joecrna
Well-Known Member
- Joined
- October 25, 2006
- Messages
- 735
- Reaction score
- 2
- City, State
- Las Flores, CA
- Year, Model & Trim Level
- 98 XLT 4X4 sohc
OK, first lets assume that your new alternator is designed for a Ford (they are differnet than GM etc). Second, it is for the correct model year (again, they vary). Specifically the first two are differences in how the regulators work. Now tell me what you mean by FLD. If this is the feedback for the regulator (and thats how your model year of Ford was designed from the factory) you have answered your own question. Remember, modern electrical systems are different and more sensative than older ones. The light bulb/warning circuit doesn't care what the voltage is but the computers do. If the field wire puts out a differnt voltage than stock they see it as a failed alternator or regulator. Im surprised you don't have a check engine light too. Probably a stored code somewhere. I agree 15.1 volts isn't likely to cause a problem but 3.5-4.5 volts is a problem.
Check what the stock alternator put out on that little extra wire. Trace where it went, I think clear back to the fuse block under the dash and to at least two computers ( one is the GEM) and then back to the regulator. Fix this and your light goes away. I am no expert on your exact year of Ford but that is how my charging system worked when I was installing a battery isolator and heavy gauge wiring so I could charge batteries on a trailer and trying to allow the trailer charging system to send power foreward to charge the truck if needed.
Check what the stock alternator put out on that little extra wire. Trace where it went, I think clear back to the fuse block under the dash and to at least two computers ( one is the GEM) and then back to the regulator. Fix this and your light goes away. I am no expert on your exact year of Ford but that is how my charging system worked when I was installing a battery isolator and heavy gauge wiring so I could charge batteries on a trailer and trying to allow the trailer charging system to send power foreward to charge the truck if needed.
