Oops, put this post under wrong forum.

1997 Expedition, 147K. Pulled in the driveway and the engine quit. Engine will crank but won't start. When you go key on, the THEFT light goes on for 2 seconds, then flashes fast for 1 minute, then flashes code 16. Neither key will start it. I can't seem to connect with my OBDII reader. There is a single wire going to a clip (broken) that holds a contact into the lock cylinder, but that just sounds the key in chime. Can anyone help troubleshoot this? I'm about the replace the PATS transponder, assuming power and ground checks out. The only other option I have is to have it towed to the dealer and bend over. Thanks.

 

From 97 Expedition WSM:

 

Thanks for the reply. So this would indicate the PATS transponder is working? I've tested the circuit to the transponder, voltage is ok, ground is ok.

 

If you mean your code reader can't connect to your PCM, then check the fuse for the 12v lighter socket and see if it's blown.

 

Could be as simple as a blown fuse that operates the PCM.

Does the CEL (SES) light come on during prove-out?

 

Yes, the check engine light comes on when the key is turned to run, then goes out, like normal. I checked fuse 15 for the anti theft system, it's ok. I think verifing communication between the transceiver and PATS module and the PCM is next. Can I do that without the STAR tester?

 

And where exactly IS the PATS module? The book says behind the instrument panel, but there's a few module looking things back there. I think I've got the problem narrowed to a break in circuit 914/915 between the PATS module and the PCM, which would also explain why my OBD2 computer can't connect, it's on the same circuit. The wiring from the DLC and the PATS transceiver both go straight up in the dash and disappear, and I can't see where it goes.

 

It could be the chip in your key goes bad. Try another key.

 

No, it isn't. See above quotation from WSM which EXPLAINS the specific indication he has. A bad read of the key's chip will cause a "fast flash" and no code 16.

PD,

Check continuity from the DLC to the PCM for both 914 and 915. Also, check for shorts to ground, to battery power, and to each other. Circuits 914 and 915 connect the PATS module, the PCM, and the DLC in a parallel network as shown in cell 112-01 of the EVTM.

 

Well, I've test all of circuits 914 and 915. Both have no breaks, no shorts to ground or battery, between them, both from and to the pcm, the DLC and the PATS connection C268. I don't know what to do now. Anything else I can check?

 

How much does a new PATS module cost. Looks like I could get a used one for 20 bucks. It would need key reprogramming of course, but at least I could see if the system does anything different. Are PATS modules all the same for cars of that era?

 

[quote=projectSHO89;8751941]No, it isn't. See above quotation from WSM which EXPLAINS the specific indication he has. A bad read of the key's chip will cause a "fast flash" and no code 16.

PD,

My bad, it was clear like day that he said already said that. Well, after few beers my reading comprehension went south....

 

If you can't read straight after a few beers, then you probably shouldn't be handing out vehicle repair advice at those times either.

 

OK, after more reading, there seems to be another connector C269, a 16 pin square thing, that I should test for continuity between it and the PATS connector. Ugh, where is C269? My back and arms can't take much more of this working upside down and backwards up in the dash. .

AND I discovered the vehicle will let me reprogram my keys to a new PATS module myself, with some key on/key off sequences and a lot of waiting. Cha-ching! No dealer involvement! Now if I could just find the problem first!

 

Don't get too excited yet. To program new keys with that procedure, you need to have 2 programmed keys. If you have 2 "good" keys, you can program a third, fourth... If you only have one good key and need another, you still need a dealer or locksmith.
If you install a new PATS module, you'll need the dealer to set up the keys.