1986 Volvo 850 Electrical Problem

seetgp · Post by **seetgp** » 14 Sep 2009, 14:44

Greetings,
My 96 850 has an puzzling electrical problem. The windows/sunroof don't work. They worked one day, stopped the next, worked the next, then stopped again. I've had similar occurrences with the electric seat and the blower, both of which are currently working. I checked the circuit breaker (located under the cover in the fuse box) by switching it with the breaker for the electric seat but that didn't fix it. The seat worked with the breaker from the windows/sunroof so I don't think it's the breaker. I did notice though when I was switching the breakers that whichever one I put into the the window/sunroof got pretty hot to the touch. I'm stumped. Can anybody offer any suggestions? i would greatly appreciate it. Thanks Tom

FCPEURO · Post by **FCPEURO** » 14 Sep 2009, 18:03

If the fuse is getting hot, something is drawing a lot of power, just not enough to blow the fuse. I would check to make sure that you are getting power to the switches first and then if you are, see if it is getting to the sunroof motor. Unfortunately, there is no easy way to find the issue without tracing the wires out.

850wagon · Post by **850wagon** » 14 Sep 2009, 20:24

so the fuse itself is getting hot for the windows? make sure first you have the right size fuse installed for them. you really shouldn't be able to feel any heat being generated from the fuse itself. do you have any access to a digital multimeter or test light? id check for power and ground and definately check how much amps are being pulled thru that fuse.

Post by **Ozark Lee** » 14 Sep 2009, 20:39

Electrical problems are always a bear to find but they are easy to fix - once you find the problem in the first place.

A full set of schematics for your car is available here (I assume you meant a 1996):

http://mojevolvo.pl/wiki/Strona_g%C5%82%C3%B3wna

The site seems to be down at the moment. Once it is up it is very slow and everything is in Polish. The schematics are, however, in English.

The 850 service manual here on the site is also very good but it doesn't identify branch points. It is definitely worth the time to download it:

https://www.matthewsvolvosite.com/downlo ... vo_850.zip

...Lee

Post by **BEJinFbk** » 14 Sep 2009, 21:45

I don't see a fuse in this circuit. Just the breaker in position 37.

96 850 Power Windows.pdf: (168.6 KiB) Downloaded 226 times

Same thing with the Power Sunroof.

96 850 Power Sunroof.pdf: (93.45 KiB) Downloaded 158 times

I'd suspect a shorted window switch as a place to start.
Unplug the window switches and see what happens.
If the sunroof works fine, start digging into the window switch pack.

seetgp · Post by **seetgp** » 15 Sep 2009, 10:07

Thank you all very much for your responses.
BEJinFbk suggested to check for a shorted window switch and that's just what it was. A while ago the front passenger side window wouldn't go up so I took the plastic switch cover off and made the connection with a screwdriver just to get the window up and the rain out. Sometime between then and now one of the little metal fins inside must have shifted and made a connection which was causing the current draw and the breaker to get hot. I pulled out the 2 little metal fins inside the switch and now the other windows and the sunroof work again
Many thanks to BEJinFbk for the solution. I really appreciate it!!

Post by **BEJinFbk** » 15 Sep 2009, 12:47

I'm glad it was an easy one. Happy to Help !