2008 V50 2.0D won't switch off!

[chrisdc]

Lots of 'car won't start' threads but anyone ever have a situation where you turn the ignition off and the car keeps running?

Drove 100km to drop off a repair. Car turned off fine. Went to tailgate to unload...wouldn't unlock. No response from keyfob. The drivers side unlock button wouldn't unlock anything either. Put the key back in the ignition, car totally dead, no lights at all. Popped the bonnet, before I could touch anything the customer, who was standing on the driver's side, said he heard a sound from inside the car and noticed all the dash lights were on again. Car started normally after that. Tried to turn it off a few minutes later and it continued to idle, dash lights remained on. It's never done that before...ever!

Put the key back in the start position and drove to my sister's house. Warned her if I turned it off, it might not turn off and / or might not start again. Decided to park it where it didn't obstruct anything and could be easily loaded onto a flatbed if necessary. We chatted for about 15 minutes with the car idling. It then turned off fine and several hours later I drove it the 100 odd km back home again. Been too scared to drive it since as frankly, I can't afford the cost of a flatbed trip home. . Anyone have any ideas?

Perhaps I should add that approx 5 years ago, for a period of a few weeks, it would not release the ignition key. I drove it like that just covering the dash with a cloth to hide the key. Did some reading on forums of course and did partly strip the dash. One day the key just released. I spayed some Q20 into the receptacle immediately after that and it's been fine ever since.

[Clan]

Originally Posted by chrisdc

Lots of 'car won't start' threads but anyone ever have a situation where you turn the ignition off and the car keeps running?

Drove 100km to drop off a repair. Car turned off fine. Went to tailgate to unload...wouldn't unlock. No response from keyfob. The drivers side unlock button wouldn't unlock anything either. Put the key back in the ignition, car totally dead, no lights at all. Popped the bonnet, before I could touch anything the customer, who was standing on the driver's side, said he heard a sound from inside the car and noticed all the dash lights were on again. Car started normally after that. Tried to turn it off a few minutes later and it continued to idle, dash lights remained on. It's never done that before...ever!

Put the key back in the start position and drove to my sister's house. Warned her if I turned it off, it might not turn off and / or might not start again. Decided to park it where it didn't obstruct anything and could be easily loaded onto a flatbed if necessary. We chatted for about 15 minutes with the car idling. It then turned off fine and several hours later I drove it the 100 odd km back home again. Been too scared to drive it since as frankly, I can't afford the cost of a flatbed trip home. . Anyone have any ideas?

Perhaps I should add that approx 5 years ago, for a period of a few weeks, it would not release the ignition key. I drove it like that just covering the dash with a cloth to hide the key. Did some reading on forums of course and did partly strip the dash. One day the key just released. I spayed some Q20 into the receptacle immediately after that and it's been fine ever since.

Probably the pins and terminals on the CEM under the glovebox... Volvo do repair wires with crimped on silver terminals for the 6 network wires in various plugs.. Spraying contact cleaner may help but it is not a fix.

[chrisdc]

Thanks' Clan, will have a look and report back.

[chrisdc]

Ok, had a look, I see plugs going into some sort of module encased in white plastic. I'll disconnect everything and take the module out for a better look. Presumably this is best done with the battery disconnected.

In case this helps anyone, there are 2 plastic plugs that hold a bit of carpeting in place below the glovebox area. I could feel them, but only see them using a mirror. These plugs are a 2 piece design with a circular centre pin flush with the head of the plug. Just push the centre pin in as far as it will go (I used a wooden chopstick). That will allow the plug to be removed without the need for any force. Actually quite a clever design once you know how it works.

[Teddy1975]

Originally Posted by chrisdc

Presumably this is best done with the battery disconnected.

Not just best done. It is vital that this is done with the battery disconnected as you do not want to risk frying the CEM.

[chrisdc]

Right....so the problem was eventually solved by tightening the front battery terminal!

I did replace the battery myself several years back. Forty odd years ago, as a teenager with his first car, I remember an auto electrician warning me not to over tighten battery clamps. I think at the time my battery posts had developed 'waists' and consequently it was hard to get the clamps off.

My V50 has an odd battery clamp fastening system whereby the bolt that secures the clamp comes up vertically through the clamp as opposed to one that goes through the clamp horizontally. My guess is the vertical system is less efficient and requires a lot more torgue on the nut to get it tight. The front clamp has heavy cable hanging off it at a 90 degree angle which also tends to 'load' the clamp. When this problem first appeared, the very first thing I did was try and wiggle the battery cables. I didn't see any movement and assumed they were tight. I guess this is a good example of 'confirmation bias' in action.

Oh, the breakthrough came after a few bulbs blew. Sometimes I'd notice the headlights flickering. Also the reverse lights and even the lights on the display in the waterfall. I guess every time the battery clamp lost contact, the alternator load was effectively considerably reduced, resulting in increased voltage.