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Hazards randomly come on..

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Old Nov 19th, 2020, 14:15   #1
JohnnyDMonic
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Default Hazards randomly come on..

The hazards on my 2010 V50 keep randomly coming on.

It seems like the most common answer is that the switch is faulty so I took mine out, completely stripped it down, blew the dust out the switch with compressed air, then squirted some fader lube in it and worked it in and out a load of times.

Whilst it was all apart, I checked everything with the multimeter and I can see the switch operating perfectly. The resistance of the little bulb inside reads 22 Ohms, which seems a little low assuming it operates at 12v (would mean it draws over half an Amp), but I digress..

So I think to myself everything seems fine with the switch, I'll plug it back in and see what happens. As soon as the plug made contact with the connector in the car the hazards immediately started flashing. Pressing the button had no effect. Unplug switch, nothing happens. Plug switch back in and the hazards immediately stop flashing. Pressing the button still has no effect.

It seems that the very act of plugging the switch in, makes the car think the button has been pressed. Which would imply to me that the switch connections have somehow become permanently connected together, but this is not the case as I have verified with the multimeter.

The next thing I thought was maybe the bulb was somehow having an adverse effect on the whole system so I removed it (in just unscrews really easily), but this didn't change the behaviour at all, it was exactly the same.

Has anyone ever seen this before, or could anyone offer an explaination of what's going on? I'm baffled.

Cheers,

John.
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Old Nov 20th, 2020, 02:53   #2
ukojesita
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Has the pollen filter been replaced recently; hence CEM disturbed?

The reason I am asking is that my V50, 2012 suffers from electrical breakdown circa every six months (due to well documented design flaw in the connection of the CEM to the rest of the car). The latest manifestation of the poor connection in my car was fluctuating fuel gauge. However, I also had hazard lights misbehaving, wipers on, engine service message, brakes failure message, you name it.

When I connected the car to VIDA, I would always get several COM errors.
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Old Nov 20th, 2020, 13:32   #3
Clan
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Default

Quote:
Originally Posted by JohnnyDMonic View Post
The hazards on my 2010 V50 keep randomly coming on.

It seems like the most common answer is that the switch is faulty so I took mine out, completely stripped it down, blew the dust out the switch with compressed air, then squirted some fader lube in it and worked it in and out a load of times.

Whilst it was all apart, I checked everything with the multimeter and I can see the switch operating perfectly. The resistance of the little bulb inside reads 22 Ohms, which seems a little low assuming it operates at 12v (would mean it draws over half an Amp), but I digress..

So I think to myself everything seems fine with the switch, I'll plug it back in and see what happens. As soon as the plug made contact with the connector in the car the hazards immediately started flashing. Pressing the button had no effect. Unplug switch, nothing happens. Plug switch back in and the hazards immediately stop flashing. Pressing the button still has no effect.

It seems that the very act of plugging the switch in, makes the car think the button has been pressed. Which would imply to me that the switch connections have somehow become permanently connected together, but this is not the case as I have verified with the multimeter.

The next thing I thought was maybe the bulb was somehow having an adverse effect on the whole system so I removed it (in just unscrews really easily), but this didn't change the behaviour at all, it was exactly the same.

Has anyone ever seen this before, or could anyone offer an explaination of what's going on? I'm baffled.

Cheers,

John.
The hazzard switch does not control the lights , all it does is send a signal to the main computer under the glovebox which then activates the hazzard lights ..
Have you any other unusual function happening?
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Old Nov 20th, 2020, 21:37   #4
JohnnyDMonic
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Quote:
Originally Posted by ukojesita View Post
Has the pollen filter been replaced recently; hence CEM disturbed?

The reason I am asking is that my V50, 2012 suffers from electrical breakdown circa every six months (due to well documented design flaw in the connection of the CEM to the rest of the car). The latest manifestation of the poor connection in my car was fluctuating fuel gauge. However, I also had hazard lights misbehaving, wipers on, engine service message, brakes failure message, you name it.

When I connected the car to VIDA, I would always get several COM errors.
Interesting you should say that. It was serviced recently and they probably did the pollen filter. I had a couple of "Engine System Service Required" messages since then which seem to have just gone away after a few hours, but they were accompanied by a drastic reduction in engine power too so may not be related. I will have a look though, thanks.
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Old Nov 20th, 2020, 21:42   #5
JohnnyDMonic
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Originally Posted by Clan View Post
The hazzard switch does not control the lights , all it does is send a signal to the main computer under the glovebox which then activates the hazzard lights ..
Have you any other unusual function happening?
Yeah I get how it works. The button is just a momentary switch which is detected by a micro-controller somewhere.

What I can't fathom is why the switch works perfectly when tested with a multimeter, but not when plugged into the car.

Apart from the error message on the dash I mentioned in my previous post, everything else on the car works perfectly.
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Old Dec 12th, 2021, 19:52   #6
ByToutatis
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Hi
Did you manage to resolve this? I have exactly this problem now - curious what I can do about it!
Many thanks
Graham
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Old Dec 12th, 2021, 20:03   #7
JohnnyDMonic
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Yes I did manage to resolve it. I took the car for an MOT and the switch was still playing up so the garage just ordered and fitted a new switch from volvo for about £20. No problems since then.

Still can't understand why it tested fine on the multimeter, but I haven't got time/headspace to worry about that now lol.
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Old Dec 12th, 2021, 20:21   #8
ByToutatis
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Great - will take it off to the garage to get that sorted then!
Thanks for the quick reply!
Graham
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