Intermittent PATS (passive anti theft) problem

[spork]

This is kinda long. Sorry 'bout that.

HISTORY:

I was cruising along about 45mph and the entire truck went dead. I coasted off to a side road, but the truck was still in a rather precarious position (with 5 o clock traffic rapidly approaching).

The battery was fine... it would crank all day, but no start. The PATS "theft" light was flashing rapidly (after the 3 second prove-out). The odometer display changes from "current mileage" to "--------". Being stuck in a bad intersection with traffic building, no method to google "what's wrong" ... I opted to tow it to a shop and get it out of the way. Normally, I'd tinker with it and take a stab at figuring out what is wrong.


That was a couple of days ago. I've had a chance to google around and the mechanic has had his first look at it. His analysis is there is a screwup with PATS (I figured) and the instrument cluster will have to be yanked and sent off to Ford for repair/replacement/reprogramming. He tells me it starts fine in the morning (cold) and will go back to PATS lockout if parked in the sun.

My internet searching tells me this is a "type C" PATS... and that there possibly may be a flashing code of the theft light. I tried to ask the mechanic what code it was flashing, but he kept thinking I was asking about the OBD code -- and I couldn't steer him back to the flashing code of the theft light. (Incidentally, the OBD code is "problem with PATS". Thanks, Ford. Helpful.)

Supposedly the type C PATS does lie inside the instrument cluster. My previous experience with the cluster is that there are known cold solders on the board. My odometer display has been flaky for years -- working off and on. About 3 years ago I stumbled on a fix, pulled the cluster and resoldered the cold connection. It has worked fine since. However, this does lead me to think there may be more bad solders on the board that could be causing this issue. Reading Ford documents on PATS, I see that it is "impossible" for PATS to engage after the engine is running. Again, this leads me to think there's a bad connection somewhere. Again suspicious of the cluster.


QUESTIONS:

1. Does anyone have experience with this type of intermittent PATS failure? If so, was there any fix short of sending stuff off to Ford?

2. Assuming I can get PATS working... is there any hack to disable PATS entirely? The "fixes" I have seen involved gluing one of the approved RFID chips to the receiver -- and I don't see that as a fix at all. I'd just rather the system be gone entirely.

 

[corlon]

does the vehicle have any aftermarket electronics in it? remote starter or something else that is interfaced in the key security system?

 

[spork]

No, not a one. No starter. No alarm.... Even the radio is factory.

 

[corlon]

well from putting a lot of remote starters in these vehicles i can tell you that the pats system only cares about seeing the key @ startup. if you take the key out while its running (remote started) the vehicle will stay running. i've seen the pats system get upset when its two data wires touch each other though. perhaps the ring on the key cylinder is bad. wierd that no one else has had this issue. have you looked on the f150 forums yet?

 

[spork]

Yeah, I've read several official looking Ford documents stating it is impossible for PATS to interrupt the engine once it starts... though... having sat in the seat when the engine died and complained of PATS... I'm thinking that it was designed to be impossible... and actual implementation may vary.

I've found one other extremely similar case on another forum. That guy ended up replacing (and reprogramming) the instrument cluster (which didn't fix it) and then replaced the main computer. That fixed it... though hard to say if it was just the computer or the combo.

 

[drtj]

had any luck with getting it fixed? Im kinda in the same boat. sometimes the odo will work sometimes it wont. The other day i couldnt get it to start. the theft light was blinking fast waited 5-10 minutes with key out of the ignition & it started. its been sitting in the yard since then. going to look at it this weekend. If you got it fixed id like to know what it was so i can start there first.

 

[spork]

Short answer: yes. All fixed.

Long answer: it seems that there is a wide variation of how this works based on year of vehicle. Your mileage may vary!

On my vehicle (according to mechanic that fixed it) the PATS is located inside the speedo. The procedure was (in my case): buy new speedo, take both the new/old speedo and the truck to Ford and have them transfer the data from the new to the old. Oddly, the transfer procedure cost me more than the new speedo.

The new speedo fixes both issues (for now). It fixes the PATS and the odometer problem.... though the odo is a different thing entirely (which is user repairable if you have a soldering iron and a little patience).

 

[stoplight]

Mine is a 98 5.4L 4x4. While driving the engine will stutter momentarily and then regain power...at its worst the engine will shut off completely...not so great if on the freeway but will start back up again. Our guy has tracked it down to the ECM...first he thought it was the GEM but found nothing wrong, pulled the ECM and had it tested and it shows bad. Should get it back shortly has he is having problems finding an ECM with the YC code.

But that said first I have heard of the fix you describe...have never had a problem with the dash..knock on wood...

 

[drtj]

well the dealer just called me. he said it was a bad PCM relay or a ECM relay. it was one of the 2. Total cost was $185. Thats A LOT cheaper than what i was expecting

 

[PO'dexpd'nowner]

well the dealer just called me. he said it was a bad PCM relay or a ECM relay. it was one of the 2. Total cost was $185. Thats A LOT cheaper than what i was expecting

Could you tell me where the PCM relay was located? Correct me if I'm wrong but you really can't test a relay can you? Just replace and hope it works?

 

[Captain Morgan]

A relay has 2 connections that pwr it and 2 or more connections for the circuits they switch. In order to test it more than putting a voltmeter across it you would have to keep it powered and see if it falls out and fails to stay powered. How are you going to do this in a real world scenario with vibration and heat etc? For how long?

Old relays have tarnished, oxidized or corroded lugs and the electrical connection to the pwr or the circuit it switched be intermittent. (only needs to be a fraction of a second in some cases to freak out the brains)

Replacing the relays assures that you can put in a relay that has a clean burnished surface and hasn't been subjected to years of heat and use, but if the socket it plugs in to is also tarnished and oxidized it may still not have a sound and reliable electrical and mechanical connection. If it were me, I would use a tiny flat file to score the female socket where I plug the relay in to.

Relays are cheap whether they are old school or completely electronic and you can swap these out yourself.

I found THIS as a PCM-relay-getting-voltage-diagnostic test on another forum.

For less then the cost of the repairs you are mentioning, you could swap ALL of the relays and fuses.

 

[ELVATO]

For what it's worth, the solution to the problem in the link you posted from the ford-truck site is to replace the fuse box. The early 03's had an issue with the fuse box (CJB) circuitry that would fry PCM relays. There's a thread about it on the site.

Heh, at least our PCM relays are a whole lot cheaper since they're the generic skinny ones.