Pcm-pats problems to anybody that can help

[kevinvug]

Electrical problem
1998 Ford Explorer 6 cyl Four Wheel Drive Automatic 130000 miles

Having trouble starting the vehicle. Took it to my mechanic and he changed the PCM on it and had someone come out from the dealer and flash it. Still doesn't start. Then he said maybe because the door handle did not work from the inside drivers side that miight have something to do with the anti theft going off. Still will not start, then he suggessted that the punch in door code would have to be used to help reprogram. Didn't work. I was able to get the vehicle started if I unplugged the PCM and the wiring harness for the injectors and the battery and 10 minutes later it would start. Put a new ignition coil in and made sure the firing order was correct. But now it just will not start. What would you suggest?

 

[my98nnj]

What would you suggest?

Find another qualified mechanic.

 

[kevinvug]

I guess the previous owner had already spent $3500 at the dealer with similar problems and I'm not sure I want to take it in if it's going to cost a fortune.

 

[Cobraguy]

My God. For $3500 I could have replaced the engine, ECM, wiring, etc etc. Shoot, I could have bought a new '98 Explorer! If I spent that kind of money and didn't fix it, there would be some serious discussions going on.

Anyway, back to your problem. Unfortunately, you didn't describe in enough detail what the issues are...nor what has already been done. (a ton by the sound of it) This may be one that takes some time from a QUALIFIED technician.

 

[Turdle]

Ok
There is a transponder in the key-a receiver in the steering column and a pats ( passive anti theft system) module in the rear driver side cargo area-under the interior panel.

I don't think the new PCM will recognize the old pats without a dealer reflash.

Ok, you did this, now what?

seems like a lot of shotgunning has gone on, and new problems could have been introduced-
I suggest installing the old pcm, and we go from there. PCM's rarely go bad.

You mention no start.
Do you hear the fuel pump when you first switch the key on?
Does the "check engine light" illuminate with the key switched on?


Have you checked-replaced the crank position sensor-Does it have compression-spark and fuel?

I'm suspecting the fuel pump circuit, and Crank sensor circuit. These are the most common problems which cause a no start.

Also-
The relay connections within the power distribution box can cause issues like this.

 

[kevinvug]

It was brought up that there might be a problem with the key and I did go back and forth with my mechanic about using the original key that came with the vehicle and the replacement. The PCM that was installed was used and was flashed by Ford. And yes I can hear the fuel pump turn on. I even checked the fuel cutoff switch underneath the passenger side, the switch I tested with an OHM meter and tested the electrical connection there as well.

I had not checked the crank sensor or the PATSII.

 

[kevinvug]

Passive Anti Theft

98 Ford explorer will not start with the theft light blinking on the instrument panel. It disables fuel and spark I am told by Ford. I had both of my keys reprogrammed and it still will not start. It is highly unlikely that both of my chips in each key is broken, one is fairly new. The drivers door does not open from the inside, would this have anything to do with the PATSII? Any other suggestions?

 

[gijoecam]

The door is coincidental.

Take us back to the beginning: What happened? Was it working fine one day the not working the next? Who reprogrammed the keys and how?

-Joe

 

[kevinvug]

Ok, long story.

The previous owner, a good friend of mine, bought the vehicle in question brand new in 98. Ran fine until about a year ago when after running it sometimes would not restart. He figured out that if he unplugged the PCM and electrical harness for the fuel injectors and the battery for ten minutes, it would start after that. When I went to go get the vehicle about two months ago, the battery was dead and we charged it for a couple hours. He insisted that it was not going to start. To our amazement, it did. So my wife proceeded to drive it for a month with one incident it not starting and the PCM "trick" worked. Ran fine for another week or so and it would crank but not start. So I started to look at it in our garage and after testing found that there is no fuel and no spark. After my ignition coil tested with little to no resistance using an OHM meter, I replaced it. It still had no spark after that. I did check the inertia swithch and tested the electrical harness and the switch itself and they both checked out fine. As far as I could tell the fuel pump was "whirring" while I tried to start, but after a little investigation from the fuel rail there wasn't any gas that was getting to the motor. I might add that after every attempt to fix, I cranked it at least 10-15 seconds and eventually to the point where the battery was dead.(smart hey? I was pissed)

At this point I decided that it was going to my mechanic.

