1997 Volvo 850 sedan, non-turbo, plethora of electrical problems

Ah, the ghost is in MY machine......so I have a '97 Volvo 850 sedan, non-
turbo, and I think it may be possessed. I've owned the car for about two and
a half years, and for the first year or so the dash lights would randomly go
out while I was driving, usually after hitting some kind of bump or dip in
the road. I would pull over, turn the car off, and restart and the lights
would be back on. After a year or so of this the lights stopped working
entirely and then, a week or so later, they began working perfectly and I
haven't had a problem (with them) since...I think my car aspires to be a self-
cleaning oven....

Now for the real problems....

The fan blows on low when the max/min slider is in the max position, but
sometimes it surges into high, then back into low. In any other position,
including off, it will blow however hard it wants to for however long it
wants, usually switching between high and off or low every ten seconds to one
minute. The doesn't match up quite right on the dash gauge...it never
really looks like it's on max, but it doesn't move any farther to the left.

The cigarette lighter doesn't work, but I really haven't tried to fix that
yet. I assume I'll probably just need a new one.

The seat heater randomly turns itself off and on. This is a relatively new
development and it doesn't seem to turn itself on very often, however when I
try to keep it on, it usually turns itself off after a while. Sometimes it
comes back on, sometimes not.

The Winter button doesn't seem to do much...or if it does I can't tell what.
I did get it to turn on once, but then never again.

And last, the running light on the rear passenger side no longer works. I've
changed the bulb, checked the wiring going into the array, and cursed at it,
but nothing seems to have helped.

Any ideas, or shall I call for a priest?

 

My son had similar problems on his car, with randon electrical faults.....In
the end I took a day of work and set about every relay, fuse, plug and
socket I could find. The culprit was a loose pin in one of the multi-pin
plug and sockets that are a feature on modern cars. As in your case going
over a bump would make things work or fail.

Take a day off and have a go.Its very character building, get your loved one
to ply you with cups of tea and don't go anywhere near the cat!!

ttfn.....Alistair

 

Take a day off and have a go.Its very character building, get your loved one

Thanks Alistair...sounds like it'll be a frustrating but interesting day...
and I'll pass along the warning to my kitties!

 

There are several possibilities.

1) was the vehicle ever in a flood? That would create these problems.

2) a ground fault. This is a ground connection that has a poor
connection. The battery has two connections: the hot and the ground.
Unfortunately the ground frequently goes to the chassis which has many
joints. The joints should either be welded or strapped but the straps
aren't always tight.

3) a loose connection. As the other response intimated, any connector
or fuse can develop a resistive connection. This is usually remedied by
removing and replacing all fuses and disconnecting and reconnecting all
connectors. There are connectors everywhere: relays, modules, lights,
etc. Also, it is advisable to remove and put back every lamp.

4) while doing the loose connection drill, you may discover a broken,
loose, or abraded wire as well as skinned knuckles.