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    Re: BMW 5 320d E60/61 blower resistor location Archived Message

    Posted by Sean Mc Gettigan on January 20, 2010, 10:52 pm, in reply to "Re: BMW 5 320d E60/61 blower resistor location"

    Hi Matthew, start with an easy question why dont you?

    The honest answer is you'd need a software engineeer to answer the question properly but I can share my views and experiance's with you if it helps any.

    I'm seeing more and more cars with software updates as part of the fix or as the complete fix. The easier one's to explain are engine management related issues so I'll start there

    Example 1
    BMW E46 320d
    Very intermittant non start with no fault codes.
    Update the software and the next time the fault occures a fault is stored for Crank or Cam sensor circuits/sync.
    In simple terms when the original software was developed it was not designed to set a fault code when either one of the CAS/CAM signals were missing and the engine was cranked over, it would only fire the engine when both were present and correct. The new software however will set a code when one signal is present without the other on crank.

    Example 2
    BMW E60/61
    Battery drain overnight.
    Some basic testing shows one/some of the modules is/are not shutting down. Run a CIP and update the car as required and now the module shuts down as normal and the drain is gone.

    Example 3
    BMW E60/61
    One of the windows opens itself at random during the night.
    Run a CIP update and hey presto the fault is gone


    The first example is when the software is part of the cure and makes sense to the way we think as techs but the last two the software IS the fix and harder for us to understand.

    There are a few things I've noticed in these situations however and the most common is low/flat batteries(car sales) and jump starts.
    Each system and sub-system is woken up by remote/acc/ign on and as the software begins to do its thing the engine is cranked and there is a voltage/current surge followed by a low/no power supply so the software gets corrupted by this and refuses to carry out its job propely anymore!

    We've also got to remember that the software has been writen originally by a man/woman and no matter how hard we try we all make mistakes.
    Its sometimes not possible to think of, and test every possible senario when there are more and more ECUs being networked together with differant levels of software,some glitches just slip through and don't show up until a certain set of circumstances are met later in the cars life.

    Here's one to chew on,
    You have a virus on your pc which is connected to your i-pod to load music in software form complete with a nice virus. Then the i-pod is connected to the car to share its new present with the car which has fifty ECUs all networked together

    Back to the heater control issue, I think of it in this way,
    The user input to the HVAC control panel for blower control is translated by SOFTWARE into a digital signal to be transferred by another SOFTWARE program onto the LIN/CAN bus which is then received by the blower speed control module read by SOFTWARE and transferred back into a command to operate the blower as it reads the request.
    If there is a software issue in any of the above SOFTWARE controls then the requested command is not carried out or misunderstood by the end user and the blower does not do what you want it to.

    We've got to think differantly about problems on these newer generation cars, very little is hard wired direct, everything is networked and software controlled in at least two ECUs.

    The above examples are BMW in relation to the help request regarding a BMW but I see the same on VAG's, Vauxhall's, Volvo's, Renaults, Jaguars, Porsches, Land Rovers etc

    I found out the hard way, dont run yourself in circles looking for a fault you cant find, UPDATE THE SOFTWARE FIRST then IF you still have a fault start your diagnosis with a clean slate.

    Hope this makes some sense
    Sean

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