but that won't change the functionality, it would just be looking for a key that was programmed with all zeros and that might not even be a valid number to use.

The operational workings are in computer code that is stored in the main CPU. I do think it would be possible to replace the entire unit with a 'fake' unit that didn't connect to a key at all and just told the EFI computer that all is well, keep running. However, this would require reverse engineering the communications between the immobilizer and the EFI computer which ranges from fairly simple to incredibly complex or even impossible.

I didn't understand what you meant about matching the new ECU? What I proposed above is basically duplicating the key codes in the working ECU into the non working one, that should be possible, but it does involve messing with the working one and running the risk of damaging it.

A new ECU with three keys and an ignition lock cylinder was part number 89703-60020 and listed for 424 euros. I'm not even sure this part is available from Toyota any longer.
Thank you!

That answered my question exactly!

Yeah, I started down the same path you had already stated about the new ECU.

Thanks again!
 
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OK, well based on the last few posts, it sounds like a bad idea to let the locksmith near the borrowed ECU if there's a possibility he could alter or damage something by attempting to read the chip. Not going there!

I don't really want to consider this next option either, but... theoretically, would these ECUs all be identical, with the only difference being the info stored on that EEPROM chip? If that's a yes, then would I be correct in thinking that, if the chip in the borrowed ECU was removed and installed in my ECU, and subsequently my truck started with the original ECU fitted and using the borrowed key matching that chip, then this would prove beyond doubt that my ECU is OK, and the fault can only be in the programming of my original chip or the locksmith's inability to create a key that will communicate with it (most likely the latter)?

As stated, it's not really something I want to consider because it involves tampering with the working ECU, and the more I'm finding out about this system, the more I'm realising that a working, paired key and ECU is like gold dust. Something that is clear, however, is that buying the ECU available on eBay probably doesn't get me any closer to a solution without the matching key for it. Other than, I suppose, it would provide me with a second bite of the cherry if I did decide to have a go at dis-assembling mine to attempt to re-program the chip.

I'm wondering about the possibility of buying the borrowed ECU from the owner and having the key copied so that it will physically start my truck, as sbman suggested earlier. Don't know if that's possible, but the off-roader from which I borrowed the parts is in a pretty sorry state and looks to have been sitting in the owners yard for many years untouched. He admitted to me that he's not sure if he'll ever do anything with it, so maybe it's a possibility?

sbman - please clarify something for me: if I let the locksmith have a go at copying the info from the working key onto a chip that can be inserted in the key he's already made that physically fits my truck, is there any way that the copying process can damage the original key? I'm hoping you can tell me no to that, in which case I might ask him to do that and try it - if that key then starts my truck, at least I then have a workable solution for now, even if it ends up being the case that I do have to give the borrowed ECU back. At least it buys me some time to investigate other solutions. Although, I have to say the idea of a new ECU & keys from Toyota at £400+ doesn't appeal! And I'll bet they're NLA anyway.
 
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There should be no harm done by having the key duplicated. The OEM keys were read only and can't be written to. If he is able to tell you what code reads from the key, that could be very helpful information if you decide to probe deeper into this rabbit hole.

There is another, non invasive solution to get the data that goes into the EEPROM chip. There are devices that will record digital conversations in circuits call logic analyzers. They used to be multi thousand dollar devices the size of washing machine but now they are USB devices that plug into your computer and are the size of deck of cards. However they aren't all that cheap. Logic Analyzers from Saleae - #1 with Professional Engineers An 8 channel one is $400. But with that device, you can clip onto the chip's pins in-circuit and have it record the conversation as you start up the truck. It's like a voltmeter in that it doesn't affect the circuitry, it only watches the signals. Then you know exactly what it read from the chip and where it read it from. Then you can use that information to program any other EEPROM to have that same data in it and 'duplicate' the ECU without having to tear the working one apart. If I wasn't so far away, I'd be happy to bring a tool like that by and help you do that.
 
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I've just returned from the locksmith's after asking him to program the chip in my 'new' key to the same settings as the good borrowed key - and having tried that one, the truck starts (with the borrowed ECU plugged in, of course). So at least now I have a key that I can put into my ignition lock and start the engine as normal - for as long I have the good ECU. So this seems to prove that it must be a lot more straightforward to simply copy an existing key than it is when you have no working key. But we probably already suspected as much.

