Won't start and anti-theft light flashing

Discussion in '2005+ Mustang GT 4.6L Tech' started by Jcode68, Apr 6, 2020.

  1. Jcode68

    Jcode68 How I Roll

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    I have a 2007 GT and have experienced the following problem last summer/early fall when the weather was still hot. I drive the car home from work, about a 50 minute drive and the outdoor temps were pretty hot, about 91 degrees. I get home, shut the car off and go in the house. Come out 5 minutes later and the car won't start, not even a click. My battery is recent and has full charge, lights and stereo work etc. when this happens, I notice the anti-theft light flashing on the dash when I put the key in the on position. I have tried multiple times to repeatedly unlock the car, lock, unlock etc and makes no difference. I tried my spare key, fiddled with the key, banged a little on the steering column thinking possible loose connection to no avail. I read some posts about the module in the steering column going bad and unable to recognize the keys. The thing is, both times this happened, I let the car sit for about an hour and tried again and started right up.
    I decided to have the local Ford dealer diagnose the problem. They were able to reproduce the issue after running the car for about an hour, seems to be induced by temp. They said the PCM is overheating due to a faulty circuit in the PCM. They quoted me $1200 for the replacement of the PCM, part was about $750, the rest is labor to replace and diagnostics. Freaking sucks since the car has only 34k miles on it, but I have no choice as I can't drive a car with that kind of reliability problem. Anyone else experience a problem like this with the PCM?
    I am running a Steeda cold air kit and BAMA tunes, using the 93 Race tune. Wondering if the tune could be adding to/creating the problem? I ran the same tune the prior couple of years without issue, but I do notice the fan runs quite a lot with this tune compared to stock (expected but comes on very soon after startup before engine is warmed). Appreciate any input and thoughts from the group before I throw a good chunk of change to replace a very low mileage PCM with a refurb that likely has many more miles.
     
  2. Macman45

    Macman45 Resident Geriatric

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    I think it could also be a faulty SJB, unsure where the antitheft is stored, ECU or SJB. It's one of those that's faulty
     
  3. Jcode68

    Jcode68 How I Roll

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    I think the anti-theft is ECU, but will do some research on the SJB. I also just came across this video done by a Ford mechanic. Granted this is on a newer Focus, the symptoms are the same. I am going to cleanup the ground connection as he suggests and see what happens before spending the $$ on replacing the ECU. Any other thoughts or validation this could be the culprit?
     
  4. RavenGT

    RavenGT Junior Member

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    PATS keys are programmed to the IPC (Instrument Panel Cluster).
     
  5. Macman45

    Macman45 Resident Geriatric

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    Hmm I dont know about that, you can hot swap clusters in these cars and they start. Key doesn't seem to follow the cluster. May relay info from the ECU
     
  6. RavenGT

    RavenGT Junior Member

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    You could be right. However, the 11-14 cars definitely store the PATS codes in the IPC. The 99-04 cars were the same way. Quite possible the 05-09 (10?) cars are different. Worth looking into anyway.
     
  7. Jcode68

    Jcode68 How I Roll

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    Giving this a bump in hopes someone has other suggestions before I pull the trigger and replace the ECU.
     
  8. Juice

    Juice forum member

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    Not on an 07. PATS is in the pcm IIRC.
    I would be looking at the sensor ring around the ignition switch. Read codes on pcm and post them

    The Coyote cars have the PATS module in the cluster.
     
  9. Juice

    Juice forum member

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    I doubt a pcm would fix the issue. Pcm dont go bad very often.
     
  10. RavenGT

    RavenGT Junior Member

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    FWIW, the 10 cars also have the PATS codes in the IPC and they are of course 3Vs.
     
  11. Juice

    Juice forum member

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    Yea, not too up on the 2010s.
     
  12. Jcode68

    Jcode68 How I Roll

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    Thanks Juice. I came across a video on YouTube of a Ford mechanic who troubleshot the same symptom on a Ford Focus to a bad ground. I am going to check into this as a target, but the problem only occurs when temps are hot. Wondering if when the temps rise, the a poorly grounded circuit becomes more symptomatic. Any thoughts on this theory? Car only has 32k miles and is garage kept. Am surprised Ford mechanic said the PCM was the problem. Unfortunately/fortunately doesn't seem to be a common problem so little info out there for me to go on.
     
  13. Juice

    Juice forum member

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    Is certainly a possibility. With all the computers communicating with each other, grounds become very important. Metal expands with heat, it could happen. Computers want clean and consistent power or they get very confused.
     
  14. Juice

    Juice forum member

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    Its all coming back to me know, lol.
    Here is the breakdown on 07-09 PATS.
    Pcm and pats module are both in the PCM. PATS does NOT use the can bus.
    The sensor ring around the switch has 4 wires. +12v, ground, and tx and rx wires. These run directly to the pcm.