Off it went and after the first week the diagnosis was the PCM(#1) was bad and needed to be replaced. OK. It was replaced with a used PCM(#2) and reflashed and the keys were reprogrammed. Still wasn't it. Finally someone noticed that the "theft" light was flashing on the dash. My wife had mentioned it, but I thought nothing of it. After the second week my mechanic not only got a code for the fuel pump on OBDII, he also tried to bypass the anti theft, still no avail.

So for whatever reason he also tried to put in the original PCM(#1) and try it that way. ok. didn't work.

Now I have PCM (#1) still in my truck and the "theft" light is still flashing at a medium pace on the dash. It still does not have spark or fuel. It does have compression. My keys have been reset twice now and I'm not sure if the chip in both keys may be the culprit here. At $140.00 I'm not sure. I have heard you can get them on E-bay for $10 and have them programmed.

Is there anyway to just bypass the PATSII permantly? And have the truck still run? Could it be the receiving end of the key in the colum? Is my fuel pump shot? Does BIGFOOT really exist?

It's all a mystery!

 

[Turdle]

I merged the 2 threads on this issue into one, to keep it on track.

And yes-with an excalibrator device and a tune file you can eliminate the PATS system.

Contact James at www.hensonperformance.com

 

[98formulaLS1]

1. there is no way to bypass the PATS completely, without purchasing some other tuning software. The only way to sorta bypass it is to mount the chip onto the receiver on the ignition column.

Did you think that maybe your PATS module is bad?!

 

[gijoecam]

I knew there had to be more to the story!!

It could be the PATS module, or it could be the PATS transciever... either one could cause the PATS to not signal the PCM when cranking, and both would cause no fuel/spark to the engine.

How to test? No clue... the diagnostics are way over my head. The transceiver can be found in a salvage yard, and changing it won't require reprogramming, but there's no guarantees that's your problem.

-Joe

 

[budwich]

I think that you need to back up a bit and start over with your "testing / observations" as there seems to be some "differences in facts".... ie. (original posts indicate fuel was there and then subsequent ones say it isn't, didn't notice flashing theft, now does... medium... don't know what medium is???).

So start over again with your tests.

First thing, is get the vehicle in a "known" state.... I disconnect the battery for 10 minutes to brings things down to "default" in terms of engine operation and hopefully initialize anything else.

Since you think its PATS related, focus your first "test" there.

Check the state of the "theft light"... important, the light should be flashing at once every 2 seconds in "normal mode".

Next, turn your key to run... DO NOT start it, if I understand PATS right (sorry I don't have it on my 96 but my 05 escape does), the theft light should go solid for 3 seconds and go out. Does it???? This is important!!!

IF it goes out then it has recognized a valid key and you can proceed to further testing (dealing with fueling and sparking). IF not, then your issue is related to the PATS and probably more specifically the ignition area / "antenna" and related pickup communicating your key id to the module therein.

Lastly, get a "standard key" (non-PATS) cut to fit your ignition, and try it, observe the system response (key on).

 

[kevinvug]

Sorry for the confusion. Ok. No fuel, no spark... "Theft" light will come on for the solid three seconds and then go out yes... but will still just crank and no start. Otherwise it blinks fast now when the key is not in the ignition.

What is the correct way to test the PATS module?

I contacted James at www.hensonperformance.com, he says for $385.00 I can get a hand held flash unit to permenantly disable the PATS and the truck will still run. Although if that doesn't work if I return it I will only get back $311.06 + the cost of shipping it back to him.

And thank you to everyone who has posted already...

 

[Cobraguy]

Ok
There is a transponder in the key-a receiver in the steering column and a pats ( passive anti theft system) module in the rear driver side cargo area-under the interior panel.

