2002 XC70 Battery drain

[bercy46]

Hi,

I have a battery drain problem.

The battery is new. I unhooked it yesterday, left it there for a couple of hours, and it kept its charge.

I have a multimeter that can measure amps, but its fuse has popped, so all I can do is measure voltage unfortunately.

I have tested each fuse in all 3 fuse boxes when car was stopped (under hood, driver, cargo), and here are my readings, with the multimeter set at 200 mV :

Fuses under hood : all 0 volt.

Fuses in cargo : all 0 volt.

Fuses near driver:

Fuse 16 : 0.1 to 0.3 (2 readings gave two different values)
Fuse 23 : 1.0
Fuse 24 : 2.1
Fuse 27 : 1.2
Fuse 28 : 0.8
Fuse 32 : 7.1, and 8.1 when glove box open and light on

Can anyone with experience with XC70's tell me if any of those numbers are out of whack ?

Thanks.

[abscate]

You will need an ammeter to diagnose that problem, the voltage readings won't mean too much. It needs to go between the battery and disconnected negative cable.

In a pinch, you could bridge the same circuit with a 10 Ohm, 10 watt resistor and then measure voltage drop over the resistor, but that store would have a replacement resistor for your meter!

[bercy46]

Ok, got my hands on a replacement fuse for my multimeter.

I had it set at 2 (amps).

With the car off and all doors/lights closed, I had a reading of 0.180.

I tried removing all of the fuses for which there was voltage the other day, one by one, taking a reading at each step.

Most of them reduced the amps by anywhere from 0.01 to 0.03 amps.

Fuse #32, when removed, resulted in a reading of 0.012. So, it would seem this circuit is responsible for 0.168 amps (168 mA if I'm not mistaking).

That circuit is used for the Central electrical module, vanity mirror/interior/glove compartment lighting, and power steering.

I've checked the lights, they're all off when doors are closed.

This would leave the power steering and central electrical module.

Any simple test I can do to pinpoint the problem ?

Also, if it does point to the CEM, I've searched a bit and it's pretty expensive, can this thing be repaired or do you really need to get a new one ? And how hard is it to replace ?

Thanks.

[div4scpro]

not sure if this happens in your model. I have a 2009 S60. It has a function where the ventilation fan runs after the vehicle shuts off. you may not know it's happening because it's may start after you leave the vehicle. Volvo says that it is so there is no condensation, mold, build up in the evaporator? this function can only be shut off by a dealer? with a software mod. don't know if this will be a solution but I'm trying to find an Optima yellow-top for my vehicle.

[IMSITTINGINYOURCHAIR]

On my 2004 xc70 the fan only runs for five minutes after an hour has passed. I've caught it several times and it always shut itself off. but a reading of just .1 amp shouldn't kill a battery. (our phones pull an avg of 500 ma@5v when charging, as an example.)

You may want to watch the car for the time period it takes to kill the battery to see if anything comes on and raises the current (set it at 10 amps and don't allow it to pull more than about 8 for more than 20 seconds)

[bercy46]

On my 2004 xc70 the fan only runs for five minutes after an hour has passed. I've caught it several times and it always shut itself off. but a reading of just .1 amp shouldn't kill a battery. (our phones pull an avg of 500 ma@5v when charging, as an example.)

You may want to watch the car for the time period it takes to kill the battery to see if anything comes on and raises the current (set it at 10 amps and don't allow it to pull more than about 8 for more than 20 seconds)

This week, I didn't use the car for 48 hours and it still started (almost didn't though). So I doubt that something turns on and drains the battery by itself. Unless it's an intermittent problem... So watching the car for that long is not practical I'm afraid.

What I'd be curious would be for someone with an XC70 to test that particular fuse (#32) for Voltage, and then test the amps with and without that fuse when car is off.