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Old 11-20-2012, 12:59 PM
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acoste acoste is offline
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Location: California
Join Date: Nov 2011
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Mein Auto: 2010 550i MT
Originally Posted by neonphire8604 View Post
Ok, I understand what you are saying. I have been trying to watch for rpm on my scan tool while cranking but it loses communication a couple seconds in. should I be checking for network issues like module powers/grounds and can lines?
You might wanna check the ground for the engine control module (on the engine side under the right cabin air filter - visible) but I don't think this is the issue. Loosing communication during cranking is not a surprise, that happens because the supply voltage drops for a while.

I would check the battery first even if you think it's fine. Then cables, connections, tightening nuts.
Get another car with strong battery and jump start your car on the top of the engine. Also the negative cable has to be connected to the engine block.
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