Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!

2007 750i E65 BMW intermittent no start.

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5 years 3 months ago #25223 by Paul6004
Customer states that when it doesn't start ALL the dash lights come on. After leaving it for a while it will start with only a few of the dash lights coming on..
There were the usual 30 or 40 fault codes in the 54 modules the Autel MD805 located but nothing significant. Any ideas on what it could be since it isn't playing
up for me?
{I did pry the key apart and check the battery at 3.3v]

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5 years 3 months ago - 5 years 3 months ago #25230 by Andy.MacFadyen
Can you communicate with system when it misbehaves --- particularly the IPK, Engine Management , Body Computer, Light Switch Module and EWS.
My first move would be to check the car battery voltage and battery connections , check the voltage both by direct measurement and scan data.
The part of the fob that deals with immobilization is not powered by the fob battery it is a transponder chip (in BMW usually a weird coffin shape) not mounted in the circuit board but in the fob shell. To check the immobilizer transponder chip most pro-level scantools will tell identify the key in use and show if it is a valid key authorized to start the car.

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



Last edit: 5 years 3 months ago by Andy.MacFadyen.

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5 years 3 months ago #25249 by Jay2034
Bmw is known for the ibs sensor to go bad and give similar systems. It's the intelligent battery sensor located at the battery on the negative post terminal. If ur sysmtoms happen go unplug and see if it starts up. Had a couple of those give me a hard time. But when it does happen see if u have communication like Andy is saying and if u unplug and gain communication back u found ur fault. Just a little tip.

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5 years 3 months ago #25257 by Andy.MacFadyen
BMW Irritable battery Syndrome was where I was headed, the part has been upgraded by BMW several times. It passes information on battery state of charge, voltage, load and starter motor current to the engine computer. Check for signs of water ingress in the area. You can disconnect the com connection for testing --- not unknown or owners to leave it permanently disconnected

If the com connection is simply disconnected , the engine will run and be perfectly usable but there are a couple of downsides idle speed will be slightly higher as an anti-stall measure and the alternator will charge at default higher rate which may have some effect on battery life, and fuel consumption and emissions.

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



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5 years 3 months ago #25259 by Jay2034
Very well put andy

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5 years 3 months ago #25325 by Andy.MacFadyen
Honda now are using a very similar system equally troublesome
autoweek.com/article/recalls/over-1-mill...battery-sensor-blame

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



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