I have asked the guy selling the ECU on eBay if he happens to have the original key that started the truck from which the ECU came - but I'm not holding my breath.

sbman - yeah, we're only a few thousand miles away, so just let me know when you're on your way and I'll put the kettle on! Or put the beers in the fridge, whatever's your preference. Seriously though... just along the road from the locksmith's shop is a guy who repairs anything electronic - TVs, DVD players, Hi-Fi equipment, stuff like that. His shop's been there for decades, and I have used him once or twice for the odd repair and found him to be OK. Do you reckon someone like that would have the equipment and knowledge to do what you're talking about and effectively create a clone of the existing chip in the good ECU and write the same info to my ECU, thereby creating two identical ECUs that would both work from the same key (electronically speaking)? Would someone repairing electronics for his living have one of the logic analyzers you referred to? I do prefer the idea of being able to copy the good chip in a non-invasive manner, rather than having to remove it from the board. Although, I imagine it's simple enough to remove if that's your day-job?
 
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I've just returned from the locksmith's after asking him to program the chip in my 'new' key to the same settings as the good borrowed key - and having tried that one, the truck starts (with the borrowed ECU plugged in, of course). So at least now I have a key that I can put into my ignition lock and start the engine as normal - for as long I have the good ECU. So this seems to prove that it must be a lot more straightforward to simply copy an existing key than it is when you have no working key. But we probably already suspected as much.

I have asked the guy selling the ECU on eBay if he happens to have the original key that started the truck from which the ECU came - but I'm not holding my breath.

sbman - yeah, we're only a few thousand miles away, so just let me know when you're on your way and I'll put the kettle on! Or put the beers in the fridge, whatever's your preference. Seriously though... just along the road from the locksmith's shop is a guy who repairs anything electronic - TVs, DVD players, Hi-Fi equipment, stuff like that. His shop's been there for decades, and I have used him once or twice for the odd repair and found him to be OK. Do you reckon someone like that would have the equipment and knowledge to do what you're talking about and effectively create a clone of the existing chip in the good ECU and write the same info to my ECU, thereby creating two identical ECUs that would both work from the same key (electronically speaking)? Would someone repairing electronics for his living have one of the logic analyzers you referred to? I do prefer the idea of being able to copy the good chip in a non-invasive manner, rather than having to remove it from the board. Although, I imagine it's simple enough to remove if that's your day-job?
An old school TV tech should certainly be skilled at removing and reinstalling electronic components. Whether that person is also skilled at digital analysis or not I couldn't say, those kinds of tools and skills aren't necessary to repair older stuff and the new stuff is so integrated that it hardly applies. Maybe your best move is to see if that person can desolder your eeprom from your 'bad' ECU and install a socket and plug the chip back in. Share some photos before and after and we'll see how the job looks. Once that is done we can do some fiddling with an eeprom programmer on your bad unit before you touch the good one.
 
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By the way, your success in getting the key duplicated means the locksmiths key creating tools work just fine of course. I suspect his tool that reads the code from the ECU isn't reading from the proper location or format for your particular immobilizer. The manufacturers tended to change things up specifically to make life more difficult for people trying to bypass the system. Even @cruiserdan truck immobilizer may store the codes differently internally since it's a slightly different part number. Even if the internals look identical the programming can be slightly different.
 
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By the way, your success in getting the key duplicated means the locksmiths key creating tools work just fine of course. I suspect his tool that reads the code from the ECU isn't reading from the proper location or format for your particular immobilizer. The manufacturers tended to change things up specifically to make life more difficult for people trying to bypass the system. Even @cruiserdan truck immobilizer may store the codes differently internally since it's a slightly different part number. Even if the internals look identical the programming can be slightly different.
OK, got that. But as both ECUs I have here (and the one on eBay) have exactly the same part numbers, is it a safe assumption that they're identical from a hardware perspective, and the only difference would be in the programming of the EEPROM. Would either of the other chips in there contain differences, or do you think that all of the novel data would be on that one smaller chip - the 93LC66 that we've been discussing?
 
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Right, that confirms what I thought.

Unfortunately, the aforementioned electronics repair guy doesn't seem very keen to get involved for whatever reason. Went to see him earlier and showed him my original ECU and discussed what we had planned, as far as the idea of removing the chip and converting it to a plug-in arrangement. First of all, he told me he didn't have any of the plug-in adapters for that type of chip which he'd need to make the conversion. But he then went on to say that this type of automotive circuit board is covered in a varnish after manufacture to seal it from damp in its operating environment. And he seemed to think that may cause problems when it comes to removing & replacing it. Basically, I got the impression it was simply something he didn't really get involved with - and probably doesn't want to either. I guess that's fair enough if it's not really his area of expertise.

