Newbie to Forum - Have Neglected 850

[DMcQ]

Thank you soooooo much!!!
I can pretty much understand the wiring diagrams but the pictures of the harnesses in the engine don't make it easy to identify what is where. I've been studying those pdf documents and the Haynes manual for quite a while now...just didn't feel confident that I knew where those wires were going. I kind of thought it was the ABS but wasn't sure. The curious thing about those wires is that they were cut clean - no chew marks on them or any other wires in the bundle. And no chunks taken out of them. I wish you could see it too.

I'm not sure you can make it out in the picture(with the fingers) but the unconnected wires are:
2 black, 1 white, 1 yellow, 1 green and white, 1 green and yellow, 1 green and red, and 1 green and blue
I've even been going thru the wiring diagrams asking myself "Where are all the places I would find a yellow wire?" and trying to narrow it down that way.

Storms are gone, taxes are done, so tomorrow I'm going to dig into it.

[DMcQ]

Good old Volvo!!!!!!

I put in a new battery and she started right up. I let her run for a while and as expected, the 'Check Engine' light was still on and now the 'ABS' light is on. I retraced the wires yesterday and confirmed that the broken green wires with stripes on them are ABS sensors.
I don't intent to replace the entire harness. I can fix wires. Not much else I can do automotive but I can do wires.

Which is a good thing because I was going to hook up the OBD2 to see if it told me anything interesting but apparently when they did the last wiring replace someone jury-rigged a cable...wired directly into it from under the dash with a cable hanging out and I think I'll need to pick up a gender-bender at Radio Shack to hook it up. Some more wires to mess with.
I'm proud of my Volvo. Power windows work, AC blows cold,radio even works (but the CD inside it was a bit melted)
Ran for over an hour and didn't overheat or make funny noises.

Thanks everybody for all your help.

[rspi]

LOL, I'm shocked to hear that car started. I probably would have bailed on it. I'm with whomever said replace the harness. Shouldn't be that hard to do and maybe even less time after you practice on a salvage yard car.

I guess some of these systems are indipendant of others and will let the car run. just try not to let anything short out and start a fire.

[Ozark Lee]

We have two resources that might help you here on the site for download.

The first is the 850 factory service manual that has schematics. The schematics are easy to read but they do lack some detail such as junction points.

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

The other resources are the actual factory electrical manuals. They are a pain in the butt to decipher but they are very detailed. Due to the way they are scanned the page numbers are not sequential.

https://www.matthewsvolvosite.com/volvo-wiring-diagrams

...Lee

[DMcQ]

You guys are great!!!!!
I have to go out of town for a few days but here is my plan:
I'm going to repair those ABS wires with butt connectors, heat shrink and F4 tape.
I'm going to try to figure out what this mystery connection is under the dash . It just doesn't look to me like this is something that came from the factory. Below are 2 pictures, the first for orientation and the second showing some detail. A bunch of wires are connected with red tape to a 16-pin serial female connector, then on to somewhere else in the dash. Someone did a lot of work here so I want to find out whether this is something useful or just a mess. Anybody have a guess what it might be?

For orientation

VolvoDashConnector1.jpg (33.19 KiB) Viewed 649 times

Detail

VolvoDashConnector4.jpg (180.63 KiB) Viewed 649 times

I think I can track down the wires and figure out something about it. Or maybe hook it up to my laptop and see if I cen read anything. I really don't know if it was like this when I bought it and the serial cable was just tucked up into the dash or if it was something they wired up when I had the wiring harness replaced for the squirrel damage in the trunk.

Then I am going to try to find the original wiring problem that drained the battery and resulted with the poor old Volvo sitting in the back yard for 4 years.

Next I have an appointment with a highly recommended mechanic to give it a good check out and give me a prognosis. I'll have to sneak it there since the tags expired in 2007 but since they are out of state, usually don't get much attention. I'll get a friend to drive behind me so no one can see the plates.

If it looks like there is hope for it mechanically then I'll consider replacing the wiring harness, although I think I can fix the wires better than new. I don't want to do all the work and expense of replacing the harness if it needs thousands of $ of mechanical work!!

I did find the OBD-2 connection. I thought this jury-rigged wiring was it but the OBD2 connector is in the right place and as would be expected after 4 years of a dead battery, it gave me no useful info but it was able to communicate.

Any other suggestions?

[DMcQ]

i downloaded volvo_850.zip and it says 1995. Should it be essentially the same for a 96? Mine is an early 1996, says it was built Spring 1995.

[jblackburn]

See the wiring diagrams links on the repair database tab. There are links for every model year.

The 1996 is different in several respects from the 1995, namely ABS module and instrument cluster wiring.

[DMcQ]

Thanks!!!

I've been using the 96 wiring diagrams but 'Ozark Lee' also gave me a link to Volvo_850.zip which has lots of useful stuff but it says 1995. Is there an available 1996 version of this or is 1995 good enough for an overview of other things not related to wiring?

[jblackburn]

Whoops. That will definitely cover everything else for you - that's why it's there! 850s are more or less the same between the years with minor differences here and there with wiring.

[Ozark Lee]

Anybody have a guess what it might be?

It is definitely from something aftermarket such as an old cell phone or maybe even an aftermarket alarm. If all of the splices are just taps I would simply cut the old crap out and repair with heat shrink and solder where necessary.

...Lee