Re: Unreliable brake vacuum relay

["Chuck Hursch" <chursch@yahoo.com>]

Mitchell Oates wrote Friday, March 29, 2002 12:02 AM:

>       Nathaniel, are you talking about the relay on the vacuum
> switch itself, or a separate relay activated by the vacuum
switch?
>       Here's my setup - I have one of the small vacuum switches
> from Wilde Evolutions. The relay on the vacuum switch activates
> the coil on a big honking Prestolite starter solenoid made for
a
> Class 8 truck (got it for 3 bucks, there are some advantages to
> working for Freightliner).  The Prestolite relay is what
actually
> switches power on and off to the 18 amp Gast vacuum pump.
> Haven't had a problem in 8000 miles.
>        Instead of having the vacuum switch directly turning the
> vacuum pump on and off, just get a decent starter solenoid.
Wire it
> so that the vacuum switch is controlling the coil of the
solenoid,
> and use the solenoid to actually interrupt power to the pump.
>
>                                               Mitch Oates

If his vacuum setup is like mine, the vacuum sensor is
controlling a relay (probably Potter Brumfeld 40A), which itself
controls the pump.  The starter relay should fix the frying of
the relays, but there's still the issues of too much cycling and
noise (if he finds those to be issues, which I certainly do).


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