vacuum switch attached to brake?

[jman340]

Just got my 86 GMC 1500 back on the road, but still have the dash pad and other dash pieces off. I noticed a vacuum sound when I stepped on the brake, and looked under and noticed a vacuum switch attached to the brake petal. What is this, and should I be hearing it?
Thanks
John

[zieg85]

It disengages the cruise control

[Boone83K10]

yes it is cruise. I tried to take my cruise off and I lost converter lockup.

[jman340]

I'm guessing it shouldn't sound like a vacuum leak. I no longer have cruise, so can I just cap the line to it, or will that disable the converter lock also?

[frotosride]

I'm guessing it shouldn't sound like a vacuum leak. I no longer have cruise, so can I just cap the line to it, or will that disable the converter lock also?

It will disable lockup because the vacuum switch is part of the lockup wiring.

[zieg85]

Your vacuum power booster may be what you are hearing.  Disconnect the vacuum to the booster and determine if you still hear the hiss.