How's the vacuum switch work?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by bike-maker, Jun 8, 2011.

  1. bike-maker

    bike-maker Full Access Member

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    So I want to hook up an idiot light in my dash to my vaccum switch on the fuel filter housing. The truck is originally a gasser, so there is no wiring for it. How does the switch actually function? My assumption is that when it senses a vacuum, the electrical terminal just has continuity to ground. This sound correct? Makes for an easy hook up if that's the case.
     
  2. jim x 3

    jim x 3 1988 F-350 DRW

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    Bike,

    The fuel filter pressure switch (on the filter housing) is a normally open switch that closes to ground (lighting the fuel filter indicator lamp) as a result of a clogged fuel filter. The fuel filter indicator lamp is supplied with +12V (hot in RUN or START) via 15A fuse 18. (From 1988 model year wiring diagram).

    Regards,
     
  3. bike-maker

    bike-maker Full Access Member

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    Just what I was looking for, thanks
     

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