Suzuki Samurai/Sidekick/Tracker 1986-1998 Repair Guide

Throttle Position Micro-Switches

Print

OPERATION



The throttle position is indicated to the ECM by two position micro-switches: the idle position micro-switch and the wide open position micro-switch.

The idle position micro-switch closes its circuit when the throttle valve in the idle position. The wide open throttle micro-position switch closes its circuit when the throttle valve is in the Wide Open Throttle (WOT) position. By monitoring these two circuits, the ECM can detect extreme throttle valve positions, and alter the air/fuel mixture accordingly.

TESTING



Idle Position Micro-Switch

See Figures 1, 2, 3 and 4

  1. Start the engine and allow it to warm up to normal operating temperature.
  2.  
  3. Turn the engine OFF .
  4.  
  5. Locate the check terminal behind the glove box, under the left-hand side of the instrument panel.
  6.  
  7. Attach the negative lead of a Digital Volt-Ohmmeter (DVOM), switched to the ohmmeter setting, to the check terminal, and the positive DVOM lead to a good chassis ground.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: The micro-switch test terminal is located behind the glove compartment door, under the instrument panel

  1. Turn the ignition ON .
  2.  
  3. While observing the DVOM, have an assistant slowly move the throttle lever from idle to Wide Open Throttle (WOT) and back again. The DVOM should show circuit continuity at idle and WOT, but no continuity at half-throttle. If the test terminal circuit does not function as described, proceed with the test. Otherwise the idle throttle position micro-switch is functioning properly.
  4.  
  5. Remove the carburetor from the engine, as described in Fuel System .
  6.  
  7. Rotate the fast idle cam counterclockwise, then insert a metal pin into the cam and bracket holes to secure them in position.
  8.  



Click image to see an enlarged view

Fig. Fig. 2: Observing the switch resistance with a DVOM, check the idle position micro-switch



Click image to see an enlarged view

Fig. Fig. 3: The resistance shown on the DVOM should switch from 0 ohms to infinite resistance when the throttle valve-to-bore clearance is 0.014-0.024 in. (0.36-0.62mm)

  1. Attach the DVOM, set on the ohmmeter function, to the idle position micro-switch terminals. Check for switch continuity (0 ohms) when the throttle valve is in the idle position. If the switch resistance observed was not as described, replace the switch with a new one.
  2.  
  3. Open the throttle valve 1 / 4 to 1 / 2 , then observe the switch resistance again. The switch should register infinite resistance (no continuity). If the switch resistance observed was not as described, replace the switch with a new one.
  4.  
  5. Observe the DVOM, and slowly open the throttle valve until the throttle valve-to-carburetor bore clearance is 0.014-0.024 in. (0.36-0.62mm). The DVOM should switch from 0 ohms (continuity) to infinite resistance (no continuity) at this point.
  6.  



Click image to see an enlarged view

Fig. Fig. 4: Adjust the throttle valve-to-bore clearance by bending the lever indicated

  1. If the resistance does not change at the point specified, bend the lever until the resistance transition happens at the precise point indicated. Bend the lever down if the clearance is below specification when the transition occurs, and bend it up if the specification is too large.
  2.  
  3. Install the carburetor.
  4.  

Wide Open Throttle (WOT) Position Micro-Switch

See Figures 5, 6 and 7

  1. Start the engine and allow it to warm up to normal operating temperature.
  2.  
  3. Turn the engine OFF .
  4.  
  5. Locate the check terminal behind the glove box, under the left-hand side of the instrument panel.
  6.  
  7. Attach the negative lead of a Digital Volt-Ohmmeter (DVOM), switched to the ohmmeter setting, to the check terminal, and the positive DVOM lead to a good chassis ground.
  8.  
  9. Turn the ignition ON .
  10.  



Click image to see an enlarged view

Fig. Fig. 5: Use an ohmmeter to test the function of the Wide Open Throttle (WOT) micro-switch-attach the ohmmeter to the switch connectors as shown

  1. While observing the DVOM, have an assistant slowly move the throttle lever from idle to Wide Open Throttle (WOT) and back again. The DVOM should show circuit continuity at idle and WOT, but no continuity at half-throttle. If the test terminal circuit does not function as described, proceed with the test. Otherwise the idle throttle position micro-switch is functioning properly.
  2.  
  3. Remove the carburetor from the engine, as described in Fuel System .
  4.  
  5. Attach the DVOM, set on the ohmmeter function, to the WOT position micro-switch terminals. Check for switch continuity (0 ohms) when the throttle valve is in the idle position. If the switch resistance observed was not as described, replace the switch with a new one.
  6.  
  7. Open the throttle valve to the WOT position, then observe the switch resistance again. The switch should register infinite resistance (no continuity). If the switch resistance observed was not as described, replace the switch with a new one.
  8.  



Click image to see an enlarged view

Fig. Fig. 6: While observing the ohmmeter, slowly open the throttle valve until the valve-to-bore clearance is 0.24-0.28 in. (6.0-7.2mm)-the resistance should change from 0 ohms to infinite resistance



Click image to see an enlarged view

Fig. Fig. 7: To adjust the valve-to-bore clearance, bend the lever (1) until the proper clearance is reached

  1. Observe the DVOM, and slowly open the throttle valve until the throttle valve-to-carburetor bore clearance is 0.24-0.28 in. (6.0-7.2mm). The DVOM should switch from 0 ohms (continuity) to infinite resistance (no continuity) at this point.
  2.  
  3. If the resistance does not change at the point specified, bend the lever until the resistance transition happens at the precise point indicated. Bend the lever down if the clearance is below specification when the transition occurs, and bend it up if the specification is too large.
  4.  
  5. Install the carburetor.
  6.  

REMOVAL & INSTALLATION



See Figure 8

  1. Remove the carburetor from the engine.
  2.  
  3. Disengage the micro-switch actuating springs from both switches.
  4.  
  5. Loosen the micro-switch bracket retaining machine screws, then pull the bracket and switches of the carburetor.
  6.  


WARNING
Do not disassemble the micro-switches from the mounting bracket; replace the bracket and switches together as a unit.



Click image to see an enlarged view

Fig. Fig. 8: To remove the micro-switches, detach the two springs, loosen the screws and separate the bracket from the carburetor

To install:
  1. Install the bracket and switches onto the side of the carburetor, then tighten the retaining machine screws until secure.
  2.  
  3. Reattach the actuating springs to the micro-switches.
  4.  
  5. Install the carburetor on the engine.
  6.  

 
label.common.footer.alt.autozoneLogo