I have a 1999 Ranger 3.0 L. Just curious if this would cause keys to not program. The dealership has had my ranger for a week and that’s what they came up with.

No, not the BCM, aka GEM

PATS module above glove box and the PCM(powertrain control module/engine computer), are needed to add/save new PATS keys to the anti-theft system

PATS(passive anti-theft system) was added to V6 Rangers in 1999, 1999 and 2000 Ranger used a separate PATS module to read transponder key numbers and then give the PCM a "go" or "no go" for engine startup
In 2001 to 2003 Ranger the PCM had PATS software inside, so no external module needed

There is another part of the system, called the transceiver, its just a powered antenna that loops around the ignition Key slot, it allows PATS to read the key's "number", but wouldn't be needed to program keys using a laptop with Ford software


But in fairness to mechanic, BCM is a pretty generic term to tell a customer, vs PATS module and PCM, so alphabet soup terms, lol
Way easier to explain its a "body control" system issue, than details on how PATS works

It wouldn’t start and anti theft light would blink fast. I pulled the floor cover off and saw the transceiver duct taped with an old key inside. I reinstalled the transceiver where it goes around the key port. Took it in to get the new key programmed. That’s when they said the bcm not pcm. Emphasis on the “not pcm”. Though I thought it would be a bad pcm.

Reads like someone changed the ignition cylinder and didn't want to match keys, lol
But the key you were using should NOT have been a transponder key, unless the transceiver was located away from ignition switch with old key taped in it
Because if you have two PATS keys close to the transceiver and turn on the key then BOTH keys sends out their code at the same time so PATS module doesn't get a good number, its garbled

Anyway, yes thats classic description of PATS being activated, rapid flashing theft light, it will flash a code number after 45-60 seconds, 11 to 16, telling you what the problem is
The PATS codes set ARE "body" codes, starts with B, like engine codes start with P(powertrain)

Here are the PATS B codes
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(PATS/ICM/VIC/HEC/SCIL).
B2431 Key program failure (defective key or transceiver).



1999 Ranger PATS wiring diagram below, no mention of BCM
2000 Ranger was the same