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1995 540i - Alarm, Key, runs but no OBC,

Discussion in 'E34 (1989-1995)' started by stuarts540i, Dec 15, 2009.

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    stuarts540i guest

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    1995 540i, 6 speed. This is the best BMW I have ever owned and driven. I bought it in 1998 with 49,000 miles. I now have 214,000 miles and it runs like top.

    I live and work in Dayton, Ohio. Awhile back, maybe 10,000 miles back, I left my 1995 540i at the Louisville, KY airport while I took a trip to Florida. At the Louisville airport I locked the car with the button on the 3 button ignition keypad. Two days later when I returned from Florida the temperature was 20 degrees at the Louisville parking lot. I was nervous about unlocking the car using the button on my key because I had fear the battery in the key might have been low. I therefore decided I would open the door by inserting and turning the key in the door lock. When I did this, the alarm sounded and I could not get the alarm stopped by inserting the key into the ignition. I was able to get the alarm stopped holding one of the buttons on the key down. I then tried to start the car. The car started and ran for about 20 seconds before the engine stopped. I went through the same scenario; close the door, lock the car by turning key in door lock, unlock with key in door lock, each time the alarm sounds, push key button to stop alarm, insert key in ignition switch and turn the key to start car, now each time the engine would turn over but not fire or start.

    I called AAA and they picked up the car. I rode the rollback to the BMW dealer in Louisville with my car. I explained the problem to the service writer. The dealer worked on the car for about 4 hours. I could watch through the service window, a couple of different personnel consulting over my car in the shop bay. Finally the service manager told me, "It will take more than a day to solve and correct the problem, so we have unplugged the O.B.C under the rear seat so you can drive back to your home in Dayton, Ohio. "In Dayton you can take it to a BMW dealer there and they will have the time to properly diagnose and repair you system."

    Because the car runs so well I have procrastinated. Now I am ready to get the system fixed so I can have the use of the computer, and so I won't have to insert the key in the door lock to lock and unlock the car. Everything seems to work fine, except I don't have the computer on the dash, and the buttons of the key do nothing. I would like to correct the problem, but need to learn from anyone with this experience and recommendations where to start.

    Thank you, Stuart in Dayton
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    I think its possible your battery may have been damaged by extreme cold

    This will likely affect OBC operation. The extreme cold would have likely caused a drop in the battery voltage in the OBC.

    First thing I would do is have the battery checked out. Take it to autozone and have them do a full diagnostic on the battery.

    As I own a 750iL, I have learned the secret for resetting a forgotten or malfunctioning alarm lock code, but out of concern for other E32 and E34 owners, I will not post it here. You can email me and I will describe the process.

    The next thing I would check if the battery checks out is have your alarm module checked out by the dealer.

    Last but not least, this issue may have toasted your OBC. Not sure if BMW still supplies replacements, but the OBC IV still abounds in lots and lots of E32 and E34 vehicles.
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