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BMW E38 7 Series 1995-2001 (735i, 740i/iL, 750i/iL) e38 Service light, how it works?


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Last Post: Dec 26, 2010 1:51 AM Last Post By: wolverine
Bemaristi

Posts: 2
Registered: 06/21/08
e38 Service light, how it works?
Posted: Feb 25, 2010 6:27 PM
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Sorry about bad english.

A question about e38 1995-2001 SII(service lights) calculation. How does the SII control unit calculate a next service time?

This is quote from the Bentley's e39 service manual:

For the 1997 and later 5 series, BMW introduced an oil change interval based on fuel consumption. The advantages of this system is:


* Fuel consumption is an accurate method of determining engine load and the need for service


* The prosessing electronics are simple


* Reseting of indicator before the scheduled time will not affect the time to the next service


The SII is programmed to measure a set volume of consumed fuel. This volume varies between models, dependent on vehicle and engine sizes. The SII control unit receives a signal from the engine control module (ECM) when the vehicle is in use. As 20% of the programmed fuel volume is consumed, one of the green LEDs will go out. Each successive 20% of fuel consumption will cause the next LED to go out until 100% of the measured volume has been consumed. At this point the yellow LED will come on, indicating that service is due. When 108% of the measured volume has been consumed, the red LED will illuminate, indicating that service is overdue.

Is this method used from the beginning of production of the e38's, or has it changed at 1997? And if so, how was the service interval calculated before? The instrument clusters looks like same over the production years...And same cluster was used in e39. Is the 1997 somekind magic year?

wolverine

Posts: 6
Registered: 12/26/10
Re: e38 Service light, how it works?
Posted: Dec 26, 2010 1:51 AM   in response to: Bemaristi in response to: Bemaristi
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it responds to gallons of fuel consumed rather than pure mileage which is good because "city" stop and go type driving is harder on the car and components than smooth effiecent highway driving

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