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Re: Why a computer in cluster (was: Gremlins in Tank)



John, that is interesting, educated speculation, and sounds plausible.  So
if fuel gauge circuits need to be so complicated now, for the reasons
you mention, I'm just curious:  Do other makes of cars have similar
circuits and problems?

Scott Miller
GGC BMW CCA #44977

>Date: Wed, 23 Sep 1998 21:47:05 +0200 (MEST)
>From: John Firestone <john.firestone@domain.elided>
>Subject: Why a computer in cluster (was: Gremlins in Tank)
>
>Scott Miller writes:
>> 
>> New BMW gas gauge:  Sender in tank, wires to computer, wires from
>> computer, gauge in dash.
>> 
>> Question:  Why does the gas gauge need a computer?
>
>Several reasons I expect:
>
>   - to detect faults in the fuel sender signal (shorts to ground, to +12,
>     intermittent connections, faulty senders and nonsensical readings);
>
>   - to pinpoint problems with the fuel gauge via the cluster system test;
>
>   - to monitor the fuel senders via the workshop DIS computer;
>
>   - to simplify the low fuel warning and make it more repeatable;
>
>   - to simplify the OBC and insure its displayed RANGE is consistent
>     with the instrument cluster;
>
>   - to allow easy, software downloads to the cluster (coding data) that 
>     adjust for differences among models or changes over different 
>     model years (e.g. a different tank size).
>
>- -John
>'96 318is
>john.firestone@domain.elided

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