VW Passat & Audi A4 1990-2000

Throttle Position (TP) Sensor

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OPERATION
Passat 1.9L Turbo Diesel

The throttle position sensor supplies the ECM with a voltage signal regarding the position of the throttle valve. The fuel injection ECM supplies the throttle position sensor with a 5-volt supply signal. This signal passes through the carbon track, over the 2 contacts and returns via the second carbon track to the ECM, which uses the remaining voltage as the throttle position signal. Depending on where the contacts are located on the carbon track (terminals move with the throttle valve), the current must pass through a larger or smaller section of the track. This increases or decreases the circuit resistance, affecting the voltage returning to the ECM. The resistance is at its maximum when the throttle is in the idle position.

TESTING
Passat 1.9L Turbo Diesel

NOTE
The Throttle Position sensor is located on the accelerator pedal and transmits the driver's throttle pedal input to the ECM.

  1. Connect VAG 1551/1552 scan tool
  2.  
  3. Switch ignition ON (but Do NOT start engine).
  4.  
  5. Press "0" and "1" buttons to select "Address Word 01: Engine Electronics".
  6.  
  7. Press "0" and "8" buttons to select "Function 08: Read Measuring Value Block."
  8.  
  9. Press "Q" button to enter input
  10.  
  11. Press "0", "0" and "2" buttons to select "Display Group 2."
  12.  
  13. Press "Q" button to enter input.
  14.  



Click image to see an enlarged view

Fig. Display Group 2 will appear as shown

  1. Observe the throttle position in "Display Zone 2." (The accelerator pedal must not be depressed). The display should show a specification of 0.0 %.
  2.  
  3. Also, check the idle speed switch display in "Display Zone 3." The center position must show "1". The display should read "010."
  4.  
  5. Slowly push on the accelerator pedal until it is fully depressed. Observe "Display Zones 2 and 3".
  6.  



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Fig. Display Zone 2 should show as indicated

  1. Display zone 2 should show the throttle position display as increasing continuously. The specification at WOT position should be 100 %.
  2.  
  3. Display zone 3 should show the center position as changing to "0". The display should read "000".
  4.  

If the end specification value not obtained, press button "0" and "6" to select "Function 06: End Data Transfer."

  1. Press the "Q" button to enter input.
  2.  
  3. Switch "OFF" the ignition.
  4.  
  5. Adjust the throttle position sensor.
  6.  
  7. If the display does not change or is erratic, check the throttle position sensor as follows:
  8.  
    1. Press "0" and "6" buttons to select "Function 06: End Data Transfer".
    2.  
    3. Press "Q" button to enter input.
    4.  
    5. Switch "OFF" the ignition.
    6.  
    7. Disconnect the 6-pin throttle position sensor harness connector.
    8.  




Click image to see an enlarged view

Fig. Showing the 6-pin throttle position harness connector

  1. Measure the TP sensor resistance between terminals 1 and 3 .
  2.  

Specifications should be:



Throttle in Closed Throttle position: 1,000 to 1,500 ohms
 
Throttle in Wide Open Throttle position: 1,500 to 2,500 ohms
 

  1. Check the closed throttle position switch in the TP sensor by measuring resistance between terminals 4 and 6 .
  2.  

The specifications should read:



Throttle in closed throttle position: 1.5k/ohms maximum
 
Throttle depressed: infinite ohms
 

  1. If specifications not obtained, replace the TP sensor.
  2.  

If the proper specifications are obtained, connect a VAG 1598/22 Test Box to the ECM harness connector.



Click image to see an enlarged view

Fig. Testing the 6-Pin connector

  1. Check the wiring between the test box and ECM connector for any open circuits at the following points:
  2.  
  3. Terminal 1 and socket 24
  4.  
  5. Terminal 2 and socket 11
  6.  
  7. Terminal 3 and socket 23
  8.  
  9. Terminal 4 and socket 12
  10.  
  11. Terminal 5 and socket 8
  12.  
  13. Terminal 6 and socket 25
  14.  

In each case, the specification should show a maximum wire resistance of 1.5 ohms.

  1. Check the wires for short to one another, to vehicle ground and to battery positive (B+). The specification should be infinite ohms.
  2.  
  3. If the wiring is OK, replace the ECM.
  4.  

Audi A4 1.8L

NOTE
The Throttle Position (TP) sensor is located inside the throttle valve control module.

When testing, ensure the throttle valve is in the closed throttle position, if necessary adjust accelerator pedal cable. Make sure the cruise control is properly adjusted and the power supply for throttle valve control module is OK.

  1. Connect a VAG 1551 or VAG 1552 scan tool and press buttons "0" and "1" to enter "Engine Electronics: Address Word 01" (with ignition switched "ON", but engine not running).
  2.  
  3. Press buttons "0" and "8" to select "Read Measuring Value Block: Function 08". Then, press the "Q" button to confirm the proper input.
  4.  



