Pinpoint B above.
Pinpoint D Below.



Pinpoint-ALL covers all.

 

Hello,

Thank you for the "pinpoint-ALL.pdf"... !

Again thank you ... and will follow up with results..

J

 

Hello. The information that you have provided is more detailed, thorough, and helpful than anything else that I have been able to find. I am having a similar problem with my 2003 Crown Vic. Can you tell me if this information is the same for a 2003? Here is some additional information...alternator was not charging... so I
1) replaced the alternator, but it overcharged at around 18 volts
2) replaced that alternator with a 2nd replacement and, at the same time, replaced the battery with a new one due to the battery being swelled from overcharging
Now the alternator charges properly initially, but steadily rises to 16 volts. I also want to mention that my car has a digital instrument cluster. Right now, I am waiting on a replacement pigtail to the alternator. Once that is replaced, I'm not sure where to turn next. Could it be the PCM?

 

The PCM does control the output of the alt based on the info it receives.

Check the center wire of the plug going to the alt .
If it is always showing 12 or more volts ,the PCM is what supplies that signal to charge. It is duty cycled and if constant , either alt is not providing correct info to PCM or PCM is faulty.
Make sure wires and connections at the plug ( 3 of them) are good and not loose or corroded.
Don't overlook the heavy gauge wire coming off the alt is not internally corroded which would cause the PCM to think the alt is not putting out enough and therefore high output = overcharging.

 

Thank you. I'm guessing that the voltage on the center wire needs to be checked while the plug is attached to the alternator. Therefore, I will check it as soon as the new plug arrives and I get it installed. Also, the splice will provide easy access point for a voltmeter.

 

2003 is the same generation as 2004, so they should be the same.
What you should also check is the battery cables at the battery posts, including the ground cable, make sure they are all clean, and tighten to specs, don't over tighten it as it can cause the same issue as a loose terminal.
+ and - terminals -> 7Nm (62 lb-in)
hold down -> 12 Nm (9 lb-ft)

Ground Locations index page shown above.
Check all the grounds too and never underestimate the importance of ground wires, it's the return path to complete the electrical circuit, especially the ground strap to the engine block where alternator gets its ground from. You can use ohmmeter to verify with one end on battery ground terminal, the other end on other ground points.