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Thread: E34 economy/instant MPG gauge problem

  1. #1
    Join Date
    May 2018
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    1995 BMW E34 525TDS

    E34 economy/instant MPG gauge problem

    My economy gauge bounces up all the way to +30 liters the moment I start the car.
    When I start moving it drops to 0 and stays there,no metter how much I depress the gas pedal.
    Can someone tell me how this gauge works? What connections do I need to check?
    I already tried replacing the cluster,but the problem remained.
    SjtMCLP.jpg
    Last edited by General984; 02-01-2019 at 08:32 AM.

  2. #2
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    11/88 E32 750iL+98 E36M3
    when you start the car and do not move, then it will be on your EURO model maximum reading, because it should show liters/100km, but as you do not move, it shows max. reading. Copied from the E36 owners manual:
    The energy control indicates the current fuel consumption in mpg (in liters per 100 km on Canadian + EURO vehicles). When the vehicle is stationary, the needle returns to zero (maximum reading on Canadian + EURO models).

    But when you start moving, it should start showing the consumption. I would check the speed sensor on the final drive/differential, maybe that does not send a clear signal to the cluster, where the signal is processed http://www.bmwe34.net/E34main/Mainte...eed_sensor.htm
    Shogun tricks and tips for the E32 series are HERE!

  3. #3
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    Speed gauge works completely fine,so I assume sensor is working..Anything else?

  4. #4
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    check on the cluster if the the connector X271 grey has good contact, pin 8 and 10 are the speed signal http://www.e32-schrauber.de/bmw/date...egung-x271.pdf
    Shogun tricks and tips for the E32 series are HERE!

  5. #5
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    Can I test that with test light?

  6. #6
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    Maybe a electr. expert can tell you, what kind of signal you receive there respect. can measure.
    Shogun tricks and tips for the E32 series are HERE!

  7. #7
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    '73 E9, '94 E34, '02 E46
    Rotate the wheel slowly and use a multimeter set to volts on one wire at a time and ground. The sensor sends a pulse that the multimeter will detect. An analog meter is more useful in this situation (shows pulses better) than a digital multimeter.
    Charlie

    Your mission, should you decide to accept it, is to add value to these threads, either by pictures or by descriptions, so the next person with the same or similar problem stands on your shoulders.

  8. #8
    Join Date
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    BMW E34 528i sedan
    Hello, I have been having absolutely the same problem since I bought my car. Were you able to resolve somehow it or you gave up? ��

  9. #9
    Join Date
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    E34
    İ have the same problem and i can't figure it Out
    Did you fix it by any chance

  10. #10
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    did you check the speed sensor on the diff? http://www.bmwe34.net/E34main/Mainte...eed_sensor.htm
    the economy control display is actuated by a microprocessor. The road speed signal from the rear axle reed contact and the injection signal TI serve as basic information for this purpose. The TI signal comes from the DME control unit, is processed in the instrument cluster and delivered to the EC. In addition, at idle speed (car stopped) the indicator will dis-appear under a mask and no longer point to maximum fuel consumption as in the past.
    Excerpt from instrument cluster/check control training reference book, information status 01/1989
    Shogun tricks and tips for the E32 series are HERE!

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