BMW Cars 1999-06

Throttle Position Sensor

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Operation



The Throttle Position Sensors (TPS) are used to tell the control unit when the throttle is fully closed or fully open. They are mounted in a single housing on the end of the throttle assembly. If either switch fails, the control unit will use air meter signals to calculate idle and full load control and a fault code will be set in memory.

Removal & Installation



The throttle position switch provides the DME unit information regarding when the throttle is wide open and when it is at idle position. On M20 and S14 engines, the switch must be adjusted when replaced.

  1. Turn the ignition switch OFF .
  2.  
  3. Unplug the connector from the switch body.
  4.  
  5. Remove the 2 screws from the switch body and pull the switch off the throttle body. If necessary, for additional room, remove the throttle body assembly.
  6.  

To install:

  1. Replace the switch and tighten the 2 screws. Attach the electrical connector.
  2.  
  3. On M20 and S14 engines adjust the switch as follows:
    1. Unplug the switch connector.
    2.  
    3. Using a digital ohmmeter or continuity tester check for continuity between terminals 4 and 6 (automatic transmission) or 2 and 18 (manual transmission) when the throttle is closed (idle).
    4.  
    5. Check for continuity between terminals 4 and 5 (automatic transmission) or 3 and 18 (manual transmission) when the throttle is fully open.
    6.  
    7. Loosen the screws on the side of the housing and adjust the switch as necessary.
    8.  

  4.  



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Fig. Disconnecting the throttle position switch-M42 engine



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Fig. Location of the throttle position switch-S38 engine, S14 is similar

Testing



Use a BMW service tester, the OBD I blink code or on OBD II vehicles, use a suitable Data Scan Tool (DST) to check for faults and/or if capable, to read the values of the components. If this diagnostic equipment is not available, proceed as follows.


CAUTION
When checking component values (volts or ohms) a suitable digital volt/ohmmeter must be used otherwise the circuit and/or component may be damaged.

M20 And S14 Engines
  1. Unplug the switch connector and use a continuity tester or ohmmeter for this test.
  2.  
  3. There should be continuity between terminals 4 and 6 (automatic transmission) or 2 and 18 (manual transmission) when the throttle is closed (idle).
  4.  
  5. There should be continuity between terminals 4 and 5 (automatic transmission) or 3 and 18 (manual transmission) when the throttle is fully open.
  6.  
  7. Loosen the screws on the side of the housing to adjust the switch. If the switch cannot be correctly adjusted for both test results, replace the switch.
  8.  



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Fig. Throttle position switch pinout. LL is the idle position and Vl is the full load position-M20, and S14 engines with manual transmissions



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Fig. Throttle position switch pinout. LL is the idle position and Vl is the full load position-M20 engines with automatic transmissions



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Fig. Throttle position switch mounted on the end of the throttle shaft

M42 And M50 Engines
  1. With the ignition switch ON the potentiometer should receive 5 volts at connector terminal 1.
  2.  
  3. With the ignition switch OFF , detach the potentiometer connection. There should be 4.6 kilo-ohms between terminals 1 and 3 of potentiometer.
  4.  
  5. Connect the ohmmeter to terminals 1 and 2 of the potentiometer. Move the throttle throughout the range of movement. The resistance must change smoothly without any jumps, skips or breaks. The resistance should range from 0.8-1.2 ohms to 3.2-4.8 ohms.
  6.  



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Fig. Throttle position potentiometer pinout shown from the wiring harness side of the connector-M42 and M50 engines



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Fig. Disconnecting the throttle position potentiometer-M42 engine

 
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