Battery Light Intermittent On/Off

[dhanni848]

Yeah not sure either, but it was a running joke at the store every time I walked in. They say "oh you're the guy with the Raptor".

 

[W0n70n]

Yeah not sure either, but it was a running joke at the store every time I walked in. They say "oh you're the guy with the Raptor".

Yeah, they still haven't forgotten about me at the store. My OEM alternator unscrewed the pulley and shredded the belt so I drifted the powersteering-less truck to the front of an o'reilley and ripped the alternator out in front of their store (which involves removing the supercharger compressor). I got it all installed and it was all fine for 24 hours then battery light and that god forsaken beeping warning signal that I have nightmares about. The parts store guys were really good sports about it all since they knew it wasn't my fault and took back their alt after my mechman came in the mail a week or so later.

 

[The Car Stereo Company]

i believe there is a reset procedure for the bms? that might be your issue. @FordTechOne or @Spectragod might know more about it

 

[W0n70n]

i believe there is a reset procedure for the bms? that might be your issue. @FordTechOne or @Spectragod might know more about it

There is, it involves making sure the truck is off and fully asleep (no key fobs nearby or doing anything with the truck) for 8 hours and the system will read the new charge level on the new battery, I think it can also be reset through Forscan but I can't remember right now. The issue is that no amount of messing with the PCM will make a generic autoparts store alternator work in our trucks, I don't know if it's a tolerance issue or a small difference in parameters between SVT and regular f-150s or what but I tried 3 "new" parts store alternators and none of them, new and tested out of the box, worked for more than a few hours. Swapped in a new Mechman alternator and it instantly worked perfect and no complaints since.

 

[FordTechOne]

i believe there is a reset procedure for the bms? that might be your issue. @FordTechOne or @Spectragod might know more about it

There is a BMS reset procedure available in IDS. Alternatively, allowing the vehicle to sit for 8 hours in disturbed (no doors open or key fob commands) will allow the system to re-learn the battery state of charge on its own. The BMS has nothing to with charging; it’s purpose is to monitor battery state of charge to prevent a discharged battery with the engine off. If the BMS detects slow state of charge, the load shedding strategy will activate and you may see a “system off to save battery” message.

The reason there are issues with aftermarket alternators is due to the voltage regulator. The PCM communicates with the regulator over the GENMON and GENCOM circuits. The aftermarket regulators are often not built with the same tolerances as the Ford regulators, which causes the PCM to set a DTC.

 

[dhanni848]

Yes to all are dying. Voltage regulators were the problem in all the bad ones I received. No issues since. I did the reset every time.