Suzuki Samurai/Sidekick/Tracker 1986-1998 Repair Guide

Throttle Position Sensor (TPS)

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OPERATION



See Figure 1

The Throttle Position (TP) sensor is used only on fuel injected engines; carbureted engines utilize throttle position micro-switches, which is described later in this section.

The Throttle Position Sensor (TPS) consists of a contact switch (for idle position) and a potentiometer mounted on the throttle body, and is connected to the throttle valve shaft. The TPS's only function is to convey the positioning of the throttle valve to the ECM. Throttle position when the engine is idling is detected by the contact switch, which turns ON only during idle. An opening of the throttle valve beyond idle is detected by the potentiometer. The ECM supplies a 5 volt reference signal to the TPS, and as the sensor brush moves across the print resistance according to the position of the throttle valve position, the return voltage to the ECM varies accordingly. By monitoring the return voltage, the ECM can detect the exact position of the throttle valve at any point in time.



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Fig. Fig. 1: The internal circuitry of the TP sensor, showing the rotating contact arms

TPS information is used by the ECM to calculate fuel delivery for starting, acceleration and deceleration, as well as an input for idle speed control. TPS data is also used by the ECM for torque converter clutch control.

A broken or loose TPS may cause intermittent bursts of fuel from an injector, which may cause an unstable idle because the ECM detects the throttle is moving.

The TPS is mounted on the side of the throttle body.

TESTING



See Figures 2 through 7

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the wiring harness connector from the TPS.
  4.  
  5. Using an ohmmeter, measure the resistance between the terminals of the TPS according to the accompanying test chart.
  6.  



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Fig. Fig. 2: Throttle Position (TP) sensor test chart for TFI engines



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Fig. Fig. 3: TP sensor connector terminal identification for TFI-equipped models



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Fig. Fig. 4: On TFI engines, first check the resistance when the lever-to-stop screw clearance is 0.012 in. (0.3mm) ...



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Fig. Fig. 5: ... then measure the TP sensor resistance when the clearance is 0.020 in. (0.5mm)

  1. If the resistance values observed during the inspection do not match those presented in the test chart, adjust the installed angle of the TPS. Recheck the sensor after adjusting its position.
  2.  
  3. If the resistance values are still not satisfactory, replace the TPS with a new one.
  4.  



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Fig. Fig. 6: Throttle Position (TP) sensor inspection chart for MFI engines



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Fig. Fig. 7: TP sensor connector terminal identification for MFI-equipped models

ADJUSTMENT



1.3L TFI Engine

See Figures 8 and 9

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the wiring harness connector from the TPS.
  4.  
  5. Disconnect and label the throttle opener vacuum hose from the Vacuum Solenoid Valve (VSV), then attach a hand-held vacuum pump to the throttle opener. Apply 19.7 in. Hg (50 cmHg) vacuum to the throttle opener unit, which should move the throttle valve to the idle position.
  6.  
  7. Insert a 0.012 in. (0.3mm) thick feeler gauge between the throttle valve lever and the throttle stop screw.
  8.  



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Fig. Fig. 8: Insert a 0.012 in. (0.3mm) thick feeler gauge between the throttle stop screw and the throttle valve lever to properly adjust the TP sensor



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Fig. Fig. 9: Slowly rotate the TP sensor until the ohmmeter changes from infinite resistance to 0 ohms (continuity), then tighten the TP sensor screws

  1. Loosen the TPS mounting bolts, then attach an ohmmeter to TPS terminals C and D.
  2.  
  3. Rotate the TPS fully clockwise, then turn it slowly counterclockwise until the ohmmeter changes from infinite resistance to 0 ohms (continuity).
  4.  
  5. Tighten the TPS mounting bolts to 31 inch lbs. (3.5 Nm).
  6.  
  7. Insert a 0.016 in. (0.4mm) thick feeler gauge between the throttle valve lever and the throttle stop screw, and recheck the sensor resistance between terminals C and D. Resistance should be infinite.
  8.  
  9. Insert a 0.008 in. (0.2mm) thick feeler gauge between the throttle valve lever and the throttle stop screw, and recheck the sensor resistance between terminals C and D. Resistance should be 0-500 ohms.
  10.  
  11. If the TPS resistance values are not as specified in Steps 8 and 9, the sensor is incorrectly adjusted; perform the adjustment procedure again.
  12.  


