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96 GT PATS theft light flashing, car starts and dies

4600 Views 1 Reply 2 Participants Last post by  lefty310
So after work today out of the blue for no rym or reason my car starts and dies instantly with the THEFT light flashing, and then just cranks endlessly without starting.

Nothing on the car has been changed or altered in the last few days, and the car does the same thing whether i start it with the chipped key, or the solid unchipped one i had made for unlocking and just in case.

Called ford dealer and they said the key had likely died, and they offered to tow the car in for a fee and fix the problem for a lot of cash.

No Computer codes that my tuner could see but made aI discovery after 20 minutes of jacking with the car, i discovered a few things.

Im a network engineer and i know the keys emit a signal so i began tinkering under the assumption the signal was either being jammed or there was some kind of interference.

Turned off my phone, radio, my dash mounted tablet, no difference.

Tried starting with my metal key while holding the chip key against the base of the lock cylinder, and got a start for a few seconds then it died. But it stayed running for like 5 seconds almost indicating it was working for a second with the key closer to the sensor.

With that i continued looking for anything that could cause interference.

I tried a start after checking the codes again with my SCT tuner still connected to the OBD2 socket and magically the car started and ran fine. I know the SCT tuner being plugged in or not should mean jack **** towards starting the car so i kept trying to figure it out, and then figured out it wasnt plugging in the SCT which fixed the problem, it was the removal of my Bluetooth OBD2 dongle which actually allowed the car to start. Plugging the dongle back in essentially was jamming out the PATS sensor from reading the keys signal.

I used a cabling toner against the Bluetooth OBD2 dongle with it plugged in and got a lot of static off it which i know is strange so i removed it and the car runs fine ever since i did. The OBD2 socket looks undamaged, and i tested changing tunes with the tuner and that works fine as well.

I cracked open the dongle to find that the inside of its housing was severely melted and the circuit board was burned. Upon further looking with a magnifying glass it appears the Diode that feeds the circuit with power supply voltage got so hot it melted everything around it, and shorted some solder points to the Bluetooth transmitter module next to it. My guess is those shorts caused the Bluetooth Transmitter to erroneously transmit essentially a jamming signal which blocked the chip keys own signal.

With the dongle powered the key can only barely intermittently be seen by PATS even if its held to the very closest point to the sensor. Ill be buying a new dongle now.

I posted this in case anyone encounters a simular problem so they dont go thinking PATS has died or simular.

The Bluetooth Dongle i had in use was the Following:
Vgate Bluetooth ODB2 dongle

Ive had this dongle for 2 and a half years, this is the first time ive had a single issue with it, so it may just be age killed the diode causing it to heat up and kill the device.

It is the one shown in this video at 1:20:
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The power of knowledge. Congratulations and good job on posting this for the potential benefits of others.
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