How the Ford PATS antitheft system works
Ford PATS overview
Ford PATS Passive Antitheft System uses a key with a transponder in the head of the key. Each transponder is coded with a unique identifying code made from a possible 18 billion combinations. It’s a passive system because it doesn’t require any input from the driver. Ford has also referred to their PATS system as SecuriLock.
The second portion of the system is a PATS
transceiver module. The PATS module communicates Generates an “exciter” field that powers the chip in the key, which then transmits encoded data back to the transceiver. The key contains a spool of wire that converts the “field” to power to run the chip, so the key never needs battery replacement. The transceiver then communicates with the PATS module.
Where is the PATS module?
Over the years, Ford has located the PATS module in different places;
• In some vehicles, it’s built into the instrument cluster
• On some models it’s a separate module.
• On some late model vehicles, the PATS module is located behind the steering column shroud and contains an antenna connected to a small electronics module.
As you turn the key to the RUN or START position, the PATS control module initiates the key interrogation routine. The PATS transceiver is mounted on the ignition lock cylinder housing and is connected to the PATS control module. The transceiver energizes the transponder key electronics through the key’s circular antenna. The PATS transceiver receives data from the control module through the transmit Tx signal. The transceiver sends the key code to the control module through the receive Rx signal.
The key code data is stored in the PATS control module. The PATS control module compares the received key code and validates or rejects the key code. If the key code is correct, the PATS control module sends a signal to the PCM to enable the fuel pump and injectors.
During this period, the PATS security warning light is illuminated. If the key code does not prove out or there is a fault with the system, the PATS warning light will either stay light or flash.
These faults will disable the vehicle from starting
• incorrectly encoded ignition key
• damaged encoded ignition key
• unprogrammed key
• non-encoded key (key has no electronics)
• damaged wiring
• damaged transceiver
• damaged PCM
Like any electronic system, Ford has gone through several variations on the PATS system. There are five variations of PATS in use on Ford vehicles. Systems are identified as types A, B, C, D, E, F and G .
PATS System A
The PATS control is a stand alone module. When you turn the key to RUN/START, the theft warning light turns on for 2-seconds. Only 1 key needs to be programmed for the system to work. Up to 16 keys can be programmed.
The transceiver sends the key code signal via a hardwired connection to the control module.
At each start sequence, the PCM power the fuel pump and injectors until the engine runs for 1 second. Within that 1 second period, the PATS Control Module must determines if the key code is valid. If it is, the control module sends a validation signal to the PCM via the Vehicle Communication Network (SCP). The PCM then allow the fuel pump and injectors.
Some vehicles also include a starter relay. If the key code is valid, the PATS control module also grounds the control coil in the starter relay, which moves the contacts and sends power to the starter motor solenoid
PATS System B
Same as System A but:
Must have two programmed keys in the control module to allow vehicle starting. Only accepts 8 programmed keys.
PATS System C
Same as System B but:
The PATS control module is NOT a standalone module. It is built into the instrument cluster.
PATS System D
Same as System A but:
The PATS control module is a standalone module located behind the dash on the left side.
PATS System E
Same as System A but:
The PATS control module built into the PCM.
The PATS control module in the PCM provides ground to the starter relay and enables the fuel pump and injectors.
PATS activation signs
The PATS system isn’t working properly if:
You see a rapidly flashing theft indicator with ignition on
Start and stall, within 1 second
Cranks but won’t start
These are NOT symptoms of a PATS problem
If the vehicle runs for more than 1 second, then stalls, it is not a PATS issue.
PATS cannot cause a running vehicle to stall.
Alarm goes off – PATS is completely independent from the perimeter alarm system.
Remote Keyless Entry – PATS is completely independent from the RKE system.
No-crank on a PTS vehicle without starter disable. Check the vehicle list for the presence of starter interrupt.
WARNING: Items such as foil stickers, brass key tags, other PATS keys, other
transponders used to purchase gasoline or other metallic objects can cause
interference with the PATS key.
Erasing and reprogramming ignition keys does not cure any known
intermittent PATS no-start issues. Do not reprogram keys if a fault cannot be
identified. Reprogramming the PCM does not have any impact on PATS operation.
Repairing a PATS system
Every day in every auto forum I see people asking how to bypass a Ford PATS system. I just shake my head because fixing a PATS system is NOT difficult and you’ll probably spend more on a bypass kit than it’ll cost to just fix it properly. There are only two parts to the system as shown above: transceiver and control module. A new transceiver costs about $50. If your control module is bad, you can buy a new one from Ford for about $175 or buy a rebuild unit for about $40. Yes, you’ll have to pay a shop to program but you’ve got a full fix for maybe $250 all in and you don’t have to jury rig it.
Start by reading the PATS trouble codes
Most of the PATS trouble codes are body “B” or data “U” type codes. You must have a code reader that can read these codes. Repairing a PATS system is NOT hard.
B1213 Less than 2 (or 3 if equipped w/Valet key) keys programmed to the system.
B1232/B2103 Transceiver internal antenna damaged. Replace transceiver.
B1342 ECU is defective (EEPROM in PCM is not working — replace PCM). PATS related when stored in PCM only.
B1600 Non-PATS Key or damaged key.
B1601 Unprogrammed encoded ignition key detected (leave ignition on for 20 seconds before trying a programmed key, in Anti-Scan Mode).
B1602 Partial detection of encoded ignition key.
B1681 Transceiver signal not detected.
B2141 Non-Volatile Memory (NVM) configuration failure — No PCM ID stored in PATS.
B2139/U2510 PCM ID does not match between the PCM and PATS control
B2431 Key program failure (defective key or transceiver).
U1147/U1262 Communications issue, SCP (J1850), between PCM and PATS control (PATS/ICM/VIC/HEC/SCIL).
U1900/U0100 Communications issue, CAN (J2284), between PCM and PATS control (ICM).
U2511/B2009/P1260 PCM disabled the vehicle because of a PATS concern. Retrieve DTCs from applicable PATS control function (PATS/ICM/VIC/HEC/SCIL).
I get lots of requests for instruction on how to do a PATS Bypass. Let’s get right to the point; if you have a problem with the transceiver or key, it’s easier and cheaper to replace those parts than to pursue a PATS bypass. Yes, you might need some reprogramming, but most shops and auto locksmiths can do that kind of work these days.
The real problem come in when the PATS module has failed and you can’t find replacement parts. Then you have two options.
• Send the PATS module in to a rebuilder
• Pay a company to perform a PATS delete. In that case you most likely have to send your PCM into the company to have them alter the software so it no longer looks for a PATS signal.
If that’s what you’re looking for, contact ECUConnection.com.
©, 2018 Rick Muscoplat
Posted on by Rick Muscoplat
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