2001 V70 2.4T voltage/power issues

[prwood]

We have a 2001 V70 2.4T that's been having some voltage issues over the past week. The problems began when my wife was doing some city driving and pulled away from a stop. She noticed that the pickup was a bit sluggish. A minute later, she saw a "low battery voltage" message on the dash and then shortly thereafter, a "service abs system" message. When she came to another stop, when she put her foot on the gas, the car didn't respond, and after that point it wouldn't start up again.

We had the car towed home, and I checked the battery with a multimeter. The voltage was under 10, so I took it to Auto Zone and had it tested and charged. After it had charged up fully, they tested it and said that everything looked good.

I took the battery back and reinstalled it, and the car started up fine, but I was still getting the low voltage message. In addition, when I tested the battery again with the engine on, it was showing a low voltage between 11-12, and it was actually gradually going lower and lower, so I suspected that the alternator was the issue. I got a replacement alternator from a junkyard and ran through this procedure to replace it:



When I started it back up, the voltage at the battery seemed a bit better, around 12.6, but still not what it should be (around 14v according to this: In addition, when I start up the engine and it's idling at lower rpms, I get the following message: "EL.POWER SYSTEM SERVICE REQUIRED".

I read a couple of threads on this forum:

https://www.matthewsvolvosite.com/forums ... 8&start=10
https://www.matthewsvolvosite.com/forums ... hp?t=36005

These and other threads still seem to point to an alternator issue or voltage regular issue. One thing to mention at this point is that when I installed the replacement alternator, I forgot to put back in the washer that was in between the post and the lead on the alternator (originally it went post|washer|lead|nut). I'm doubting that has anything to do with it but I thought I'd mention it. I guess the junkyard alternator I got could also be bad? It was only $50, but I can take it back for a refund within 30 days. When I picked it up originally and asked about the refund, the guy at the junkyard said that people don't usually junk their cars because of a bad alternator, so he didn't think it would be bad. But clearly it could be. Any suggestions of other tests to run? Maybe I should try just replacing the voltage regulator?

Thanks!

[abscate]

The alternator should be putting 13-14Volts at the battery with the engine revved slightly (1500-2000 rpm) or else it isn't right. Junkyard alternators are usually good, but you test the same way.

If the battery is more than 5 years old it might be bad too.

[prwood]

When I measure the voltage at the battery when the car is off, it's around 13.6, when I turn it on it drops to 12ish, instead of going up to 14ish. Is there a way to tell if that drop is being caused by the voltage regulator, alternator, or battery? Do I just buy a new battery and put it in and see if the problem goes away? I wouldn't be able to return it once I had hooked it up, so I'm hesitant to do that if that turns out not to be the problem.

[nsjames]

grounds. Clean them.

[prwood]

I took the car over to Advance Auto Parts and had them run their starter/battery/charging system test:

* Battery Test "Good Battery" (Voltage: 12.52V, Measured: 873 CCA, Rated: 730 CCA, Temperature: 70F)
* Starter Test: "Cranking Normal" (Voltage: 11.14V, Amps: 0.0A, Time:6.00S
* Charging System Test: "No Voltage" -- "Charging system problem, check belts, connections and grounds. Alternator service recommended if connections are ok."

The battery was manufactured in December 2014, so it's less than three years old and still within its warranty period, but from all indications it doesn't seem to be the issue.

Since I just replaced the alternator, and part of that involved removing and reinstalling the serpentine belt, I was able to check it, and it was in good shape and was routed and seated correctly.

I'm not sure of the location of all of the grounds to clean them - are there any in particular that I should be concerned about?

So since it seems like the battery is good, then my next steps are to clean and check all of the grounds and connectors. If the problem persists then I guess I should suspect the replacement alternator or voltage regular again?

[abscate]

There are lots. Of grounds on these cars and the wiring diagram ( on the inter webs) can tabulate them

It's not uncommon to get a bad aftermarket alternator out of the box, your diagnosis points to test as the problem.

[vtl]

What year was the donor? Alternators from newer Volvo's don't work in old ones, like yours. You need a different voltage regulator, but if you go this way it makes sense to replace bearings as well.

[difflock54]

Check the alternator clutch pulley.
If faulty this causes a gradual drop in voltage often only intermittently.

[prwood]

Check the alternator clutch pulley.
If faulty this causes a gradual drop in voltage often only intermittently.

How do I tell if the alternator has a clutch pulley? I took my old unit in for a test and this was one of the questions they asked - apparently some models have it and some don't.

[difflock54]

Not certain if your V70 has one but the link below seems to indicate your year/model would have.

I had problems recently with my 2002 V40 where the voltage gradually dropped whilst away on a trip to the point that the battery got so low the engine stopped along with all electrics. This occurred with no battery warning light showing at any point till she died.

Left stranded out of town, it cost me a new alternator, alternator pulley and 5 hours labour to get the car going again.
Has been fine since then and when running shows over 14 volts pretty consistently and never under 13.7volts.

https://www.matthewsvolvosite.com/forums/vie ... php?t=3400

This link helps explain basically how they work and how belt slip can occur when they start to fail.

https://www.gatestechzone.com/en/proble ... tion-tests