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Longshot on immobilizer

djblurr

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Joined
Nov 8, 2022
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7
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australia
Hey guys, I've got an 02 Prado which has just started having some immobilizer issues of late. I took it to the mechanic and they ruled out anything mechanical and said it has something to do with the immobiliser and that I'd be better off going to an auto-electrician.

When I turn it over, it does crank but intermittedly doesn't start. Sometimes it can be hard to replicate, other times it can take quite a few goes before it works.

I took it an auto-elec and told them what the mechanic said, and they went and just got my keys reprogrammed. Charged me $250 and thought they fixed it. It worked ok for a couple of days (I'd say by chance) and then the issue has returned. I've spoken to another auto-elec who says he's had the same issue on 90 series Prado, and the only way they could fix it was to replace the immobilizer module and the entire security lock set, and then follow some settings to reset and sync it. This sounds like a nightmare because 1) the parts will be hard to find 2) sounds expensive.

I'm not convinced this is the issue yet though. I've been doing some testing for the last 24 hours, and although this has worked so far, it obviously could be just by chance.

I've found if I unlock the car with the key in the door manually, it will start the car first time. I've had success with this in about 10 attempts.

In between my testing of this, I did lock the car and then try to unlock with my remote and it failed. It also worked this way a couple of times.

Any one experience this before? Could my remote be causing the issues?

Oh, I'll also say, I have two keys and the issue has been happening with both.
 
On my 00 Prado the remote is completely separate from the immobiliser. Immobiliser is built into engine ECU I think. The remote is a seperate add on module from Toyota.
 
Ahhh ok, do you think this means its worked purely by chance then and not another fault?
 
Is the remote completely separate from the key? Or integrated into the key?
 
Mine is a single button teardrop shaped thing that is completely separate. That's how the Australian ones are anyway
 
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I'm not sure then. I think the remote is totally separate from the remote though as the remote was an option. The immobiliser is part of the engine ECU.
 
Does the immobiliser go out as soon as you insert the key?
 
Does the immobiliser go out as soon as you insert the key?
If it is going to start it does, if it doesn't then I know it will fail so don't bother flattening the battery with failed attempts.

After messaging you I tried a few more times in a row and I did manage to get a fail by using the key to unlock and then try. Seems it might have just been luck.

Is there any way to test if it is just the transponder rather than the entire immobiliser? How would I even find these parts :fearscream:
 
Key chip is easy to test with both keys.

I'm pretty sure there is a key presence switch in the ignition lock. I just tried mine and the light goes out just after I feel resistance from pushing the key in. See if you get the same result. If yours doesn't go out until the key is fully installed maybe that would indicate the switch.

With the coil this is harder to test but it is easy to get to. I'd start there with making sure wiring and connections are good.

With the ECU this is hard to test without substitution and it's also the most expensive.

I don't think any of these parts would be too hard to come by from a parts place or a scrapyard. But if you want to switch the ECU you'll need to change the locks (at least the ones you want to work) as the ECU, keys, and locks you'll want to buy together.
 
Stand by the car and hold both lock and unlock fob buttons down for 30 seconds to re-synch .
 
Yeah replicated on both. And like I said they reprogrammed both keys but it’s doing it still.
 
I had the same problem with my 01 D4D Colorado. I traced it to the key reader which attaches to the ignition key barrel. this had come loose and when screwed up tight started every time. Might be yur problem, might not but you can try fot nothing.
 
I had the same problem with my 01 D4D Colorado. I traced it to the key reader which attaches to the ignition key barrel. this had come loose and when screwed up tight started every time. Might be yur problem, might not but you can try fot nothing.
I’m not great with cars, could u point me in the direction of something that might help with this heh?
 
Take a look at the plastic surround on the steering column undo the screws that hold it together and you will see the electrical gubbins around the steering lock and ignition wiring then check the connectors for security
 
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