Click image to see an enlarged view

Fig. Showing display group field 3 for "End Output: Function 06" (Audi A4 1.8L)

  1. Press buttons "0" and "6" to select "End Output: Function 06", and then press the "Q" button to confirm the input.
  2.  
  3. Switch the ignition off.
  4.  


NOTE
The values displayed in Display Field 3 depend on the calibration of the TP sensor and Do NOT correspond with the actual throttle valve opening in degrees. The maximum displayed value is 90°.

  1. If the throttle angle value does not increase uniformly, replace the throttle valve control module.
  2.  
  3. Carry out the adaptation of throttle valve control module to the ECM.
  4.  



Click image to see an enlarged view

Fig. Indicating Display Field 3 readings (Audi A4 1.8L)

  1. Check the wiring by connecting a VAG 1598/22 test box to the ECM harness connector.
  2.  
  3. Connect a DMM, using the adapter cables from VW 1594 connector test kit.
  4.  
  5. Measure the wiring resistance to check for short circuit between the test box sockets 2 (Ground) and 75 (signal wire). The reading should be infinite ohms.
  6.  
  7. Now, switch the DMM to the voltage measuring range.
  8.  
  9. Switch ignition to "ON".
  10.  
  11. Check the wiring for short circuit to battery positive feed (B+).
  12.  
  13. Note the voltage reading, if applicable. If not, there should be zero volts.
  14.  
  15. Switch ignition to "OFF".
  16.  
  17. Continue the test, depending on whether or not voltage was measured.
  18.  



Click image to see an enlarged view

Fig. Identifying the throttle valve control module 8-pin connector

  1. To continue with wiring testing, disconnect the 8-pin harness connector from the throttle valve control module.
  2.  

If the measured voltage in the previous test was approximately 5 volts, connect the DMM, using adapter cables from VW 1594 connector test kit.

  1. Measure resistance to check for any short circuit between test box sockets 62 (power supply) and 75 (signal wire). The DMM should show infinity.
  2.  
  3. If the measured voltage was approximately battery positive voltage , check the wiring at the 8-pin connector terminal 5 for short circuit to battery B+.
  4.  
  5. If there was no measured voltage, disconnect the 8-pin harness connector from the throttle valve control module.
  6.  
  7. Check the wiring for an open circuit between connector terminal 5 and the ECM test box socket 75 . The DMM should show a maximum resistance of 1.5 ohms.
  8.  
  9. If the wiring is OK, replace the throttle valve control module.
  10.  
  11. Carry out adaptation of the throttle valve control module to the ECM.
  12.  

Audi A4 2.8L
  1. Connect a VAG 1551/1552 scan tool.
  2.  
  3. Switch the ignition to "ON", but Do NOT start the engine.
  4.  
  5. Press the "0" and "1" buttons to select "Address Word 01: Engine Electronics."
  6.  
  7. Press the "0" and "8" buttons to select "Function 08: Read Measuring Value Block"
  8.  
  9. Press the "Q" button to enter input.
  10.  
  11. Press the "0", "0" and "2" buttons to select "Display Group 2."
  12.  
  13. Press the "Q" button to enter input.
  14.  



Click image to see an enlarged view

Fig. Identifying the TP sensor on Audi A4 with 2.8L engine

  1. To check wiring resistance, switch the DMM to measure Ohms Resistance. Connect the DMM between terminals 1 and 2 . The DMM should read 1,500 to 2,600 ohms.
  2.  
  3. Now, measure the resistance between terminals 2 and 3 . It should be, at closed throttle, approximately 750 to 1,300 ohms.
  4.  
  5. Slowly move the throttle from the closed throttle position to wide-open throttle position. Now the specification should show the resistance increasing gradually from closed throttle to WOT, where it should reach a maximum of 3,600 ohms.
  6.  
  7. If any one of the specified values is not obtained, replace the throttle position sensor.
  8.  
  9. To check the voltage supply to the TP sensor, disconnect TP sensor harness connector.
  10.  
  11. Switch the ignition "ON", but Do NOT start the engine.
  12.  



Click image to see an enlarged view

Fig. Showing the TPS connector for Audi A4 2.8L

  1. Switch the DMM to measure "volts" and connect the DMM, in sequence, between terminals 1 (B+) and 2 (GND) and take a reading.
  2.  
  3. Then connect the DMM, in sequence, between terminals 1 (B+) and 3 (signal) and take a voltage reading.
  4.  
  5. In both cases the DMM should show 4.5 to 5.5 volts.
  6.  
  7. If neither check provides the specified value, recheck the TP sensor resistance as described previously. If the specified values are not obtained, check the ECM wiring as follows:
  8.  
    1. Connect the VAG 1598/19 test box to the ECM harness connector.
    2.  
    3. Check the ground (GND) wire for continuity between the TP sensor connector terminal 2 and test box socket D12 .
    4.  
    5. The test box should show a maximum of 1 ohm.
    6.  
    7. Check the B+ wire for continuity between the TP sensor connector terminal 1 and test box socket A3 .
    8.  
    9. The specification should show a maximum 1 ohm.
    10.  
    11. Check the signal wire for continuity between the TP sensor connector terminal 3 and test box socket A24 . The specification should be a maximum 1 ohm.
    12.  

