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2002 S80 Parasitic Drain detected on CEM and security fuses

Help, Advice, Owners' Discussion and DIY Tutorials on the Volvo S80 model. Sometimes called an "executive car", the S80 was and continues to be Volvo's top-of-the-line passenger car.
Ohmomovovo
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2002 S80 Parasitic Drain detected on CEM and security fuses

Post by Ohmomovovo » Mon Apr 20, 2020 5:00 pm

The car goes dead after sitting for about a day or two. To see what was going on, I first did a draw test by measuring amps with my meter in series with one probe on the ground cable connected to battery and the other probe on the battery negative post.

This showed me there was in fact a draw so I started to pull fuses.

After sometime, I found a probable source. I noticed that the amperage stabilizes to 0.01A with fuse 32 removed. This fuse appears to feed the CEM, power steering, glove compartment lighting, and other courtesy lighting sources. I also noticed that there is a draw on the security fuse at 38 also.

With fuse 32 in, current cycles between 0.1A to 0.3A. Additionally, I notice there is a current draw on fuse 38 when fuse 32 is left in. There is something going on between the circuits for fuse 32 & 38. What it is, I can't begin to guess because the alarm siren doesn't seem to work anymore and only lights flash when the alarm triggers.

PS I also noticed that the fuel door is broken so it doesn't lock into place. It didn't seem to make a difference when I pulled the fuse related to it in the trunk.
2002 S80 6cyl

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oragex
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Re: 2002 S80 Parasitic Drain detected on CEM and security fuses

Post by oragex » Tue Apr 21, 2020 3:34 pm

The 38 would be the alarm siren, surely bad by now, just leave the fuse out

The 32 seems to the the CEM but not necessarily the entire module, may be just one of the square relays on it

Fuel door actuator always goes bad, pretty expensive, but it won't drain current

http://new.volvocars.com/ownersdocs/200 ... a.htm#pg96

Ohmomovovo
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Re: 2002 S80 Parasitic Drain detected on CEM and security fuses

Post by Ohmomovovo » Tue Apr 21, 2020 8:51 pm

oragex wrote:
Tue Apr 21, 2020 3:34 pm
The 38 would be the alarm siren, surely bad by now, just leave the fuse out

The 32 seems to the the CEM but not necessarily the entire module, may be just one of the square relays on it

Fuel door actuator always goes bad, pretty expensive, but it won't drain current

http://new.volvocars.com/ownersdocs/200 ... a.htm#pg96
The part of the fuel door with the circular hole is broken off.


I also tried removing fuse 38, but if I recall correctly, it increased the current draw. From what I see in a wiring diagram I found online on manualslib and what I read in the owners manual, the alarm will sound if fuse 38 is removed. So, it looks like even though the siren is dead, the CEM has some other component wake up when the fuse is removed.
2002 S80 6cyl

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SuperHerman
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Re: 2002 S80 Parasitic Drain detected on CEM and security fuses

Post by SuperHerman » Wed Apr 22, 2020 8:04 pm

You can try pulling the connector to the alarm siren. Sometimes you can get to it by pulling the passenger side headlight and snaking your hand back there. It is possible the battery in the alarm leaked (they almost always do with age) and created a short.

Are there any relays showing in the schematics? Maybe one is sticking.

Ohmomovovo
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Re: 2002 S80 Parasitic Drain detected on CEM and security fuses

Post by Ohmomovovo » Fri Apr 24, 2020 1:37 pm

It was the alarm siren! The current went up to like 4A for a few seconds after connecting the battery and then it started hovering around 0.1to 0.3A. Once I pulled the connector out of the alarm, it dropped down to a stable 0.01A.

The front headlight was all busted up so it wasn't hard to pull it out, but it was a real pain to pull the alarm connector out. I'd definitely recommend the longest handle 10mm wrench you can find to unscrew one of the two nuts holding the alarm in.

Also, I had to make sure to engage the door lock latches for quick testing. When I didn't, it would take over 10 minutes to get the car to shut down fully. When I did it took only a couple minutes or so for everything to shut down all the way.
2002 S80 6cyl

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