V70 T5 2002 dead battery trouble

Jeffrey Shomper · Post by **Jeffrey Shomper** » 28 Dec 2007, 00:00

Vitals
2002 Volvo V70 T5 wagon
~65k miles
Seattle Washington, USA

We bought this car used in 2004. Within about six months of purchase, I recall having intermittent dead/low battery problems that are noticeable when I try to start the car. Originally, this only happened once or twice a year. These problems have increased in frequency over the last six months and now occur every time I try to start the car.

*interior lights come on but are dim
*under the hood is a rapid clicking noise, but no engine turnover
*stomping on the gas pedal sometimes gets the engine to start
*jumping the car always gets the engine to start
*never a problem while driving, but sometimes the car can be parked for as little as 35 minutes and the problem occurs.
*on our third battery since 2004, current battery is 4 months old.

Vehicle was in the shop twice for this, but no fixes. Mechanic suspected a faulty electrical draw in the alternator (short circuit) but was not able to diagnose for certain.

Reading these and other forums, I've seen the following diagnoses for similar sounding problems:

1) Open circuit in the cooling fan keeps fan running after engine shut off. (I've noticed the fan runs after cutoff, but I've never timed how long)

2) Glove box light remains on (I doubt this is the case but will check)

3) Negative Battery cable creating short circuit (This sounds like a long shot)

Any advice? Think this would be solved by any of the above diagnoses or is it something else? I have a battery charger, any diagnostic tests to suggest?

thanks in advance.

-j.

sony2000 · Post by **sony2000** » 28 Dec 2007, 08:34

A way to test for a short circuit in one of the many circuits MAY BE through the fuse box. Remove a fuse and see if there still is continuity (flow) across the contacts with the key off. If you suspect one circuit, drive the car without the fuse, and the battery should stay charged. All this is assuming someone has at sometime, tightened the alternator belt.

Post by **billofdurham** » 28 Dec 2007, 13:01

The belt is self tensioning so should not cause a problem.

Bill.

sony2000 · Post by **sony2000** » 30 Dec 2007, 11:42

Sometimes the self tensioners are KAPUT! Your gradual loss of charge from this is, more likely than a sort circuit that increases its effect with time.

Jeffrey Shomper · Post by **Jeffrey Shomper** » 30 Dec 2007, 14:37

Okay, we did the fuse box test and came up with confusing results. All of the following are drawing about 10v off the weak battery.

#5 PCV valve and fuel leakage pump
#6 Computer (ECM)
#8 AMP AC Compressor
#17 low beam headlights RH
#18 low beam headlights LH
#20 high beam LH
#21 high beam RH

despite this power draw, the headlights are definitly not on while the car is switched off.

Could some central circuit, perhaps associated with the computer, be open and causing all these other circuits to light up?

sony2000 · Post by **sony2000** » 30 Dec 2007, 18:15

Very good! Only #6 and most likely #5 need their fuse to operate the car. The A/C compressor could be disconnected at the unit itself, if necessary later. Starting the car with a week battery in the less fuses state, running it for 30 minutes, may yield a charged battery. If it does, then add back a fuse at a time until the problem returns. On the airplanes we could turn off all the electrics, then add one circuit at a time to find where the electrical fire got its electricity.

Post by **JRL** » 30 Dec 2007, 20:24

sony2000 wrote:Very good! Only #6 and most likely #5 need their fuse to operate the car. The A/C compressor could be disconnected at the unit itself, if necessary later. Starting the car with a week battery in the less fuses state, running it for 30 minutes, may yield a charged battery. If it does, then add back a fuse at a time until the problem returns. On the airplanes we could turn off all the electrics, then add one circuit at a time to find where the electrical fire got its electricity.

WEAK (battery
The day of the WEEK is Sunday

Jeffrey Shomper · Post by **Jeffrey Shomper** » 01 Jan 2008, 21:45

More detail on the fuse box test - I think I'm getting somewhere

The results I listed above in my last post were achieved by putting the positive multimeter lead on the positive battery terminal and the negative multimeter lead on the fuse terminal inside the box once the fuse was pulled. The measurement was volts.

I now don't think those results tell me much. I just went back to the box, pulled the fuses one by one and measured amps across the two terminals to see if any current was running through the circuits.

With the car turned off, number 5 (PCV valve and fuel leakage pump) was drawing 1.5 amps when I put the leads on, then I watched it go down to 0 amps after about 10 seconds. Sure enough, the car wouldn't start after that. I put the fuse back in, jumped the car easily, drove it for 30 minutes then repeated the test and it showed about 1.8 amps going through fuse number 5.

I pulled the fuse before it went to zero and left it out. I'll check it again in a few hours to see if
a) the circuit still wants to pull current even when the car is switched off.
b) the battery still has a charge since number 5 was disconnected and shouldn't have drained it these last few hours.

Who thinks I'm on the right track? I'm about to go back to the dealership and have them focus on this circuit. Any other advice before I do would be appreciated.

-j.

sony2000 · Post by **sony2000** » 02 Jan 2008, 12:35

Jeffrey, you can go further if you like. With #5 pulled does the car operate normally. If yes, then add #8. If still runs well and the battery is getting stronger then add all the head light fuses. Does anyone know the function of the units connected to the #5 fuse, and which one could likely develop a short circuit?