So, back to the drawing board. I think I may have to put this on the back-burner for now while I investigate what the options are. At least I know I can start my truck to move it in or out of my workshop as other (paying!) work dictates, and that was my first objective for the moment. And who knows, maybe the owner of the borrowed ECU will agree to sell it to me if I wave a suitable wad of cash under his nose?

sbman - just one final question for now if I may (and apologies if we've already covered this, but it's very long thread now): does any of the info you have access to tell you if the UK diesel models (or, indeed, any other model) used the same immobiliser ECU as mine? There are a lot more diesels here, so if they had the same ECU, it will greatly increase my chances of finding an ECU with a matching key from a breakers' yard. Of course, it's bound to be the case that they're different, but maybe worth checking?
 
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A '96 VX with 1HDFT diesel did use a very similar looking immobilizer unit, part number 89702-60020. However, the vehicle did not have an EFI computer to talk to so it includes some circuitry to run a 'valve' which I assume shuts off the fuel to the diesel. It uses the same part number for the transponder keys as your gas model.

So, I don't think it would be a plug and play solution, no. However, if you could get your hands on a known working diesel ECU and key combination for purchase, I'd be happy to do the hacking portion of things on it along with your non working ECU and see if that makes it play nice or not. It might not since they are slightly different models, but you never know as long as they have the same EEPROM in them. You could post me the parts and it would be fun to have a go at it, and that wouldn't risk the known working parts you have on loan.

As for buying the parts you have on loan, that's a good option, but it does completely brick the other vehicle.
 
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So, I don't think it would be a plug and play solution, no. However, if you could get your hands on a known working diesel ECU and key combination for purchase, I'd be happy to do the hacking portion of things on it along with your non working ECU and see if that makes it play nice or not. It might not since they are slightly different models, but you never know as long as they have the same EEPROM in them. You could post me the parts and it would be fun to have a go at it, and that wouldn't risk the known working parts you have on loan.
That is a very generous offer, thank you. Let's hope it doesn't come to that, but it's very reassuring for me to know I have someone on-board who understands the electronics involved should I run out of options for any other kind of solution.

Yes, of course, I also realise that if the owner of the borrowed ECU were to sell it to me, he's kissing goodbye to being able to ever get that truck running again. Which is why I don't really want to ask, but if I do, I'll be sure to put no pressure on him whatsoever and would only buy it from him if he was absolutely comfortable with letting it go.

Maybe another solution will present itself in the meantime...
 
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Paul,

I’ve been watching this thread from the beginning, and I’d say that if sbman ever flies to merry old England, it’s your “shout” at the pub that night.

Sbman has been level-headed about the immobiliser from the very beginning, and has brought some serious old school electronics skill to bear. It’s nice to see this sort of thing play out just like an expert predicted.

This has been just about the most interesting tech thread I’ve ever read, in spite of its lack of application to my vehicle.

Good job, both of you.
 
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...and I’d say that if sbman ever flies to merry old England, it’s your “shout” at the pub that night.
Absolutely! Agreed 100%.

Glad you've enjoyed the thread too. There were parts where I wasn't finding it particularly enjoyable! However, I'm cool with it now that we've got to the bottom of the problem. Just gotta find a matching ECU & key now and it's sorted.
 
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Just to finally close out this thread, I thought I'd update those who contributed and let you all know how the matter was finally resolved.

I had no luck whatsoever finding another immobilizer ECU with a matching key. The only offer I got was from a guy here in the UK who breaks 80s, but he would only sell me the full lock set with the ECU & keys, and he wanted a chunk of change for it. I've also read some bad stories about him, both on here and from other sources, so was reluctant to go that route. I had him in reserve as a last resort if all else failed! I did find one or two ECUs on their own, but without the matching key, it didn't get me any closer to a solution than what I already had i.e. my own ECU, but without working key.

There was one auto-locksmith type guy who I mentioned way back in this thread who had helped a friend when no one else could get him going. But I was struggling to pin him down to have a go at it, and then we had the Covid lockdown, so that was that for a while!

I finally managed to get him to agree to take a look at it a few weeks ago, so I sent him my original ECU and the dead key. Left it with him for a while, and when I spoke to him, he told me it was sorted. After all this time, I couldn't believe it! So when the parts arrived back with me (with two new key chips, so now I have a spare!), I was somewhat apprehensive when it came to trying it out. But after removing the borrowed ECU and refitting my original one, and fitting one of the new chips to the key, it fired up no problem. Tried with the second chip, and that worked too. Yeehaaa! Finally... sorted.

The cost? £100 ($125). I can't complain at that, considering I was pretty much out of options, beyond the main dealer route, and they'd have relieved me of a lot more than that to sort it I'm sure.

So, once again, thanks to all those who contributed - it is much appreciated.

Now I have a knock sensor fault code, but that's another story...
 
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