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  #1  
Old 11-06-2016, 05:39 PM
TheDon's Avatar
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Odd W123 battery drain

Out of the blue there seems to be a drain on the battery with the car parked. Pulling fuse #2 stops it. When fuse 2 is in there is a draw of 12.64 volts across the negative terminal to the negative battery cable, fuse 2 pulled and it's a 0.15 volt draw which is the clock I assume.

Fuse 2 has

Clock, trunk light, diagnostic, switch-over valve,seat back arrester, roof light front and rear, hazard warning system, automatic anenna, illuminated vanity mirror, warning monitor term 5, (electronic radio)

I've pulled the clock, trunk light, vanity mirrors, radio, and interior lights front /rear. Not sure what warning monitor term 5 is or diagnostic.

Anyone else come across an issue with fuse 2 like this before? I need to find a wiring diagram and see what fuse 2 truly covers.

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  #2  
Old 11-06-2016, 09:30 PM
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Quote:
Originally Posted by TheDon View Post
Out of the blue there seems to be a drain on the battery with the car parked. Pulling fuse #2 stops it. When fuse 2 is in there is a draw of 12.64 volts across the negative terminal to the negative battery cable, fuse 2 pulled and it's a 0.15 volt draw which is the clock I assume.

Fuse 2 has

Clock, trunk light, diagnostic, switch-over valve,seat back arrester, roof light front and rear, hazard warning system, automatic anenna, illuminated vanity mirror, warning monitor term 5, (electronic radio)

I've pulled the clock, trunk light, vanity mirrors, radio, and interior lights front /rear. Not sure what warning monitor term 5 is or diagnostic.

Anyone else come across an issue with fuse 2 like this before? I need to find a wiring diagram and see what fuse 2 truly covers.
battery draw is not measured in volts, are you sure you're not talking about MA. also, if the clock is truly off of the circuit for fuse #2, then the remaining 0.15 ma (volts?) has to be something else. if you google "parasitic battery draw" there are a number of videos on youtube that although are not specific, the same principles still apply to your car. also what year is your car? and is it sedan, coupe' or touring car?
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  #3  
Old 11-06-2016, 10:09 PM
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It's in my sig.

What am asking for is would anyone know off hand what else is on that circuit since the descriptions aren't exactly forthcoming. I still need to dig up a wiring diagram.
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  #4  
Old 11-06-2016, 10:37 PM
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I don't have a specific answer but if you do something like removing the Trunk Light Bulb you can eventually find it by disconnecting stuff.
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  #5  
Old 11-06-2016, 11:04 PM
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Quote:
Originally Posted by TheDon View Post
It's in my sig.

What am asking for is would anyone know off hand what else is on that circuit since the descriptions aren't exactly forthcoming. I still need to dig up a wiring diagram.
First off from what you are describing " across the negative terminal to the negative battery cable" is meaningless as someone already stated. But that's another discussion.

The "seat back arrester" only applyies to coupes, the "warning monitor" is a relay type box located under the driver's side dash, above and on the passenger side of the parking brake foot pedal. The module has connections to the Key warning buzzer, the headlight buzzer, set belt warning indicator, brake fluid level switches, driver's door switch, the "blue exciter wire to the alternator and a few other inputs, outputs and ground.

"Hazard Warning System" is the emergency or four way blinker system.

I can't find anything about "diagnostic".

If you could determine the current flow between the battery negative terminal and ground that would give an idea as to how much power was flowing and in doing so draining the battery. The amount of the drain might give a better idea as to what is actually consuming or draining away any current flow.
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Old 11-06-2016, 11:19 PM
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Please rephrase what you actually trouble-shot. The units do not make sense (volts/amps as you described what you measured).
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  #7  
Old 11-07-2016, 08:05 AM
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Measuring volts with the meter In series with the circuit as you have done gives meaningless results. What you want to measure is amps.
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  #8  
Old 11-07-2016, 09:08 AM
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yeah I realize that now, that black magic "lectricity" has never been my strong suit.

ill hit it again today and measure amps across the gap instead of volts. I did remove the interior bulbs, trunk bulb, and glove box bulb to remove those from the equation.
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  #9  
Old 11-07-2016, 11:30 AM
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Have you checked out the voltage regulator .
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  #10  
Old 11-07-2016, 02:38 PM
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I have not because the car can sit overnight without killing the battery if I pull fuse 2.
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  #11  
Old 11-07-2016, 10:23 PM
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Power antenna is always a suspect. Easy enough to disconnect it and see what happens.
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  #12  
Old 11-13-2016, 05:18 PM
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Does it have a factory alarm? If it's a 1983 model it may not so I wonder about the electronic radio (which came out in 1984-1985) and the seat back arrester seems like the fuse box diagram may have come from a coupe version.
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  #13  
Old 11-14-2016, 01:41 PM
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check that all secondary grounds are secure
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  #14  
Old 11-16-2016, 09:00 PM
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Quote:
Originally Posted by MBeige View Post
Does it have a factory alarm? If it's a 1983 model it may not so I wonder about the electronic radio (which came out in 1984-1985) and the seat back arrester seems like the fuse box diagram may have come from a coupe version.
possibly? But the aftermarket radio is on the same fuse. I have time this weekend ill retest the system to see if I can track it down. Electrical gremlins are the worst
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  #15  
Old 11-17-2016, 09:15 AM
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Quote:
Originally Posted by TheDon View Post
yeah I realize that now, that black magic "lectricity" has never been my strong suit.

ill hit it again today and measure amps across the gap instead of volts. I did remove the interior bulbs, trunk bulb, and glove box bulb to remove those from the equation.

Joe, consider checking out the trunk lamp and connections. On 3 W123s (including the one I bought from you) I have had to clean up the truck lamp socket which collected corrosion and apparently shorted out. I am not an electro genius either, but I took a short course from a Volvo dealership up here and that's how I discovered it. Apparently parasitic drains attack Volvos and they have a good little course on it. I think there's also a write in the Volvo forums.

PM me if you have questions.

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