Sorry JT, but I believe that's incorrect. The PATS module is behind the top right side of the instrument panel as best I can remember. The module ou are referring to is the RAP module and is used for remote and keyless entry. You are dead on the money about the receiver. It's next to the ignition tumbler assy.

 

[budwich]

OK... thanks for the "added" clarity. Further question, "blinks fast" still needs more clarification.... time it.... is that "once every 2 seconds" or faster / rapider as in multiple blinks per second. IF it is "once every 2 seconds (key out), then that is normal, if it is more rapid, then it is a good chance that your module(s) (ie. PATS or the transceiver) are not "happy".... as this is a state that shouldn't happen especially after "inputting" a "recognized" key (ie . turned to ON and then turned off and remove).

Further, playing with the PCM / connections is probably not going to do you any good in the long term (and probably already) as those connections may turn into a constant "headache" in terms of "acceptable continuity"....

I suspect that your stuff is OK... it is more likely that you have poor connections along a "few signal paths".... given that "past history" of "disconnecting PCM, then things work for a bit" actions.

PS> Lastly, IF your car was attempted to be started with a "bad key", you need to leave the key (good I think) in the run on position for at least 30 seconds to cause a "timeout" of the anti-theft scanning process. IF this is not done, I think you get your "fast blinking" condition and subsequently NO KEY, good or bad will start your car.

PPS> do you have a factory radio system or aftermarket system???

 

[kevinvug]

To rule them out I checked the following fuses... PCM Memory, Fuel and Anti-Theft System, PCM Diode, PCM Power Relay, Fuel Pump Relay in the Power Distribution Box. And the PCM power diode-Ignition Coils and PATS Module, in the Fuse Panel.

I checked it's factory radio... And yes every two seconds the "theft" light is flashing.

When trying to start the "theft" comes on for three seconds then turns off and does not continue to light up while cranking.

Is there anyway that I can test the PATS module myself or is that a dealer test only?

If I can check it myself, what am I using to test, multimeter? OHM? Voltage? Do I have to buy something to test?

As far as I understand there is no way to test the key but is there a way to test the receiver next to the tumblers?

 

[budwich]

OK... so I would try as I suggested.... put a good key in the "run" position for at least 30 seconds. As mentioned, this will "clear" the "scanning process". Then, you can try a "normal start" process after that... ie. key off, normal 2 second flashing, key on, 3 second solid then off.... try start.

As for your key, just for your own "sanity", get a "non smart key" cut and try it. You should see the theft system activate. You should then be able to "deactivate" with a "good smart key"... observe differences.

As for testing a key, sorry I don't know... I think normally people just reprogram them which is basically the test for them to work.

As for the PATS testing, I think your are "stuck"... having said that, the tests that I have suggested are the basic tests to check things out.

I don't think its a PATS problem.... I suspect you need to check your connection with regards to your PCM... grounds, and batteries. To me your PATS system is doing "good" and appears to be causing the appropriate response (extinguishing theft light) when it should ... which indicates that it is detecting a valid key and is communicating with the PCM.... its from there that your problem exists... my opinion.

 

[kevinvug]

Alright

 

[CDW6212R]

It sounds like you should be close to finding the problem. My 98 had a starting issue occasionally that went away finally. I think that my issue was likely the ignition key reader, either not pulling the key code or not transmitting it to the PATS correctly.

If the PATS system does not recognize a key when the ignition is turned on, the "THEFT" light will flash continuously. The fuel pump will trigger momentarily with or without a good key. If the key code is verified, the pump will run for over a second. If the key is not recognized, the pump will briefly run, and be disabled before the normal priming period is over.

Watch the theft light carefully. If it ever flashes when the ignition is just turned on, do not try to start the engine, that will be a waste of time. When the theft light flashes(ignition on), then PATS has disabled the ignition and fuel.

The PCM and PATS module are married, you cannot swap either of them without dealer reprogramming.

When you do get it running again, try to be able to check the fuel pressure. The intermittent symptom sounds like the CMP or a key code problem. Regards,