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

[Clan]

Originally Posted by aquacultureman

Thank you very much Clan. Stupid question - if I order 6 terminals from Volvo, will they already be twisted into their constituent pairs, or is that something I need to do? I notice that Skandix supplies them as single wires, and am vaguely aware of the electromagnetic interference reason for twisting.

they come with 6 inches of wire already crimped to a terminal just solder them together . a short distance not twisted is ok .

[aquacultureman]

Originally Posted by Clan

they come with 6 inches of wire already crimped to a terminal just solder them together . a short distance not twisted is ok .

Thanks. Thats a great help.

[aquacultureman]

Originally Posted by aquacultureman

Thanks. Thats a great help.

@Clan: Going to also check the earth leads to the CEM also. Would you know what coloured plugs the earth wires are on? There are are 2 - both black (A:28 and A14). sorry mate - but I'm up the poles with this issue.

[wmitchell]

Originally Posted by Stew1099

I ended up purchasing a recon CEM from Volvo diagnostic. I gave them the old one and they transferred the software onto the recon CEM in 45 mins. The CEM has been back on over 6 weeks now with no issues. The old CEM showed no sign of corrosion and the "clean the pins and spray the connectors" worked a few times but I was getting fed up with the "brake failure message" especially on the motorway at high speed. Fingers crossed I'm free of any more CEM issues!

Been a few years, did the recon CEM hold up? getting similar aforementioned issues (sudden loss of power, anti skid service warning, sudden cutting out with 'brake failure, stop safely' message, etc) for a while on my V50, managed to sort a few issues by cleaning CEM contacts and pins with contact cleaner, but still gettting issues relating to sudden loss of power for a couple seconds, related (apparently) to the accelerator pedal (error codes p1577 and p0122).

Rang my local volvo specialist who recommended a 'new' cloned CEM from Volvo Diagnostic, just a bit wary of parting with a load of money for one hearing some similar testimonies, likewise I'm reliant on my car for work, which is out in the sticks a bit so will be a bit of a bind trying to commute there without it while I wait for the CEM to come back.

[Clan]

Originally Posted by wmitchell

Been a few years, did the recon CEM hold up? getting similar aforementioned issues (sudden loss of power, anti skid service warning, sudden cutting out with 'brake failure, stop safely' message, etc) for a while on my V50, managed to sort a few issues by cleaning CEM contacts and pins with contact cleaner, but still gettting issues relating to sudden loss of power for a couple seconds, related (apparently) to the accelerator pedal (error codes p1577 and p0122).

Rang my local volvo specialist who recommended a 'new' cloned CEM from Volvo Diagnostic, just a bit wary of parting with a load of money for one hearing some similar testimonies, likewise I'm reliant on my car for work, which is out in the sticks a bit so will be a bit of a bind trying to commute there without it while I wait for the CEM to come back.

cleaning the pins is not a reliable way of dealing with the problem the 3 pairs of network wires which go to and from the CEM need volvo repair terminal wires, they loose their spring tension. The dealers have been fixing these for 15 years now... you may need to renew the throttle pedal terminals too , It is NEVER the throttle pedal itself at fault.

[Newman2002]

Clan,
My son's car is having a lot of similar symptoms, and is currently not running, nothing lights up on the dash, key won't turn off and come out, etc after an episode of the wipers coming on by themselves and other issues. I read already about the replacement terminals at the CEM and accelerator pedal, but I'm also seeing several SRS codes for CAN signal missing. 012D, 012A,0129. Is this something I should investigate also? I'm waiting on a coworker to come unpin the CEM connectors for me, I need new bifocals and can't quite focus well enough on the connector to do it myself without fear of breaking something lol

[BBA]

Hello ,sorry to writing here, apart of all common lights and messages on the dash do you suffer imobilaiser issue as well ? Whit this 6 wiring I was check and clean CEM and connectors all plugs looks seat tight but car can run ok for a day or two or can give up after 30 min and not start for one and half day . As imobilaiser not letting to start no mater what key I put in ( have two keys)
Volvo v50 2008 2.0d Thank you for all information what I read in this thread .
( Pardon for my English writing )

[BBA]

Originally Posted by Clan

cleaning the pins is not a reliable way of dealing with the problem the 3 pairs of network wires which go to and from the CEM need volvo repair terminal wires, they loose their spring tension. The dealers have been fixing these for 15 years now... you may need to renew the throttle pedal terminals too , It is NEVER the throttle pedal itself at fault.

Hello ,sorry to writing here, apart of all common lights and messages on the dash do you suffer imobilaiser issue as well ? Whit this 6 wiring I was check and clean CEM and connectors all plugs looks seat tight but car can run ok for a day or two or can give up after 30 min and not start for one and half day . As imobilaiser not letting to start no mater what key I put in ( have two keys)
Volvo v50 2008 2.0d Thank you for all information what I read in this thread .
( Pardon for my English writing )

[lymingtonbob]

Hi, I am experiencing all the intermittent faults that seam typical of this problem. My suspicion is that there are dry solder joints where the connection block attatches to the mother board inside the CEM. All the unplugging and cleaning is causing these joints to temporarily reconnect, but the problem will only continue to get worse as the bad joints will not repair themselves. The only solution seams to be to replace the CEM with a remanufactured unit and have the software cloned. The only other thing I have noticed is that when I check and clear the fault codes after an episode there is a U0126 error "lost communcation with steering angle sensor". If anyone knows which connector block links this sensor to the CEM it might locate the dry joint(s). Any comments would be welcome. Bob

[pinballdave]

Originally Posted by lymingtonbob

The only other thing I have noticed is that when I check and clear the fault codes after an episode there is a U0126 error "lost communcation with steering angle sensor". If anyone knows which connector block links this sensor to the CEM it might locate the dry joint(s).

The steering angle sensor is on the high speed CAN bus, and is one of the typical faults caused by the connector terminals issue. I think these ones are the F14 and F16 pair as detailed in the posts from Clan above.

The solder joints on these connectors are usually good, and the connector housings and locking system are well designed putting little stress onto the connector pins and solder joints. The wiring harness terminals are the main weakness in this area (provided there's not been any corrosion caused by water ingress!).