Originally Posted by mikeeshaq
Where are you getting that F601 voltage regulator from? Just a name then I can search for details.
I'm getting the F600 style. The F601 style is what they have stock, these require the signal from the PCM where the F600 does not. You can just google "F600 voltage regulator" to find more info
This is the one I ordered
It is basically a really heavy duty version of the F600, You can find them cheaper if you shop around, but this company helped me find the info I was looking for so I bought from them.
Be aware that this is a rare problem, and the solution I provided requires custom wiring so it's probably a good idea to make sure that this is really what you need. The dealer I took my car to in order to get the PCM diagnosed said this is only the second Focus PCM they have ever seen fail and they've been around since well before the Focus was ever thought of.
99.9% of the time if you are having a similar problem, it is the result of the PCM connector going to the alternator/regulator. Wires in these are notorious for breaking. Some alternators even came with a new pigtail at one time.
I would suggest looking into this first.