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CEM related issues: My diary of ongoing findings...

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Old Apr 15th, 2020, 14:39   #11
lockstock
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Originally Posted by poiuytre111 View Post
I have had this problem on my C70 but am currently "in remission". If and when it comes back I will be very tempted to bypass the plugs altogether with soldered wire bridges, if indeed I am able to identify just 6 wires (3x twisted pairs) carrying the digital comms.
well, if you screw this up at all, and the resistance is out of range then it won't help.
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Old Apr 30th, 2020, 21:56   #12
Nick C30V50V40
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I'm going to chuck this in here as it may help you and a few others, I too have a V50, mines a 2.0D on a 56 plate. Very similar issues to yours, sudden lack of power, brake and airbag warning lights plus 20 or 30 fault codes all unrelated. I looked at the forums and saw that people had been having similar problems so I took the electrics apart.
I stripped down the CEM and re-soldered every connection that looked less than perfect and re installed it, went ok for a while but came back after a couple of weeks. Wifey came back moaning about the power loss so I went out started the car....... nothing all fine? I scanned it again, loads of codes relating to communication issues between different modules?
So a real ghost in the machine scenario, I have studied the wiring diagram and really cant see a link between the different affected systems outside the CAN BUS ring with the CEM being the junction. I wanted to eliminate faults caused by noise so I have attached ferrite cores around the coms plug wires.
Its been 8 months now and all is well.... perhaps it was that simple who knows, so far it's worked for me.
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Old May 2nd, 2020, 20:44   #13
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I'm not tech savvy enough to go further into the ins and outs of the Can network and such like and even the thought of re-soldering pins is beyond me however, said V50 is still running flawlessly with no relapses since the last strip / clean / emery cloth session back in January and it's been given trial by wife, flood, ice and toddler and has been find. Granted, that's great in some ways but in others, it's still a niggling fault that may / may not be cured and indeed could return at any time... but until it does, then it's really a case of you can't fix what ain't broke.
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Old May 4th, 2020, 13:56   #14
Nick C30V50V40
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Exactly my point, I tried all the stripping down and soldering bit and it made no difference, in the end a couple of £1.50 clip on ferrite core seem to have done the trick.
Still glad it's working for you, nothing worse than a car you can't trust.
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Old May 4th, 2020, 14:50   #15
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Originally Posted by poiuytre111 View Post
I have had this problem on my C70 but am currently "in remission". If and when it comes back I will be very tempted to bypass the plugs altogether with soldered wire bridges, if indeed I am able to identify just 6 wires (3x twisted pairs) carrying the digital comms.
This problem is well known now for the last 10+ years it needs new female wiring terminals on the 6 network wires which go into the CEM plugs they loose their grip on the male pins . Volvo sell them already crimped on to a piece of wire you solder in after cutting the old one off,
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Old Oct 22nd, 2020, 21:56   #16
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I feel your pain with this CEM issue,I parked mines up and got herself a GTI golf,as she flat refused to drive the motor after it wouldnt start and conked out on her a couple of times,your Mrs must be very understanding,still driving it,haha,,I have just put it back on the road as a workhorse for myself after its lay in dry dock for about 18 months,,if I didnt like the car so much it would have been long gone,,its a V50 Sport,,lots of usefull information there for if the problem rears its ugly head again,,I knew it was a CEM issue,but never got around to dealing with it,,thankyou for informative posts,,
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Old Oct 23rd, 2020, 12:19   #17
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On the other hand each time you take them out it scrapes them clean , it is a damp area down there with passenger's wet feet . The vast majority don't have any problems but unfortunate a few do , but it is known now what is going on👍

Hi CLAN, guess what problem I have on my 07 V50 2.0d 🙄

Someone I know through a hobby has suggested tracking you down, he said you can advise on the plugs needed, I see you mention digital cables above, do I go and see the local Volvo dealer or is this something I find on the web. Many thanks
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Old Oct 23rd, 2020, 16:25   #18
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I may live to regret this but the "don't bend the pins / rubbing the tin off will make it worse" logic does make sense but we're now several months and another 12,000 miles further down the line having done exactly that and the car has been flawless... so whilst I'm sure there are "permanent" fixes, until it develops said issues again then I'll just keep on going whilst avoiding the CEM like the plague in case I disturb something and it has a meltdown again.
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Old Oct 23rd, 2020, 16:35   #19
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I may live to regret this but the "don't bend the pins / rubbing the tin off will make it worse" logic does make sense but we're now several months and another 12,000 miles further down the line having done exactly that and the car has been flawless... so whilst I'm sure there are "permanent" fixes, until it develops said issues again then I'll just keep on going whilst avoiding the CEM like the plague in case I disturb something and it has a meltdown again.
Well.. try submitting the vehicle to the extremes of cold and heat and vibration that it has to survive. Put all three together and that's when contact pressure really makes a difference.

If you avoid those extremes then a patch job can survive a long long time
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Old Oct 24th, 2020, 01:38   #20
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I may live to regret this but the "don't bend the pins / rubbing the tin off will make it worse" logic does make sense but we're now several months and another 12,000 miles further down the line having done exactly that and the car has been flawless... so whilst I'm sure there are "permanent" fixes, until it develops said issues again then I'll just keep on going whilst avoiding the CEM like the plague in case I disturb something and it has a meltdown again.
"trial by toddler" should test that for you
or next time you need to change the pollen filter

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Hi CLAN, guess what problem I have on my 07 V50 2.0d 🙄

Someone I know through a hobby has suggested tracking you down, he said you can advise on the plugs needed, I see you mention digital cables above, do I go and see the local Volvo dealer or is this something I find on the web. Many thanks
that'd be my fault there then.
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Last edited by andy_d; Oct 24th, 2020 at 01:41.
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