Understanding PATS

[XLTrunner]

In my effort to determine my options with my ignition key issue posted on another thread, I've been trying to understand exactly how PATS works among the various integral components; i.e. chip key, transceiver ring, control module and PCM. Digging thru old threads on here seems to confirm few people really understand how the process is carried out. I found this article online that seems to explain it better than anything I was able to find.

Ford PATS Antitheft System — Ricks Free Auto Repair Advice

If I am to understand this article, the PATS control module is what ultimately confirms the chip code and then sends the "go ahead" signal to the PCM for activation of the start & run process. If that's the case, could a person take the cylinder lock w/key, transceiver ring, and PATS control module from a donor vehicle of same year/model, and simply swap them into their own vehicle and the PCM would accept the signal to start the vehicle without having to be re-programmed? Hoping someone on here has some extensive knowledge or experience to confirm or dispute this.

 

[J_C]

Yes but you don't need the transceiver module. It is not key-specific and holds no programming itself.

Then you will do all the work, twice to also remove these parts from another vehicle, but not have the same key able to open the doors and hatch too.

I would back up a bit. First I went out and checked my '98 and it does turn backwards to accessory position, but it was a bit stiff to do so, and for one moment it got stuck and wouldn't go. I kept turning it back to accessory and to off again several times and it loosened up a bit, now it does it much easier. I probably hadn't put it in accessory in over a decade.

This leads me to wonder if you can finesse yours into working with a lot less effort. First, I would take a hair dryer and point it at the ignition cylinder hole, without the key in... not trying to get it extremely hot, just nice and warm, then would try the key.

If that wasn't enough, I'd spray WD-40 into it and then try the key. I'm thinking it may be a little potmetal corrosion or dried up grease, there is definitely a detent of some sort that the mechanism has to travel past to get to accessory position.

If that alone wasn't enough then I would pull the lock cylinder out and look at it to see if it is damaged like the shaft on the end, and liberally spray the heck out of it with WD-40 then shake it out, then spray with a light oil, shake excess out. I'd examine the mechanism behind it, maybe that needs a squirt of light oil or a slight poke with a screwdriver to nudge it free? Then I'd put the lock cylinder back in to try it.

I guess I could see the benefit in grabbing the transceiver module if you're pulling parts anyway, just in case you damage your existing one while working on this, then you have a spare.

 

[XLTrunner]

Appreciate the helpful tips. I'll give them a try and see what happens. I've never really spent much time trying to understand PATS aside from the basics and curiosity just has me wondering how it all works together in case I should need to do repairs either now or in the future. I'm just not one to be dependent on someone else to fix something if I haven't pursued all options of doing it myself. Just thought having the opportunity to grab some parts off this clean same year/model donor vehicle while they're available might be prudent as future insurance if they would work without additional cost of reprogramming. Aside from time spent to pull and reinstall them (I've got lots of spare time these days), the cost of parts would be far less than a locksmith or dealership...and, I will have furthered my education on the inner workings of this truck along the way. As for now, it's 0 degrees out this morning and this will have to wait for a warmer day.

 

[MrQ]

Take a look at this.

Solved - Everything you wanted to know about PATS.

Also FORScan has added ability to program PATS:

How to use PATS Module Initialization function - FORScan forum

 

[XLTrunner]

In that first thread referenced, right off the bat they make no mention of the separate PATS control module located behind the passenger side airbag on '98's (and, possibly subsequent years) that confirms the key code and authorizes the PCM to proceed with starting the truck and allowing it to run. It's possible they eliminated that module soon after and incorporated the signal confirmation directly into the PCM. But, this is the kind of stuff that adds so much confusion to understanding the whole process.

Right now, I'm leaning towards just letting things be if I can't get the key to turn backwards to the Accessory position. Lived with it for 8 yrs so far....

 

[MrQ]

In that first thread referenced, right off the bat they make no mention of the separate PATS control module located behind the passenger side airbag on '98's (and, possibly subsequent years) that confirms the key code and authorizes the PCM to proceed with starting the truck and allowing it to run. It's possible they eliminated that module soon after and incorporated the signal confirmation directly into the PCM. But, this is the kind of stuff that adds so much confusion to understanding the whole process.

Right now, I'm leaning towards just letting things be if I can't get the key to turn backwards to the Accessory position. Lived with it for 8 yrs so far....

I believe they incorporated it into the the PCM in 2001. PM @NICE59FORDF100 if you want further info. Guy disassembles PAT's systems for fun in Explorers...********* .

 

[XLTrunner]

So, it does seem like on the '98-'00, it's not the PCM afterall that is re-programmed as everybody states...but, rather the PATS control module. I know it sounds like splitting hairs...but, for the DIY-er swapping parts, it could mean the difference between just swapping a donor PATS control module with the matching cylinder & key and having to pay someone handsomely to re-program the PCM if a new lock/coded key is installed. Anyway, thanks for that contact info. Sounds like just the guy who could help me make sense of it all.