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Saxo Problems & Queries If you're having problems with your Saxo and you're after a bit of advice, check this forum out...

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Old 14th February 2021, 22:27   #1
FrenchElectronicsSmh
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Red face Where's the immobiliser unit? (1996 non-keypad)

Hello dear friends,

I'm the owner of a 1.1i 1996 Saxo, that had immobiliser issues for the last 20 years, and the left window motor stopped working recently (see my username).
The car has been bought new by my family way back when, and since then it's changed hands many times, all within the family, so we all have our experiences with it. Getting the immobiliser to work has become somewhat of a dark art, shrouded in mystery and finessing the key and whatnot, just trying a few times, but yesterday just would not work, at all. All family members tried to turn it on, which means its gone off the deep end.
After reading many threads on this forum (thank god it exists) i learned more about these units and how the key code is read magnetically by the ring around the lock. So i just took my spare key, pressed it right against the thing, and then turned over the lock with the other key and voila! Neat. So most likely the immo works fine, key works fine, just the pickup coil has been neurotic all this time, mystery solved i guess.

However i'd like to stop this from happening again, so i also read threads on disabling the immobiliser permanently. AFAIK, just turn on the engine, disconnect the immo black box while its running and you're done. I haven't seen the principle of how this works explained anywhere (guess people just wanna be done with the whole thing), but if i had to guess the immo re-locks the ECU only while turning off the engine, so if you disconnect it, it cant send the signal back to the ECU to lock it, so it just stays permanently unlocked.

However two things i havent seen ever answered in very clear terms and that is:

1. If i ever plug the immo box back in, the ECU becomes locked again. Everyone then keeps talking "oh you have to take it to a dealer to unlock it", but isn't it just back to its original state, able to be unlocked with a key, i.e exactly the way i have it right now, no dealer needed as long as i have the key, working as right from the factory.
Because i've never seen anyone ever say "well you could turn it on like a normal person *or* if you dont have the key have the ecu unlocked professionaly as a last resort.
I understand this is probably because this forum is for swapping engines, so a mishmash of parts has to happen and no original keys in sight? I just want to know this for 100%, because if plugging it back in somehow permanently disables the ECU until looked at by a dealer as everyone dramatically makes it out to be, then this saxo is probably just going straight to the wreckers the moment im not able to turn it on again. Also info that comes in handy for the next guy down the line (and God knows there are many) that searches these threads that has issues with his immo.

2. Where is the box? Seriously, the only thread that has any pictures is this one and i think they speak for themselves. Some describe the general location of it, but i cant see it. Hard enough to get your head under the passenger dash as it is, think i'll crack a vertebrae contorting for 30mins to find anything. That being said, to continue the tradition here's my shitty pic of the underside of the dash
If i have to guess, its somewhere in the upper left part of that photo. The thing with the brown plug is probably the ventilation (btw surprise, also doesn't work anymore!). Is it even in the photo, or do i need to remove parts of the dash or carpet to dig it out?

Any help would be mucho appreciando! Cheers
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Old 2nd March 2021, 18:05   #2
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Really nobody knows the answer to either? :/
For some reason image didnt post in the OP post, so here it is again
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Old 2nd March 2021, 20:19   #3
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The immob box is under the dash, behind fusebox.

The reason you cant just unlock it with the key is you need to reinitialise the ecu, then tell it the new key/immob box key code (four character alphanumeric iirc) using external, dealer-spec software.
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Old 3rd March 2021, 19:29   #4
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Just unplug the immo box with it running to prevent the immo from putting the ECU into 'don't run' state.

If you want to have it back to original, just start it and plug it back in. It will then be back as it was and none the wiser.
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Old 3rd March 2021, 21:52   #5
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Seems like in my last post it didnt embed the imgur image again but..it was wrong anyway because it was a picture of under the passenger glovebox compartment, i recall seeing it in some thread, maybe this http://www.saxperience.com/forum/sho...d.php?t=409203 (i wont embed anymore cause some features seem broken, at least on my laptop)
Maybe some years have it under the passenger, some under the dash. I know some have it in the console as a keypad..

Anyway thanks for the replies!

Quote:
Originally Posted by Gabbastard View Post
The immob box is under the dash, behind fusebox.

The reason you cant just unlock it with the key is you need to reinitialise the ecu, then tell it the new key/immob box key code (four character alphanumeric iirc) using external, dealer-spec software.
Makes a lot of sense, how would one end up in this state though? If i plug the immo back in while the engine is off it will lock and require a dealer to unlock?

So as long as I do exactly in the manner Chipwizards describes it should be fine to go between locked and unlocked with no issues?
It also makes sense that it wont know anything happened if i plug it back in while engine is running, but maybe if its off when i plug it in it senses a disturbance in the force
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Old 3rd March 2021, 21:59   #6
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Quote:
Originally Posted by FrenchElectronicsSmh View Post
Seems like in my last post it didnt embed the imgur image again but..it was wrong anyway because it was a picture of under the passenger glovebox compartment, i recall seeing it in some thread, maybe this http://www.saxperience.com/forum/sho...d.php?t=409203 (i wont embed anymore cause some features seem broken, at least on my laptop)
Now that i re read it, this one also mentions the fuse box. What was confusing me is that fuse box is under the driver's dash side, but passenger keeps being mentioned, i guess i'll have a dig around, im guessing no way to get to it without taking the dash off anyway, i certainly am not that bendy
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Old 5th March 2021, 20:42   #7
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Is your LHD?

Fuse box is above/in front of the glovebox on a RHD car (left hand side A pillar). The immo box is in front of that. It's about the size of a packet of cigarettes. The connector faces the RHS of the car and is a 'lever over' release affair with a little tab to press down to allow opening it.
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Old 6th March 2021, 11:34   #8
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Quote:
Originally Posted by Chipwizards View Post
Is your LHD?

Fuse box is above/in front of the glovebox on a RHD car (left hand side A pillar). The immo box is in front of that. It's about the size of a packet of cigarettes. The connector faces the RHS of the car and is a 'lever over' release affair with a little tab to press down to allow opening it.
Oh, yeah, its LHD. I guess you're right, i should have specified/thought of that!
Makes sense about the box, and i think i have an idea of what it looks like, but that explains why i wasnt able to find it passenger side.

So if its always near the the fusebox, and on LHD the fusebox is LHS of the driver well, then it should be right around there for me as well? Alright, thanks!
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Old 6th March 2021, 15:13   #9
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Here we go, thanks to your description finding it was easy https://i.imgur.com/braO2vp.jpg

Trying to get to it was another story, tried to remove just the fusebox to try and reach for it trough the hole, that obviously didnt work.
Couldn't find any obvious holes to stick my hand trough either so im coming to terms with the fact that there's probably no way to do this other than to rip the whole dash out?
Time to play hide and seek with all the hidden bolts, luckily there's videos on it https://www.youtube.com/watch?v=Y3lZE1Rjeh4
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Old 8th March 2021, 21:55   #10
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Quote:
Originally Posted by FrenchElectronicsSmh View Post
Here we go, thanks to your description finding it was easy https://i.imgur.com/braO2vp.jpg

Trying to get to it was another story, tried to remove just the fusebox to try and reach for it trough the hole, that obviously didnt work.
Couldn't find any obvious holes to stick my hand trough either so im coming to terms with the fact that there's probably no way to do this other than to rip the whole dash out?
Time to play hide and seek with all the hidden bolts, luckily there's videos on it https://www.youtube.com/watch?v=Y3lZE1Rjeh4
I've unplugged them before in-situ but it's a bit of a knuckle skinner job. Certainly doesn't need the dash out.
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