    A fault code should be able to tell you if the no start is from not seeing the chip key OR sensor ring fault.
    Clear as mud?
     
  15. Jcode68

    Jcode68 How I Roll

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    Yes, clear as mud ;-) My understanding with the potential grounding issue is that when this occurs it essentially is breaking the ability for the sensor ring to communicate with the PCM, creating a no start condition. All other electrical aspects of the car function (radio, windows, locks etc). I am going to look at the ground and use sandpaper to remove any paint and corrosion that could be impacting and see if the problem still happens. The weather is still cool here (50 degrees) so not sure I would be able to repro the issue yet to know for sure. Thanks for the input!
     
  16. Juice

    Juice forum member

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    Dont forget there is circuitry in the sensor ring. Its not uncommon for a failing integrated circuit to work cold and stop working after it heats up.
     
    Jcode68 likes this.
  17. steve arizona

    steve arizona Junior Member

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    ive had this exact issue with mine starting in february,,(i live in the desert (arizona)so not sure if heat an issue) found resetting the alarm (usually numerous times) gets it to start but is fustrating as only a weekend driver so every friday im doing this, the rest of the weekend its fine. have been starting car every evening past week and it starts every time, so far,,mine has 114k miles so may be age thing as opposed to miles. i watched the above refrenced video on the focus so will try that too,,,
     
    Jcode68 likes this.
  18. Jcode68

    Jcode68 How I Roll

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    I spent some time inspecting things yesterday and have a few thoughts for feedback:
    1. I did a visual inspection of all wiring and connectors in the engine bay. My car is a Cervini build C300 which includes the PIAA lights in the front end. When they installed them, they covered the wire running into the passenger compartment to the switch in plastic loom (this is good). The wire runs the passenger side fender well inside the engine bay and wire tied to the factory harness bundle. The plastic loom was very melted for about 8" of length where is lined up with the exhaust manifold. It is as far away as it can be and none of the factory wiring loom or wires seem to be effected. The wire itself is not melted and seems to be in good condition. This to me is a red flag.
    2. I disconnected and removed the PCM for a bench inspection and close look at all wired and connectors, everything still looks like new and could see no signs of problem. Doesn't mean much since could be a failure within the PCM as the Ford tech suggested.
    3. None of the ground wires/connectors appeared to be oxidized, but I removed the ones I could find, wire brushed them and sanded the paint off the connection point to ensure good contact.
    4. As I mentioned before, I am running a BAMA "93 race tune" and "think" I started running it in the fall of 2018. So I ran with all of last year and started seeing this problem when the weather got hot. I recall when I first started running this tune, I noticed the fan was running all the time and almost right after startup. I assumed they programmed it this way, my coolant temps did run a bit hotter but never what I would consider a problem zone and never triggered an overheat condition. That said, given how hot the exhaust manifold is getting, it would suggest the timing for this tune may be too far advanced.
    5. Does the Ford PCM have an internal safety to shutdown or disallow startup if temp is too high? When the problem has happened, I shut the car off for maybe 5 or 6 minutes while I went into the store and during that time the fan is no longer blowing/cooling. I'm thinking this has now caused everything under hood to heat soak.
    6. Last thought I had as I was inspecting things is that the car is now 13 years young, low miles and garage kept. However, I have never changed the coolant and am thinking it has likely lost some/most of its cooling effect.
    So before I replace the PCM (suggested by Ford tech) I am going to load the BAMA 89 octane tune, drain and replace the coolant with fresh and replace the melted wire loom I found. I am going to run it like this for a while to see if the problem surfaces again. If it does, I plan to replace the PCM. If not, I will be contacting BAMA to let them know about it and to check the tune they provide me. I might just do this now anyway to see what they say. Appreciate any thoughts and feedback.
     
  19. Juice

    Juice forum member

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    Can you restore to stock and try that?
    As for having a safety built into the pcm for preventing startup, I cannot answer. But, if you leave the key on when it wont start, and.let the temp guage reach whatever temp the engine is could give you an idea of what temp the pcm thinks the engine is at.

    Exhaust that gets too hot is usually from a lean condition, not timing, if it is even getting too hot. No way to know.

    Good luck with bama support. I forsee some colorful language in you future.....
     
  20. Jcode68

    Jcode68 How I Roll

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    Thanks Juice. I can return to stock, but think I will just go back to running the performance 89 tune. I ran that tune for several years prior without any issues, so will see if that makes a difference. Yes, I should have thought about it more before posting, but you are right that indicates a lean condition. I have been reading through several posts about BAMA race tunes and haven't seen any similar symptoms yet, but some comments about lean conditions in the upper RPM range.
     
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