WARNING
The throttle stop screw is precisely adjusted at the factory-never remove or adjust it.

  1. Reconnect all wiring harness connectors and vacuum hoses after the test is complete.
  2.  

1.6L TFI Engine

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the wiring harness connector from the TPS.
  4.  
  5. Disconnect and label the throttle opener vacuum hose from the Vacuum Solenoid Valve (VSV), then attach a hand-held vacuum pump to the throttle opener. Apply 19.7 in. Hg (50 cmHg) vacuum to the throttle opener unit, which should move the throttle valve to the idle position.
  6.  
  7. Insert a 0.016 in. (0.4mm) thick feeler gauge between the throttle valve lever and the throttle stop screw.
  8.  
  9. Loosen the TPS mounting bolts, then attach an ohmmeter to TPS terminals C and D.
  10.  
  11. Rotate the TPS fully clockwise, then turn it slowly counterclockwise until the ohmmeter changes from infinite resistance to 0 ohms (continuity).
  12.  
  13. Tighten the TPS mounting bolts to 31 inch lbs. (3.5 Nm).
  14.  
  15. Insert a 0.020 in. (0.5mm) thick feeler gauge between the throttle valve lever and the throttle stop screw, and recheck the sensor resistance between terminals C and D. Resistance should be infinite.
  16.  
  17. Insert a 0.012 in. (0.3mm) thick feeler gauge between the throttle valve lever and the throttle stop screw, and recheck the sensor resistance between terminals C and D. Resistance should be 0-500 ohms.
  18.  
  19. If the TPS resistance values are not as specified in Steps 8 and 9, the sensor is incorrectly adjusted; perform the adjustment procedure again.
  20.  


WARNING
The throttle stop screw is precisely adjusted at the factory-never remove or adjust it.

  1. Reconnect all wiring harness connectors and vacuum hoses after the test is complete.
  2.  

1.6L MFI Engine

See Figure 10

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the wiring harness connector from the TPS.
  4.  
  5. Insert a 0.026 in. (0.13mm) thick feeler gauge between the throttle valve lever and the throttle stop screw.
  6.  
  7. Loosen the TPS mounting bolts, then attach an ohmmeter to TPS terminals A and B.
  8.  
  9. Rotate the TPS fully counterclockwise, then turn it slowly clockwise until the ohmmeter changes from continuity to no continuity (infinite resistance).
  10.  



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Fig. Fig. 10: When adjusting the TP sensor, ensure that there is no continuity between terminals A and B when a 0.037 in. (0.8mm) feeler gauge is inserted between the throttle stop screw and lever

  1. Tighten the TPS mounting bolts to 31 inch lbs. (3.5 Nm).
  2.  
  3. Insert a 0.037 in. (0.8mm) thick feeler gauge between the throttle valve lever and the throttle stop screw, and recheck the sensor resistance between terminals A and B. Resistance should be infinite.
  4.  
  5. Insert a 0.020 in. (0.5mm) thick feeler gauge between the throttle valve lever and the throttle stop screw, and recheck the sensor resistance between terminals A and B. The sensor should exhibit continuity.
  6.  
  7. If the TPS resistance values are not as specified in Steps 7 and 8, the sensor is incorrectly adjusted; perform the adjustment procedure again.
  8.  


WARNING
The throttle stop screw is precisely adjusted at the factory-never remove or adjust it.

  1. Reconnect all wiring harness connectors and vacuum hoses after the test is complete.
  2.  

1.8L Engine

See Figure 11

  1. Start the engine and allow it to reach normal operating temperature.
  2.  
  3. Ensure that the fast idle cam and cam follower lever are not in contact with each other.
  4.  
  5. Loosen the TPS mounting bolts.
  6.  
  7. Remove the ECM with the wiring harness attached to it. Position it on the floor of the vehicle.
  8.  



