1996 850 turbo battery drain

Muhley · Post by **Muhley** » 24 Jun 2015, 10:45

This car has had the drain for a very long time and the owners installed a kill switch under the dash as a band-aid fix. I've hooked up the multi meter and started pulling fuses, fuse 15 has the biggest draw. Its not the glove box light ( I put my phone on video and checked it) and its not the trunk light (checked through the ski hole). Does anyone else have some ideas?

Post by **erikv11** » 24 Jun 2015, 11:07

Check carefully the overhead lights up by the rear view mirror. Are they working properly with the switch in various positions, are the bulbs inserted correctly? Maybe unplug that overhead cluster and see what that does to your draw.

Do the little courtesy lights on the door edges go off when the doors are shut? Bad door latch microswitches are another common problem connected to fuse 15. But that usually is accompanied by overhead light shenanigans because the overhead lights are being told the door is open, when it is not. This one is a bit more arduous to test the draw, you have to pull each door panel and unplug the door latch electronics.

Muhley · Post by **Muhley** » 24 Jun 2015, 13:42

okay thanks, ill give that a try

Muhley · Post by **Muhley** » 24 Jun 2015, 14:36

so I went through and pulled all the door bulbs out one by one and tested to see if they reduced the draw, I also checked the over head lights and the light for the arm rest. the rear red door lights when pulled dropped the amp draw by 5 micro amps. Could the lights in the visor be drawing power? if they are how would I go about disconnecting them?

Also I didn't mention in my initial post that fuse 6 is also drawing power, about 40 micro amps and its for the central lock, I also recently learned that fuse 15 is what allows the fob to work, could the two possibly be linked?

Thanks for the help!

Muhley · Post by **Muhley** » 25 Jun 2015, 10:28

After looking at the wiring diagrams it seems like most if not all of the wires come through the firewall harness (is that right?) connectors 24/13B(yellow bar blue blug) and 24/2B. (white bar blue plug)

: this is the harness under the dash

I started by unplugging every clip in the harness and i got a reading of a 2.5 milliamp draw
next I connected Red bar Green plug and got no increase
Red Blue no increase
Red Red no increase
Red White 2.5 milliamp increase 5 milliamp total draw
Next I connected White bar Green plug 0.9 milliamp increase 5.9 milliamp total draw
White Blue over a 200 milliamp increase which brings the total draw unknown because the reader doesn't go past 200. I removed the blue plug from the white bar and continued on.
White Yellow no increase
White White no increase
Finally the Yellow bar Green plug 2 milliamp increase bringing the total draw to 7.9 milliamp
Yellow Blue 55.8 milliamp increase bringing the total to 63.7 milliamps
Yellow Blue was then unplugged bringing the total down to 7.9 milliamps
Yellow Yellow no increase
Yellow Red plugged in cause an increase of 1.6 milliamps and a total draw of 9.5 milliamps
Yellow White no increase.

Knowing this, would I be able to drive the car without those plugged in? or how can I further refine what is draining the battery without ripping up the entire car?

Post by **abscate** » 25 Jun 2015, 11:09

Scour the Internet for a wiring diagram and read off the white blue bar connectors. That's the culprit.

Post by **erikv11** » 25 Jun 2015, 14:17

Nice detective work. I agree, a wiring diagram is the next step, you are getting close.

Muhley · Post by **Muhley** » 26 Jun 2015, 06:38

new symptoms! I was driving today and there is a faint chime, no interior lights come on and I know i put it all back together right haha

Post by **jgc470** » 26 Jun 2015, 07:12

I had similar problem last fall, a short circuit in #15 fuse line. After working on interior lights, glove box light, etc., I found my problem was the automatic door lock lock/alarm module. The unit is under the dash at the base of the steering column.

Post by **jgc470** » 26 Jun 2015, 07:20

I used the following write up for my work on my 96 854T: https://volvo850wagon.wordpress.com Go to #90 adding keyless entry part 1 I found this to be a very useful site for the 850's.