Just bought an 03 Mustang from an auction and took it on a trip. The anti-theft system kicked in and I had to disconnect/reconnect the battery to get it working again. That worked a few times and I thought it would continue to work until I got home where I would get it looked at.

Unfortunately it stopped working altogether and I had to tow it to a dealership. I asked them to disable the anti-theft system altogether but they tell me that's not an option and I have to fix it. A call to my regular mechanic who I trust confirmed that they were telling the truth.

However, I've seen webpages talking about 'tunes' and 'tuners' (I have no idea what that is though) you can get to disable it and referencing Mustangs specifically and I'm pretty sure one page was even specifically talking about the '03 Mustang.

So my question is: Is there a way to just disable the anti-theft system? I'm not worried about anyone stealing my car but I definitely don't wanted to get stranded several states way from home ever again so if there's a way to do it I'd sure like to know.


  • im having the same problem as we speak im not sure if i can bypass it but would like to know really dont feel like spending alot of money at the ford dealer the car starts for about 2 seconds then shuts off an just cranks an anti theft light is blinking – user3181 May 20 '13 at 2:35
  • I've always thought it would be nice to have an open-source/open-hardware ECU with an array of DACs/ADCs and easily swappable wire harness adapters to match up with any vehicle (and appropriate software on the board). :-) Then you could do away with this nonsense (and a lot more nonsense) by just pulling the factory ECU and dropping in one of these... – R.. GitHub STOP HELPING ICE May 20 '13 at 2:45
  • Someone could go through all the effort of erasing the immobilizer from the ECU Maps but it may be easier just to change the transponder key antenna/receiver which is likely the source of interment immobilizer issues – narkeleptk May 25 at 16:45

If you want to bypass your antitheft, you can attach one of your PATS keys inside your steering collumn by the lock cylinder. This will make the car always 'see' a key with a chip. You caqn then use a regular steel key. This is also a 'cheater' fix when installing remote starts on cars with PATS so you don't need to buy a module.

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  • Yeah I read about that somewhere and I actually asked the mechanic at the dealership about it, but according to him it has to be able to communicate with the chip directly 'through' the actual key and not just wirelessly. I can't confirm whether that's true but at least it seems to be working now and hopefully shouldn't go out for another decade and it will be someone elses problem by then :) – Brandon Moore Mar 7 '12 at 7:49
  • Ive done that with my Fords which includes several tauruses and a ranger but havent owned a mustang but can't see why they would have it different on it. – stephi Mar 16 '12 at 17:34
  • Cool... maybe I'll try it out one day when I'm feeling less lazy :) – Brandon Moore Mar 16 '12 at 18:44
  • This does not bypass anything and will do nothing to solve any problems. Your simply moving it from one Area to another. – narkeleptk May 25 at 16:46

The PATS system CAN be disabled completely. A decent ECU tuner or Auto-electrician can do this by modifying the data in the engine ECU. When completed the Engine has no recollection of ever having an immobiliser and will start the engine without looking for the chip in the key or any other immobiliser related part.

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You would probably have to have someone recode your ECU, as they are usually intertwined with the anti-theft system to ensure the engine will not start. I don't think they can really be disabled easily thought. Cars with systems like this can be triggered by bad keys as well, so check that out. The key can and will go bad, and this could make you think the car is acting up.

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  • 3
    Thanks, turned out to be the tranceiver (or transponder?... I forget). I gotta say I'm not real happy about having a car with anti-theft parts that can go bad and can't be bypassed. I understand that may undermine the anti-theft system, but I didn't exactly care to have it to begin with and I literally got stranded and had to sleep in my car on a freaking cold night in TN. Sigh... but I digress. – Brandon Moore Jan 9 '12 at 5:03

If the Mustang is automatic with the 4.6l engine get a computer from a Crown Victory it is 4.6l automatic also and PATs free and the computers are all over EBAY, I put one in a 97 Mustang and solve my PATs problem.

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