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Removing an immobiliser
Norfolkluegojnr - 19/6/13 at 03:19 PM

Not sure if anyone can help on this.......

I want to remove the after market immobiliser from my MX5 - the documentation I have with it is faded so I cant read the model type, but its a TOAD one.

It has a small touch pad, about the size of a 20p piece on the cowl under the steering wheel, and a small circular disc that touches it to disarm it.

Before I start ripping things apart, does anyone have any idea how these things work, and how I can remove it?

Thanks as always!

adithorp - 19/6/13 at 03:51 PM

The "touch pad" will be wired to the immobilser box and then wires from there will go to the ignition and possibly fuel pump circuits and there may be a wire to a door switch and a constant live. All the immobiliser wires will be black and unmarked/unidentified. Follow the wires from the pad back to find the box and then from there follow the other wires to where it's been spliced into the cars circuits. At that point the cars loom wires should be identifiable for you to cut out the immobiliser and reconnect the car circuits.

Shoudn't be too technical but if it's been profesionally fitted it should all be well hidden so can take time to remove.

Norfolkluegojnr - 19/6/13 at 03:54 PM

sounds like a right pain in the balls! I guessed it wouldn't be too simple otherwise it'd be pointless.

I'll get hunting. I take it you can't create some kind of permanent disarm state in the touch pad circuit?

scudderfish - 19/6/13 at 03:59 PM

Glue to RFID tag to the sensor?

Norfolkluegojnr - 19/6/13 at 04:02 PM

quote:
Originally posted by scudderfish
Glue to RFID tag to the sensor?




I did think of that, but knowing my luck it'd drop off. I was wondering if the right kind of resistor might do it? I guess not.

bi22le - 19/6/13 at 04:03 PM

quote:
Originally posted by Norfolkluegojnr
sounds like a right pain in the balls! I guessed it wouldn't be too simple otherwise it'd be pointless.

I'll get hunting. I take it you can't create some kind of permanent disarm state in the touch pad circuit?


Not easily. They will default to immobalise.

Good advice by adithorp. Essentially track the box down and chase the wires. If it just T junctions onto a wire then you can just cut it out. If you see a standard car wire (example red and white) end and then go to your black wire towards the immob box then you know its a cut. Join the 2 red and white wires back together. Done.

If the fitter is clever he will cut a whole section of wire out to stop easy joining. If this is the case use some of the ample black wire to join the wires back up.

Any problems, take photos and post them up.

MX5 and basic immobaliser. I recon I could have that out in 15mins, no kidding!!

mark chandler - 19/6/13 at 05:17 PM

It will have 4 wires that do something, one pair is a break contact, the other a make so just trace back into the loom, disconnect the power and earth and chase the other 4 wires to where they have been cut in. Simples.

DarrenW - 19/6/13 at 05:33 PM

As adithorp says, it really wont be too difficult. Ive fitted them and they are very easy to do. just take your time and reconnect one circuit at a time. Main power will be easy to identify. Leave that connected then as you by pass each circuit just check the car fires up.

For every one wire on the cars main loom that has been immobilised, it will be cut and connected to 2 black wires that go to the main immobiliser box. All the immobiliser does is break or make the circuit - its just a fancy switch. In theory the hardest part should be to find the immobiliser box, although in practice i doubt that will be too difficult. You may need to remove some trim first. The touch pad is the biggest clue as that will show you where the box is by following the wires.

Regardless of how the immobiliser was connected up by the 'pro', solder and heatshrink each of the re-connections that you make. No scotch locks!!! Crimps are ok ish but still no substitute for proper soldered joints.

Im guessing the main and switched lives wil be spliced into appropriate feed wires in the car loom, rather than with the immobiliser circuits where the wire is fully cut and each end connected to a black wire. This is why they are easy to spot usually. The earth should be connected directly to the cars chassis, but may also be spliced to the cars earth loom.

The only way removing the immobiliser can get tricky is on Jap cars as in my experience they dont seem to follow normal logic on the feed wires. Is Mazda wiring typically Jap??

Norfolkluegojnr - 19/6/13 at 08:13 PM

right, update.

I traced the black wire from the transponder thing to the main loom, then to the passenger footwell. It appears to have been spliced into the loom there, but I can only really see two splices.

There is about 5 black wires running down behind a footwell trim piece that I ran out of time to remove - i presume I'm along the right lines?

So once the trim panel is off (should get time at the weekend) this should be fairly simple?

Also dug out the paperwork for the orginal fitting - back in 2001! - but some genius put it on carbon paper, which is now of course completely blank. No clues there!

HOwever, I am enthused by the fact there only appears to be about 5 wires. How hard can it be?

DarrenW - 19/6/13 at 08:22 PM

Do you mean 5 black wires with no traces?

mmmmm, this is interesting. i would assume the immobiser needs a perm live, switch lives and earth. that leaves 2 black wires. beased on the fact that there should be one immobiliser circuit per 2 black wires, this woulod suggest tat only one immobiliser circuit is wired up - not thatcham approved.


Can you post either a picture or say what coloured wires are connected to the 5 blacks? i reckon you are ver lucky and this job will be easier than usual.

Norfolkluegojnr - 19/6/13 at 08:27 PM

Bit dark here now to make much more progress, but let me clarify:

Hard to count but look like 5 black wires, but I can only see two obvious splices into the loom, onto two black wires. Could be more, but its hard to tell.

Once I've got the trim off, I'll take a pic of the unit before cutting anything!

Norfolkluegojnr - 19/6/13 at 08:41 PM

bit more digging. it appears the ECU is kept in the passenger footwell, so i guess there will be more wiring once im in there. I'll take lots of pics and post up.


THanks for your help thus far guys.