Quote:
Originally Posted by Shorebilly
What does Item #123, Vacuum Transducer, actually do??.....looks like another balanced diagphragm, with an adjusting screw.....from it's connections, it appears that a vacuum signal is applied to the bottom, from Item #125, Switchover Valve, which is actuated by an electrical signal originating at Item #20, Temperatore coolant Switch 50C....when activated sends a vaccuum Signal to the Automatic Transmission.....Also acted upon by Item #126, Switchover Valve Boost Pressure Aneroid.......I am guessing that this device serves to operate transmission shipt points in relation to Turbo Boost......Note: Input from #125 also connects to ALDA
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Note that I posted the CA diagram. I don't know whether you have a CA vehicle, however, you definitely have the vacuum transducer (blue flying saucer on driver's fenderwell) and this diagram is the only diagram that shows that unit. It's not in the federal diagram. So, either the federal diagram is partially incorrect (possible) or you have a CA vehicle (less likely). The diagram that I posted may, or may not be accurate in all other respects.
Can't help you with the vacuum converter. It's unique to the '85. But, the vacuum transducer is found on many vehicles after '85 including my SDL's. It takes three inputs........one from the vacuum control valve..........one straight vacuum signal.........and one pressurized boost signal from the manifold. The fourth line is the transmission output line. The unit generally holds the vacuum to the trans fairly steady at between 10" and 13" for most driving conditions down to about 1/2 pedal. Then, it gradually reduces vacuum to the trans to about 5" when the pedal is further depressed. When the boost comes on, the unit gradually drops the vacuum down to about 1" at maximum power.
The 50 deg. switch causes the solenoid to close and it raises the vacuum slightly when the engine is cold to smooth the shifts.