2005 XC90 CEM corrosion

From 2005 XC90 CEM

A Volvo mechanic showed me this bit of insanity. The CEM1 circuit board
sits on top of CEM3 circuit board and they are soldered to each other via
header pins. CEM3 is conformably coated but CEM1 is not. The difference due
to exposure to elements is obvious. What possessed Volvo to protect one
board and not the other?

http://www.viatrack.ca/Misc/CEM1.JPG
http://www.viatrack.ca/Misc/CEM3.JPG

--

Boris Mohar

On 10/6/2009 2:32 PM, Boris Mohar wrote:
> From 2005 XC90 CEM
>
> A Volvo mechanic showed me this bit of insanity. The CEM1 circuit board
> sits on top of CEM3 circuit board and they are soldered to each other via
> header pins. CEM3 is conformably coated but CEM1 is not. The difference due
> to exposure to elements is obvious. What possessed Volvo to protect one
> board and not the other?
>
> http://www.viatrack.ca/Misc/CEM1.JPG
> http://www.viatrack.ca/Misc/CEM3.JPG
>
The problem is water leaking in through the top cover on the cowl that
was not correctly sealed @ the factory. When I replace the CEM I use a
good glue to make sure that there is no water egresses in the passenger
compartment near the CEM
Glenn K
Certified Volvo Technician 2008
ASE Certified Technician 2008

Boris Mohar wrote:
> From 2005 XC90 CEM
>
> A Volvo mechanic showed me this bit of insanity. The CEM1 circuit board
> sits on top of CEM3 circuit board and they are soldered to each other via
> header pins. CEM3 is conformably coated but CEM1 is not. The difference due
> to exposure to elements is obvious. What possessed Volvo to protect one
> board and not the other?
>
> http://www.viatrack.ca/Misc/CEM1.JPG
> http://www.viatrack.ca/Misc/CEM3.JPG
>


That is strange.

The corroded one looks repairable though, I've fixed pinball machine CPU
boards that were in much worse shape from the memory backup battery
leaking all over them. Vinegar wash followed by a careful scrub with a
brass bristled brush can work wonders.

Boris Mohar <borism_void_@sympatico.ca> wrote:

>
>From 2005 XC90 CEM
>
> A Volvo mechanic showed me this bit of insanity. The CEM1 circuit board
>sits on top of CEM3 circuit board and they are soldered to each other via
>header pins. CEM3 is conformably coated but CEM1 is not. The difference due
>to exposure to elements is obvious. What possessed Volvo to protect one
>board and not the other?
>
>http://www.viatrack.ca/Misc/CEM1.JPG
>http://www.viatrack.ca/Misc/CEM3.JPG

I would head over to the local electronics store and pick up some
products meant for such application- a board cleaner and there should
also be a spray available to seal the surface from moisture. be sure
to tell them that it is an assembled component and not just a circuit
board. I would not spray on the components (put a bit of painter's
tape on them). They may need air circulation for cooling. If nothing
like that is available, use WD-40 and a toothbrush. That should also
help keep the moisture problem at bay.
__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

I have seen a GM car with zinc blocks attached to the body to act as
sacrificial anodes I am interested in what Mr Sweet or Mr Klien think of
this seriously /
"James Sweet" <(E-Mail Removed)> wrote in message
news:hah14d$sp2$(E-Mail Removed)...
> Boris Mohar wrote:
>> From 2005 XC90 CEM A Volvo mechanic showed me this bit of insanity. The
>> CEM1 circuit board
>> sits on top of CEM3 circuit board and they are soldered to each other
>> via
>> header pins. CEM3 is conformably coated but CEM1 is not. The difference
>> due
>> to exposure to elements is obvious. What possessed Volvo to protect one
>> board and not the other?
>>
>> http://www.viatrack.ca/Misc/CEM1.JPG
>> http://www.viatrack.ca/Misc/CEM3.JPG
>>
>
>
> That is strange.
>
> The corroded one looks repairable though, I've fixed pinball machine CPU
> boards that were in much worse shape from the memory backup battery
> leaking all over them. Vinegar wash followed by a careful scrub with a
> brass bristled brush can work wonders.

Jon Robertson wrote:
> I have seen a GM car with zinc blocks attached to the body to act as
> sacrificial anodes I am interested in what Mr Sweet or Mr Klien think of
> this seriously /


Well it ought to reduce body corrosion, but I seriously doubt it would
have any effect on the inside of electronics. There exist potential
differences due to power supplied to the circuit and whatever is more
positive will be the anode either way.

Zinc is often used on boats, and works well to prevent corrosion of
metal hardware.

Thinking of replacing a CEM myself... possible, as a home garage mechanic?
Does it need a software update to go with it?

I have a 2003 XC90 T5 AWD (right hand drive).

My CEM is playing up - classic symptoms of cutting out whilst driving (seems to only occur on long trips when its warmer. Stopping for half an hour seems to fix it).

So looking at DIY replacement, or at least ordering some parts on line and taking to my dealer.

Where is the CEM located, and how does the water get in?

Where to buy on-line? swedishautoparts dot com?

Thanks
Hamish