Resolved PATS problem with a Mustang 2010 V6 - SOLVED-

[MRMRacing]

-EDIT, PROBLEM SOLVED - Last summer I bought a V6-2010 to my daughter. Did som upgrades before christmas (lighting, paint bumpers etc). Drove the car a few times in and out of the garage.
Then it was sitting for a month with no batteries in the keys. One day it would not start and PATS flashing. All fuses checked twice, did a scan and PATS enabled no keys found. Did buy forscan and it said "erased both keys and no new key found". Tried many times still same fault no key found. I tested 12 volt and ground to the transceiver. Bought a used key set and ignition lock with transceiver. Tested with the new transceiver installed (same part number) but none of my now three keys where found. Then I tried with the transceiver connected but on the side with the new key stuck into that and it succeeded to program one key. But the car will not start with one key only. Tried multiply times again but right now Im at zero keys again. I have not removed the IPC to check the two can wires to that but seems like a forscan problem? Taking the car to a Ford dealer with other software needs a tow truck. Any help are welcome

 

[MRMRacing]

I did some testing with my scope and I got the 3 sec toggling to request on the transceiver and it sends signal back. But cant find my two keys. Strange that both old keys stopped working? I have ordered a new pair from amazon to test.

 

[Noobz347]

I will preface this post by saying, I know dick about PATS and how it works.

This may help provide some clues?

Chat GTP Response:


If your 2010 Mustang V6 is not recognizing either transponder key and FORScan is unable to detect them, the issue is likely related to the Passive Anti-Theft System (PATS) or a problem in the communication pathway between the PATS module, PCM, and key transponders.

Potential Causes and Troubleshooting Steps​

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1. Check for PATS System Fault Codes​

Before diagnosing deeper, check FORScan DTCs under:

• PCM (Powertrain Control Module)
• ICM (Instrument Cluster Module, which houses the PATS)
• PATS-related modules

If no communication with the keys is happening, look for codes such as:

• B1600-B1602 – Key transponder issues
• B1213 – Too few keys programmed (less than two)
• B2103/B2104 – Antenna ring (transceiver) issues
• U1900 – Network communication failure between modules

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2. Check the PATS Transceiver (Antenna Ring)​

• The PATS transceiver (antenna ring) sits around the ignition cylinder and reads the key’s transponder chip.
• If it's damaged or unplugged, the car won’t recognize any key.
• Steps to Check:
  1. Remove the plastic steering column cover.
  2. Inspect the transceiver ring and wiring harness connection.
  3. Try unplugging and reseating the connector.
  4. If possible, test with a new or known working transceiver.

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3. Check for PCM to PATS Communication Issues​

• If FORScan cannot detect keys, the ICM or PCM may not be communicating with the PATS system.
• Possible Issues:
  • Corroded/loose PCM ground or power connections
  • Failed CAN bus communication between modules
  • Blown fuse for the PATS circuit

Steps to Check:

1. Inspect PCM fuses in the under-hood fuse box.
   • Check Fuse #27 (7.5A) (PCM Power)
   • Check Fuse #34 (15A) (Ignition/PATS)
   • Replace any blown fuses.
2. Check CAN bus wiring between PCM and PATS module.
3. Perform a battery disconnect reset:
   • Disconnect battery for 15 minutes.
   • Reconnect and try again.

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4. Try a PATS Reset/Relearn with FORScan​

If the keys are not being detected but no hardware issues are found, try a PATS reset or key relearn:

1. Go to the PATS menu in FORScan.
2. Perform a PATS reset.
3. Try adding both keys back using the key programming function.
4. If the PATS system is locked, you may need to wait 15 minutes for it to reset.

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5. Faulty Keys or Erased PATS Memory​

• If someone previously erased the PATS memory, the ECU won’t recognize any keys.
• If both keys fail, it’s possible they were deleted or lost synchronization.
• A locksmith or dealer may be required to program new keys.

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Final Thoughts​

Start with checking for DTCs in FORScan
Inspect the PATS transceiver around the ignition cylinder
Verify PCM/PATS module communication and fuses
Try a PATS reset and reprogramming via FORScan

If no communication is detected, the PATS transceiver, PCM, or wiring is likely faulty. Let me know what DTCs you find, and I’ll guide you through the next steps!

 

[Noobz347]

I didn't get too much additional info from Grok 3 except this:


Stuck in Anti-Theft Mode: Sometimes, after a battery drop or prolonged inactivity, the PATS system locks into a security mode and won’t recognize keys until reset. Try this: insert a key, turn it to the "on" position (not start) for 10 seconds, then off, and repeat with the second key. It’s a long shot, but it might jog the system. Forscan might also show a “theft” status or code if this is the case.

 

[MRMRacing]

Thanks, for posting this, I have tested with a new transceiver with same result. I had two keys when I bought the car, but have only used one and do not know if the other was working. I did run forScan erase and program keys. Two keys was found and erased. No new was found. So now I has 0 keys programmed. I bought a used key with transceiver and forScan did find that key but will not run with only one key programmed. So I'm waiting for new keys to arrive and try program that. If so my old key went bad and caused the problem. I did scope both request from ICM to transceiver and the respons back to ICM that looked okay. I did scan DTC and has only PCM error due to Theft-alarm and to few keys programmed. So will wait for new keys and try

 

[MRMRacing]

Went to a US Ford workshop in Stockholm and bought a genuine Ford key (expensive). And tried program that with forscan and worked directly! So I went back today with my old key and he did copy that to the new (grinding). He told me that if I buy a pirate key it should be labeled S at the blade? Anyway both my non Fordkeys where problematic and stopped working for some reason

 

[Noobz347]

Went to a US Ford workshop in Stockholm and bought a genuine Ford key (expensive). And tried program that with forscan and worked directly! So I went back today with my old key and he did copy that to the new (grinding). He told me that if I buy a pirate key it should be labeled S at the blade? Anyway both my non Fordkeys where problematic and stopped working for some reason

That's good info for others.

El-Cheapo clones are garbage and may not work at all.

 

[MRMRacing]

I checked and the used key that I bought and the new original Ford key had SA stamped on the blade. So it is possible that the two needed keys has to have this stamped? May be the "pirate" non SA key can be programmed as spare keys when two SA already are programmed?