Hi,
I am troubleshooting why my '84 trans am hood scoop flapper is not opening at WOT. I have the Factory service manuals and confirmed that when I cap the vacuum switch (below) the flapper does not open. Also I have tested the solenoid/flapper motor and it does open when apply battery power so I know the motor and flapper are moving.

I checked all wiring and the only item that looks odd is the vacuum ported switch (pictures attached). I don't know alot about these but guessing when vacuum is applied from the manifold at W)T it opens (or closes) and that is what completes the circuit to open the flapper motor (if this logic is wrong please let me know). It appears it is frozen and wont move and assuming that is my problem (the little pintle at the top). I did hook my ohm meter to the 2 leads and applied vacuum and the circuit did not open. So I am guessing this is my issue.I do have strong vacuum from the hose that goes into this switch.

Also guessing this vacuum switch is impossible to find anymore. so wondering if I could make another ported switch work OR even wire a toggle switch to the 2 leads and manually open and close the flapper. Would ideally like to put it back the way it was but not sure parts are available. I did check rockauto and gmpartsdirect neither have it.

Any advice or if I am off track on above logic would be appreciated. thanks

 

https://www.thirdgen.org/forums/hist...ml#post6011690

Vacuum switch (GM #10032130)
The original ACDelco vacuum switch is normally closed (NC).
Therefore, engine OFF - no vacuum - the switch is CLOSED.
Engine RUNNING (idle) - vacuum is high - the switch OPENS.
Engine at WOT - vacuum goes low - the switch CLOSES.
If all of the other switches' conditions are met at that time, then the flap opens.
Or test using this method:
Fail testing the setup
Just revving the engine is not going to activate the solenoid. The engine must be under load i.e. accelerating. But there is a very easy method, which is also described in the 1984 Firebird manual: when the engine is running (oil pressure switch closed) AND the engine is warm (cold override switch closed) then plug off the vacuum line from the vacuum switch. The vac switch closes and current flows to the solenoid, which then should move. If it does, the system is working.

 

Thanks ! This is what I needed. So that confirms the vacuum switch is bad in my case. Now the hunt begins to attempt to find another, although difficult.