General humidity in CAN network and computers

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General humidity in CAN network and computers

Mangoa

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Nov 14, 2014
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Barbados
I have had a Fiat Grande Punto 2009 since 3 years. After having regular problems with the CAN network and computers, it seems I have now narrowed the problem down to humidity.
When looking back at the times the car was giving problems, it seems it was always in the rainy season (I live on a tropical island with 2 seasons - dry and wet).
So now we have had a lot of rain recently and at first the problems reoccured (CAN and computer error messages, check transmission, could not read temperature, fuel cut-off not available etc. etc.) but then I bought a cover for the car (we do not have a garage of car port) and since using the cover (about 2 weeks now) the problems have not resurfaced.
Does anybody have any idea where this humidity can get into the network and computers?

Thank you for any suggestions.
 
There's a fusebox on or near the battery... but more likely are any electrical relays on the bulkhead.. or the interior fusebox.

Does your car have a sun-roof? If so, make sure the drains are not blocked (pour some water into the sunroof drain channel and make sure it runs down the drains (in each front corner). If the drains are blocked, water will leak into the car body. Clear the drains gently with a long metal rod (old wire coat hanger will do it).

When it's really wet, do the carpets feel damp .. or if you stick your hand up under the dashboard (right hand side) do the metal tubes and frames feel wet? If so, the drains under the windscreen could be blocked.

Remove the wipers and the black plastic scuttle panel and make sure that the space where the wiper motor sits isn't collecting water. As above, clear the drains in each corner (you may have one in the middle too) so that when you empty a bottle of water in it, it quickly runs out under the car.

If the windscreen is leaking (wet carpets and condensation and wet under the dash) then you might need to re-seat the windscreen (to be sure before going to the trouble and expense, just stick a load of something greasy around the seals (not Vaseline though) and see if that helps.

What you can also do is get some WD40 or water dispersant spray and give the back of the fuse box and the Body Control Module a good spray. Then place a plastic carrier back above it/around it to protect it from anything dripping on it from above.

After a week or two and some rain, pull out the plastic bag and see if it feels wet. If it's bone dry, then it's not water landing on the fuse box...

Hopefully though, you'll see a seriously blocked drain so you'll know that you've likely found/fixed the problem.


Ralf S.
 
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