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Fig. Fig. 11: During adjustment, use a DVOM connected to ECM terminal E33-17 and ground to measure the TP sensor voltage at idle and Wide Open Throttle (WOT) positions

  1. Connect the positive lead of a Digital Volt-Ohmmeter (DVOM), switched to the voltmeter function, to ECM terminal E33-17, and the negative lead to a good chassis ground.
  2.  
  3. While you observe the DVOM, have an assistant slowly rotate the TPS clockwise and counterclockwise until a voltage of 0.35-0.13 volt (0.5 volt is preferred) is achieved.
  4.  
  5. Tighten the TPS mounting bolts to 22 inch lbs. (2.5 Nm).
  6.  
  7. Have your assistant open the throttle valve to the Wide Open Throttle (WOT) position. Observe the DVOM; the voltage should be 3.5-4.5 volts (4.0 volt is preferred).
  8.  
  9. Reinstall the ECM.
  10.  

REMOVAL & INSTALLATION



TFI Engines

See Figures 12 through 17

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the wiring harness connector from the TPS.
  4.  
  5. Remove the TP sensor wire terminals from the harness plastic connector by using a thin, pointed tool to disengage the terminals' retaining latches. Pull the terminals out of the connector body.
  6.  
  7. Remove the mounting bolts, then pull the TPS off of the throttle body.
  8.  



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Fig. Fig. 12: Use an awl or similar tool to disengage the wiring terminals from the connector



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Fig. Fig. 13: The thin metal tool is used to depress the plastic retaining tab so that the terminal can be withdrawn from connector body



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Fig. Fig. 14: Loosen the two TP sensor mounting bolts ...



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Fig. Fig. 15: ... then remove the sensor from the throttle body

To install:
  1. If necessary, clean the TPS-to-throttle body mating surface of all dirt, grime or oil.
  2.  
  3. Position the TPS on the throttle body so that the mounting bolt slots are slightly askew from the bolt holes in the throttle body (as shown in the illustration). After the TPS is flush against the throttle body, rotate the sensor clockwise until the sensor slots are aligned with the throttle body holes. Install and hand tighten the sensor mounting bolts.
  4.  



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Fig. Fig. 16: When installing the TP sensor, slide onto the throttle body so that the mounting slots are slightly askew from the bolts holes, then rotate the sensor until the holes align



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Fig. Fig. 17: Re-engage the wiring terminals in the plastic connector housing-give each wire a slight tug to ensure that they will not back out of the connector

  1. Insert the four TPS wire terminals into the plastic connector until they are properly engaged. Give each wire a slight tug to ensure that they will not come out of the connector.
  2.  
  3. Adjust the TPS angle, as described under TPS testing.
  4.  
  5. Tighten the sensor mounting bolts to 31 inch lbs. (3.5 Nm).
  6.  
  7. Reconnect the wiring harness connector to the TPS.
  8.  
  9. Conenct the negative battery cable.
  10.  

MFI Engines

See Figures 18 and 19

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the wiring harness connector from the TPS.
  4.  
  5. Remove the mounting bolts, then pull the TPS off of the throttle body.
  6.  



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Fig. Fig. 18: When installing the TP sensor on the throttle body, ensure that the tangs (B) engage in the slots (A) of the sensor mechanism-1.6L MFI engines



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Fig. Fig. 19: On 1.8L engines, the slots (A) of the sensor mechanism should retain the two small pins (B) of the throttle valve shaft

To install:
  1. If necessary, clean the TPS-to-throttle body mating surface of all dirt, grime or oil.
  2.  
  3. Position the TPS on the throttle body so that the sensor pick-up lever can properly engage with the throttle body lever tangs (B).
  4.  
  5. Install and hand-tighten the sensor mounting bolts.
  6.  
  7. Insert the four TPS wire terminals into the plastic connector until they are properly engaged. Give each wire a slight tug to ensure that they will not come out of the connector.
  8.  
  9. Adjust the TPS angle, as described under TPS testing.
  10.  
  11. Reconnect the wiring harness connector to the TPS.
  12.  
  13. Conenct the negative battery cable.
  14.  

 
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