BMW Coupes and Sedans 1970-1988 Repair Guide

Throttle Valve Switch

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See Figure 1

The throttle valve switch cuts off the fuel supply to avoid engine overrunning. This is done by switch contacts, which are closed when the throttle valve is in the idling position.



Click image to see an enlarged view

Fig. Fig. 1: Throttle valve switch and pin placement

When the throttle valve is moved 2°, the throttle valve switch movement opens the cut-off contacts and closes the acceleration enrichment control. Electrical impulses sent to the control unit determine the fuel quantity required for acceleration. A second switch closes the acceleration enrichment circuit only when the fuel cut-off switch is open.

REMOVAL & INSTALLATION



Except 528e Models
  1. Remove the terminal plug from the throttle valve switch.
  2.  
  3. Remove the switch retaining screws and remove the switch from the throttle shaft.
  4.  
  5. To install the switch, engage the throttle shaft into the switch orifice. Install the retaining screws and terminal plug.
  6.  

528e Models
  1. Unscrew the hose clamp and push back the air hose.
  2.  
  3. Disconnect the accelerator cables.
  4.  
  5. On models with automatic transmissions, disconnect the accelerator cable for the automatic transmission.
  6.  
  7. Disconnect the electrical connector, unscrew the mounting screws and remove the throttle housing.
  8.  
  9. Installation is in the reverse order of removal. Always replace the gasket and adjust the accelerator cable setting.
  10.  

ADJUSTMENT



Except 3.0Si Models

See Figures 1 and 2

  1. Connect an ohmmeter lead to terminals 18 and 2 of the throttle valve switch, after removing the terminal plug.
  2.  
  3. At idle position of the throttle, the meter needle should read 0 resistance.
  4.  
  5. Connect the meter leads to terminals 2 and 3.
  6.  



Click image to see an enlarged view

Fig. Fig. 2: Use an ohmmeter to check the throttle switch adjustment

  1. With the throttle wide open, the meter needle should read 0 resistance.
  2.  
  3. The switch can be moved for small adjustments. If adjustments are unattainable, replace the switch.
  4.  

3.0Si Models
  1. Disconnect the electrical terminal plug from the throttle valve switch and loosen the switch retaining screws.
  2.  
  3. Connect the leads of a calibrated ohmmeter to terminals 17 and 45 of the throttle valve switch.
  4.  
  5. Rotate the switch until the meter needle shows infinity. Rotate the switch in the opposite direction until the meter needle moves to 0 resistance.
  6.  
  7. Mark the housing opposite the center indicator on the switch scale.
  8.  
  9. Rotate the switch clockwise 2° as indicated on the scale.
  10.  

The scale is graduated in1/2° increments.

  1. As the switch is rotated, the meter needle should move to infinity as the switch contacts open.
  2.  
  3. Rotate the switch counterclockwise to the original scale to housing mark. The meter needle should return to 0 resistance.
  4.  
  5. Lock the switch in place with the retaining screws and attach the wire terminal plug.
  6.  

 
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