HELP!! Strange electrical problems with my 850

adrianmitu · Post by **adrianmitu** » 18 Nov 2005, 11:51

Some strange things happening all of a sudden:

1. The left headlight stopped working, both high and low beams
2. The dashboard instrument lights stopped working. The warning lights are OK, however and the instruments themselves also work.
3. The check-engine light is on. I extracted the code and I got 443: Rear knock senor.

I checked all the fuses and they are all OK. Also the engine appears to work fine.

Very puzzling problem. Can anyone help me? Thanks!
Adrian

Post by **dosbricks** » 18 Nov 2005, 19:00

We assume the headlight bulb is not burnt out. Check the wiring directly behind the bulb socket. Sometimes the insulation can get brittle from the heat of running with the lights on all the time. If it flakes off, the hot wire can ground.

The knock sensor wiring harness was the cause of my having to replace mine. Volvo introduced a re-designed harness/sensor kit. so it must be a common problem with the originals.

To change the knock sensors you have to pull the fuel rail and the intake manifold, but neither is too hard. The fuel line can remain on the rail (stays pressured up), and remember there is a low center bolt on the manifold that is difficult to see. Also a good idea to replace the manifold gasket.

Guest · Post by **Guest** » 18 Nov 2005, 20:51

I'll take a quick jab at this, but could the head light control switch? Because that controls the dimmer switch (above the rear fog light switch). If that fails, a lot of stuff wouldn't work as well.

www.fcpgroton.com does sell a headlight switch: http://www.fcpgroton.com/volvo850other.htm

Its worth a shot, if the fuses aren't burnt...

Post by **MadeInJapan** » 20 Nov 2005, 18:40

There was a recall some time ago on the light switch...check with your dealer to see if it included your specific model.

turbotim2 · Post by **turbotim2** » 21 Nov 2005, 08:24

You may also want to check your ignition switch, I have seen them knock out different lights and accessories in them as the switch gets worn.

Guest · Post by **Guest** » 21 Nov 2005, 14:25

turbotim2 wrote:You may also want to check your ignition switch, I have seen them knock out different lights and accessories in them as the switch gets worn.

hehe, Is that why my "light out" light on the dashboard christmas tree comes on for a while and then goes off again for a while seemingly randomly? (or do I just have to turn in the bulbs I replace tighter into the socket or change out my suspension?)