In Reply to: Re: From whence does the vacuum line cometh on 87T?, Ari [Profile/Gallery] , Wed, 2 Jan 2002 13:09:57

My wife thanks you every cold morning she sits on her heated seat in the 90S.

No questions about the APC solenoid & connections.

Perhaps the red & blue switches on LH fenderwell are part of the cruise control system! I have yet to even try the cruise in the 87T. I did notice both my cars have this blackish gadget in the LH front wheelwell, and it does connect to the red diaphragm switch, but not the blue one (connected to manifold). So your thought about these could be correct. I read on the Townsend site that the red & blue switches on "older turbo" cars related to the APC controls. And yes I have a smaller vacuum/boost line going thru firewall right by the mastercylinder and it in fact does connect to something in there (boost gage & overboost switch perhaps). It is damn difficult to see anything up in there!

I have never seen a cruise control which used +/- pressure to the diaphragm, only vacuum & bleed offs to modulate speed. I guess I will look into the Bentley tonite under the cruise section and see what she says. In any case I would suspect the diaphragm should be deadheaded and should hold a vacuum from the MityVac; mine is wide open so maybe ruptured?

Since your are an electrical guy, I did note that the underdash pressure switch puts out analog voltage (per Bentley), and that this switch is feedback to the APC. This to me does not sound like an overboost switch which logically should be just an contactor (sort of digital) rather than analog out. Bentley even gives a range of voltage between vacuum and positive pressure and then tells you how to test it. So while not a MAP, it is definitely in the control loop of the APC.

Thanks and any further thoughts welcomed.

DET


posted by 32.97.2...

• From whence does the vacuum line cometh on 87T?, DET, Wed, 2 Jan 2002 12:25:06
  • Re: From whence does the vacuum line cometh on 87T?, Ari , Wed, 2 Jan 2002 13:09:57
    • IIRC-switches: 1-CC on/off 2-boost adj when on n/m, Vas, Wed, 2 Jan 2002 16:27:26
    • Thanks Ari, you might be right again, DET, Wed, 2 Jan 2002 14:50:03 <-- Viewing This Message
      • Pressure transducer, Ari , Wed, 2 Jan 2002 17:16:22
        • I stand corrected, Ari , Wed, 2 Jan 2002 22:39:01
  • Is there a vac diagram under hood on fender? n/m, Micah in NC, Wed, 2 Jan 2002 12:44:58
    • Yes, a small diameter red & blue one., DET, Wed, 2 Jan 2002 14:52:34

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