2002 S60: alternator/voltage regulator going out (or computer issue)?

[abscate]

Put your battery on a 10 amp charger for a day, out lights on for a minute , then measure voltage.

If it’s more than 3 years old it is suspect, and a simple bad battery will cause lots of problems

Cranking is not a sufficient test for a good enough battery.

[oragex]

True. Too many people think a battery goes bad only when it's no longer cranking. As batteries wear, they can no longer be fully charged - the maximum charge drops from 100% to 80%, to 60% and so on. A battery can still crank at 12.0v and 25% of maximum charge, but by that time such battery is very very worn and can put stress on the alternator.

[moonweasel]

I don’t have a 10A charger...

What about hooked to another car’s (known good) battery with jumper cables — if I turn on the car then, and it’s still doing the pulsing, that would imply it’s the voltage regulator right?

[abscate]

Take the battery out of the good car and insert into car under test

A battery that works in another car might not be good enough to work in a P2 Volvo. Though

[moonweasel]

I finally installed the new voltage regulator last night, and it did indeed fix the power pulsing (and a few random O2 sensor type codes that I suspected were because of the low power). Brushes were super worn down on the old one (see photo).

Ran the car for a while to charge the battery up, and will check shortly to see if the battery held that charge overnight.

Also need to finish putting the PCM box back together, as I couldn’t get it on last night and got tired of wrangling with it. Probably just need to move the power steering reservoir out of the way to do it.

One last question on this topic:

The replacement regulator that came from FCP Euro is a different part # from the old one, and forum info I could find is conflicting: one place said my new part number is for the turbo model (my car is the non-turbo), and that you have to have the right one. Another place said the parts are interchangeable. Can anybody confirm which is true?

The part number for the non-turbo, which my car had, is BR14-M1-V14. The one that I received (and installed) is BR14-H1. Is this ok, or is something going to be damaged or not work correctly if I leave this on the car?

[IslandV70]

I am not sure about the regulator versions, but back a couple of posts I can say with modern cars a bad battery can cause numerous issues. Our Avalon was suffering with some erratic voltage readings and would throw ABS or Traction Control codes. A new battery fixed it totally.