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Electromagnetic Switching Valve

NOTE: 633CSi and 733i models are equipped with two or three electromagnetic switching valves. The switching valve for the transmission controlled spark system can be identified by the Black cap.
  1. With ignition switch in the "ON" position and engine stopped, shift transmission into 4th gear. Disconnect switching valve-to-distributor advance unit vacuum hose.
  2. Disconnect remaining switch valve vacuum hose at thermo valve (320i) or at throttle housing (633CSi and 733i) and blow air into hose.
  3. Switching valve is okay if air passes through it with transmission in 4th gear but is blocked when transmission is shifted out of 4th gear. If not, switching valve is defective and should be replaced.
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