Hi, I have a 2004.5 S40 (late year, early chassis model) and my alternator needs to be fixed and replaced. With a multimeter, the battery has voltage 11.8 when running, 12.4 when engine is off. I originally had a 5-year-old dead battery and I replaced it, but then found that the alternator wasn't working well. I've checked the wires from the B+ output from alternator to + terminal, and from the - battery terminal to alternator body, and both have a voltage drop of only .02 volts. So it looks like it is definitely the alternator. Here is where it gets fun.

The alternator number is Denso 10210-4050/Volvo 30667051/Form 3M5T-10300-UA. It is a two-pin model.

Looking online, I find all the parts catalogs say that I should have the Denso 210-0843 (Volvo 8602920) alternator. The Densoparts catalog online doesn't list 10210-4050 (or 210-4050) as an alternator. Are the two alternators (210-0843 and 210-4050) the same model? Denso is selling a rebuilt 210-0843 for $250 (including body) and if they are the same, I may buy that.

Finally, from what I've read, it may be the voltage regulator that should be replaced. Does anyone know the part number for this regulator? The only place I find online selling the voltage regulator is Voltage Regulators 333719 Regulator Replacing: VR-H2005-176 - Delcoribo in China and similar sites on ebay/aliexpress. It appears to be Mobiletron part VR-H2005-176, but I haven't been able to find that part anywhere.

Last question, would anyone recommend buying the aliexpress/ebay regulator and installing it in the alternator? The cost is $30 (versus the $250 for a rebuilt regulator).

My skills are: have pretty decent DIY skills (replace spark plugs/ignition coils/oxygen sensors, but this will be the first engine issue I'm tackling).

Thanks in advance for your help!
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The "crossover year" thing can get kind of confusing. I'd say that it would be a good idea to just make very sure that the alternator you get matches the physical (mounting and plugs) of the original. The rockauto cross-references are usually very good, but the 2004.5 Volvo thing can be a stinky wrinkle, so make sure you get one that'll work.

FWIW, the rebuilt alternators on rockauto.com seem to be quite a bit less than you're looking at - worth a look.

I'd be hesitant to replace just the regulator, sourced from "who-knows-where". That sounds like it could go bad in one or more of several different ways.

 

check with a dealer web store like Tasca Parts and you'll see Volvo 8602920 for the 2004.5 and 8603496 for the 2005+

EEuroparts sells the Denso:

https://www.eeuroparts.com/Parts/442...nator-2100843/ see if the chassis number listed agrees with your VIN.