My 1997 Volvo 850 sedan with 152k miles on it appears to be having some battery drain. So I disconnected the battery, connected the negative terminal of the battery, to the negative prong of my multimeter, the positive prong of the multimeter to the negative lead from the car and got a reading of 0.137. (The multimeter was set at amps first, because that is where I got a reading, the recommendations appear to be that we go down from amps to milliamps, and so I presume that this is amps we are talking about, and this is therefore likely huge.) Then I took out the Fuses #15, #6 and #7 in that order. It took down the current reading to 0.032, 0.006 and then 0.004. Removing any other fuse does not reduce the draw to below 0.004. From the chart provided by Volvo, it appears that Fuse #15 is for “courtesy lights, diagnostics, door open warning lamps, (remote keyless entry – which the car does not have), glove compartment lamp,” Fuse #6 is for “central locking” and Fuse #7 is for “Radio/amplifier.”
Question 1: I presume that the draw on Fuse #15 is the one that is major. Given that is covers such a large number of items, how do I go about finding the specific issues? My sense is that I will try a few of the easy ones, if they do not fix the problem, I take it to the dealer, which it is time to do anyway, for a major 150k service.
Question 2: What about the draws on Fuses #6 and #7. Are either of them major?
I was not able to detect whether the bulb was hot enough because it has a cover, but manually keeping that light switch pressed down brings the reading down to 0.008.
What I do not quite get is why without Fuse #15, I am down to 0.032, but with Fuse #15, and the glove compartment lamp button pressed, with Fuse #15 in place, I get 0.008. Why this discrepancy, or is it measurement error? I am using the Amps setting of the multimeter.
The radio is OEM, though I seem to think that it was replaced before I bought the car (certified pre-owned from Volvo in 2000). The drop is always the same in terms of differences. Fuse #6 brings it down by around 0.026, Fuse #7 brings it down by 0.02. The other fuses do not change the meter at all.
Right, which I do. But this is a battery drain issue. I was trying to find the cause and that appears to be that the glove compartment lamp does not switch off when that door is shut.
I think it would be surer to remove the light bulb since there is no way to know whether the light is out when the glove compartment door is shut. However, it does not seem to be that straightforward. Disconnecting the light would be another option too.
One possible explanation is that by removing fuse 15, some other system is not satisfied and is staying awake. Assuming everything else was equal between the measurement taking for each scenario.
As you noted in the first post, fuse 15 is involved in the following:
With the fuse out, the circuits it serves may not fulfill their intended function and report to other systems the successful completion of certain diagnostics. This may keep something else awake waiting for a response. It’s all speculation however. Regardless, if you disable the glovebox lamp and leave fuse 15 installed, the draw drops to 8mA which is no concern for parasitic draw. Problem solved!
It’s common for current draw to remain high for some time after the doors are closed or a fuse is put back in and then it drops down to permanent low draw. It may have to do with how long you waited to check the meter after closing doors or messing with a fuse.
Does that car have a front roof light that fades out with some delay after the doors are closed?
I see, thank you! With regard to your question, yes, it does have such a front roof light (I think it is an option that I have set according to that). However, for additional information, I did not open the door, and the battery drain test was done with the battery disconnected, and I had the window open to be able to check the glove compartment light without opening the door.
137 mA parasitic draw is barely above what most mechanics would consider to be the limit for an OBD II technology car like your Volvo. Think of it this way: The battery holds roughly 40 amp-hours. A 137 mA discharge would take 12 days to discharge the battery.
137 mA is a little on the high side. My OBD I Corolla’s everything off discharge is 3 mA. But I doubt the 137 mA is caused by the the glove compartment bulb. If the glove compartment bulb is the incandescent type, it’s power consumption (when on) is probably around 5 watts. Power = voltage * current, so the bulb’s “on” current = 5/12 = roughly 500 mA. So the 137 mA isn’t being caused by that bulb. Morelikely the problem is a faulty door switch is making the computer think somebody is getting in the car, which keeps all the computer’s awake. Or it could be that you aren’t waiting long enough for the measured current to drop to the everything off state. Not that some computer may be able to detect the hood is open, and that will keep them awake.