2005 XC90 CEM corrosion

Discussion in 'Volvo XC90' started by Boris Mohar, Oct 6, 2009.

  1. Boris Mohar

    Boris Mohar Guest

    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?

    Boris Mohar, Oct 6, 2009
  2. Boris Mohar

    GlennK Guest

    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
    GlennK, Oct 7, 2009
  3. Boris Mohar

    James Sweet Guest

    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.
    James Sweet, Oct 7, 2009
  4. Boris Mohar

    Randy G. Guest

    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
    '90 245 Estate - '93 965 Estate
    "Shelby" & "Kate"
    Randy G., Oct 7, 2009
  5. 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 /
    Jon Robertson, Oct 20, 2009
  6. Boris Mohar

    James Sweet Guest

    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.
    James Sweet, Oct 21, 2009
  7. Boris Mohar


    Nov 28, 2010
    Likes Received:
    Thinking of replacing a CEM myself... possible, as a home garage mechanic?
    Does it need a software update to go with it?
    toddmax, Nov 28, 2010
  8. Boris Mohar


    Sep 25, 2011
    Likes Received:
    Location of CEM?

    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?

    hamishb, Sep 25, 2011
  9. Boris Mohar


    Sep 5, 2016
    Likes Received:
    Anyone have this problem with CEM? I had the water issue, corrosion on top of CEM board, and like others have stated, how crazy is it to have the one board which would be subject to water damage left uncoated like the other board below top one. Insane, but then again, Volvo was hurting and service is where the real money is made at dealerships, so this was engineered to fail, PERIOD.

    So my 05 XC90 2.5 started to cut out, buck, not start, you name it, crazy issues like many have experienced. I pulled out CEM and no, you don't have to pull wiper motor and arms out to get the CEM out like many have posted. Vehicle was starting before I cleaned CEM corrosion, but now after cleaning it with electronic specific CRC board cleaner, looks like new, even cleaned under connector which was also corroded. Felt real good until I tried to start it, started for a second, then died, no more starting, but if I wait, it will again start for a second and die. No fuel pressure at rail.

    As a side note, I had replaced fuel pump, PEM, filter, fuel pressure regulator, fuel relay, everything trying to figure this one out. The water issue tipped me off on CEM issues as I did have water on driver side floor, so any tips on what could be wrong? Hate to have to replace CEM, so any know which chip or relay on CEM can cause my symptom.

    FREE-PPV, Sep 6, 2016
  10. Boris Mohar


    Nov 21, 2023
    Likes Received:
    very much like your post, volvo must know about the water damage to CEM, but the dealership does not admit and they want to make as much money as possible on irrelevant issues (original parts: headlight and other bulbs, headlight assembly ...). I had a auto repair shop report the CEM issue to Xemodex and xemodex sent me the shipping instructions and I mailed CEM to them they sent me another reprogrammed CEM and all headlight & brake light issues were solved and problem messages disappeared. until there was hard rain and water damage came up again. must ask the auto repair shop to apply extra ceilings to prevent repeated water leakage.

    Attached Files:

    irevan, Nov 21, 2023
  11. Boris Mohar


    Nov 21, 2023
    Likes Received:
    CEM water damage probably triggered by the high pressure carwash nozzle during the free volvo dealership carwashes! not so free!
    irevan, Nov 21, 2023
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