04 XC70 electrical problem

**daver1100rt** · 08-02-2019, 08:28 AM

Hello XC folks- 04 XC70 with a pile of miles, my son was driving the other night and got stranded about 15 miles from home with a dead battery. Car quit while he was driving it. He said he noticed the red battery light was on while he was driving it. Which several battery to battery recharges (from my 03 XC70) we limped her home safely. Message about "Electronics Service Needed" was on the message display.

I charged the battery for about 20 hours and the green light came on- "charged". She starts and runs but I still have the Service message on and the little red battery light is on. The battery is a cheapo from WM that the previous owner put in about 10 months ago, (I bought car last February) so if it just needed a battery it wouldn't surprise me. But to me when batteries go it's dead when you try to start it on a chilly morning, not while you are driving on a July evening.

I'm thinking it's more than a battery problem. It had some weird engine codes when I put my scanner on it, to me unrelated to battery charging. It was doing all sorts of electronic convulsions as I drove it home with limited electrical power, I figured those codes were just the car being confused. I just cleared those codes and will watch for them to reappear after this "battery" problem is sorted out.

Any suggestions? Thanks. Dave in Marcellus NY

**Willy** · 08-02-2019, 08:47 AM

The red light indicates that the battery isn't being charged.
Possibly there is a problem with the alternator or the poly V-belt.

**AKAMick** · 08-02-2019, 09:00 AM

Try a new brush set for the alternator, cheapest solution if the belt is good, might be all it needs, then again might not.

**hoonk** · 08-02-2019, 11:36 AM

Originally Posted by daver1100rt

after this "battery" problem is sorted out.

Any suggestions?

The red alternator (with battery icon) light on means the alternator is not charging. Technically it comes on because the alternator is putting out less voltage than the battery has in it. Simple to test with a voltmeter. With engine off, attach voltmeter to battery or + terminal under hood and ground to read static battery voltage. Note value, should be ~12.4 volts with fully charged healthy battery. Start engine and voltmeter should go up to at least 13- 13.5 volts depending on the state of battery charge - with a small electrical load, (rear defrost, ac off). If it's charging when the alternator is cold, warm up the car and make sure it still charges when hot, thermal expansion can pull the almost worn out brushes away from the commutator. If/when charging make sure it continues to charge above 12.5 volts with ac and multiple accessories on, testing above idle speed.

The battery may be weak or could have been weakened if it is older by completely discharging - but your symptoms are that of a bad alternator.

In general the red warning lights or triangle mean stop the car now before something worse happens (alternator, oil pressure, brake are red lights) orange warning lights mean caution (bulb out, washer fluid, etc)

**imst0ked** · 08-02-2019, 11:41 AM

When looking for a new battery, I'd go with the Volvo one. My battery hasn't been changed in the almost 12 years I've had the car and unless the previous owner changed it in the first 2 years, it's original. The car is a 2006.

**hoonk** · 08-02-2019, 01:23 PM

Originally Posted by imst0ked

When looking for a new battery, I'd go with the Volvo one.

In my part of the US, Interstate battery sells to the dealer and puts Volvo stickers on them, then would sell the same battery to my shop with an interstate sticker.

One reason they last so long is the location in the trunk is cooler.

**daver1100rt** · 08-02-2019, 01:58 PM

Yeah, I was thinking alternator too. I'll do the voltmeter test tonight and see what I find.

if it does need an alternator it would be really cool if I could just solder new brushes in there. I haven't done that trick since 1987 with my 79 Rabbit! I seem to remember that was about a $5 repair. Dave

**daver1100rt** · 08-02-2019, 04:22 PM

Yes, looks like alternator. 12.55v engine off, 12.11 engine running. Im seeing 200 bucks plus for alternators (paid $400 for the car). So im REALLY interested in swapping out those brushes. Or I could dig an alternator out of the junkyard for less than 20. I'll report back when ive got the dead alternator extracted. Dave

**hoonk** · 08-02-2019, 06:23 PM

Originally Posted by daver1100rt

im REALLY interested in swapping out those brushes.

Brushes are built into the voltage regulator, 2 phillips head screws hold it onto the back of the alternator, I remember they are very difficult to get to with the alternator mounted or the intake manifold on

**Willy** · 08-02-2019, 11:44 PM

Originally Posted by daver1100rt

Yes, looks like alternator. 12.55v engine off, 12.11 engine running. Im seeing 200 bucks plus for alternators (paid $400 for the car). So im REALLY interested in swapping out those brushes. Or I could dig an alternator out of the junkyard for less than 20. I'll report back when ive got the dead alternator extracted. Dave

You may also have a look at the tension of the belt. I once had an alternator that slipped without making noise.