  9. If the specified value is not obtained, determine if an open or short circuit exists in wiring, using a wiring diagram. Repair as necessary.
  10.  


NOTE
If it becomes necessary to repair or replace any of the throttle position sensor electrical terminals, ONLY replace with gold-plated terminals.

  1. If the wiring is OK, replace the ECM.
  2.  

Passat 2.8L
  1. Connect a VAG1551 or VAG1552 scan tool and press buttons "0" and "1" to enter "Engine Electronics: Address Word 01". The ignition is switched "ON"; the engine is not running.
  2.  
  3. Press buttons "0" and "8" to select "Read Measuring Value Block: Function 08".
  4.  
  5. Now, press the "Q" button to confirm input.
  6.  
  7. Press buttons "0", "0" and "3" to input display group number 3 (003), and press "Q" button to confirm input.
  8.  
  9. The display should show: 1-4 = display fields.
  10.  



Click image to see an enlarged view

Fig. Display Group 3 (Passat 2.8L)

  1. Compare the Display Field 3 with the specified values for throttle angle while doing the following:
  2.  
    1. Open the throttle valve slowly while monitoring the degree value in Display Field 3.
    2.  
    3. The value must increase uniformly over the entire range.
    4.  



NOTE
The values displayed in Display Field 3 depend on the calibration of the TP sensor and Do NOT correspond with the actual throttle valve opening in degrees.

  1. If the throttle angle value does not increase uniformly, replace the throttle valve control module.
  2.  
  3. Carry out adaptation of throttle valve control module to ECM.
  4.  

If the display constantly shows 0° or is above 90°, disconnect the 8-pin harness connector for throttle valve control module.



Click image to see an enlarged view

Fig. Indicating the 8-pin harness connector (Passat 2.8L)

  1. Bridge connector terminals 5 and 7 , using adapter cables from VW1594 connector test kit and observe display.
  2.  

When the display is above 90°, replace the throttle valve control module and then carry out adaptation of throttle valve control module to ECM.

When the display is 0°, check the voltage supply to throttle valve control module and wiring to the ECM. If the voltage supply and wiring is OK, replace the ECM.

  1. Now check the voltage supply to the ECM. First, disconnect the 8-pin harness connector for throttle valve control module.
  2.  
  3. Connect a DMM between the harness connector terminals 4 and 7 , using adapter cables from VW1594 connector test kit.
  4.  
  5. Turn the ignition switch to "ON" and measure the voltage. It should be a minimum of 4.5 volts.
  6.  
  7. Switch the ignition to "OFF".
  8.  
  9. Connect the DMM to measure voltage between harness connector terminals 3 and 7 .
  10.  
  11. Switch the ignition to "ON" and measure the voltage. There should be a minimum of 9 volts.
  12.  
  13. Switch the ignition to "OFF".
  14.  
  15. Connect the VAG1598/22 test box to the ECM harness connector.
  16.  
  17. Check the wiring for open circuit between the ECM/test box and the 8-pin harness connector. Make checks at the following points:
  18.  
  19. Connector terminal 1 to ECM test box socket 66
  20.  
  21. Connector terminal 2 to ECM test box socket 59
  22.  
  23. Connector terminal 3 to ECM test box socket 69
  24.  
  25. Connector terminal 4 to ECM test box socket 62
  26.  
  27. Connector terminal 5 to ECM test box socket 75
  28.  
  29. Connector terminal 7 to ECM test box socket 67
  30.  
  31. Connector terminal 8 to ECM test box socket 74
  32.  
  33. At each of these checks, the specification should show a maximum of 1.5 ohms.
  34.  
  35. Also, check the wiring of the 8-pin connector for a short circuit between the wires. Between each wire should show infinite ohms.
  36.  
  37. If the wiring is OK, check the ECM voltage supply.
  38.  
  39. Carry out adaptation of throttle valve control module to ECM.
  40.  

ADAPTATION OF THROTTLE VALVE CONTROL MODULE TO ECM

During "adaptation" with the ignition switched "ON", but the engine not running, the ECM "learns" the closed throttle position (CTP), wide open throttle (WOT) and other positions of the throttle valve control module, and a characteristic curve of the relationship between Throttle Position (TP) sensor (G69) and angle sensor for throttle drive.

Test procedure:

  1. Connect a VAG 1551 or VAG 1552 scan tool and press buttons "0" and "1" to enter "Engine Electronics: Address Word 01" (ignition switched on, but the engine is not running).
  2.  
  3. Press buttons "0" and "4" to select "Basic Setting: Function 04", then press the "Q" button to confirm input.
  4.  
  5. Press buttons "0", "6" and "0" to input display group number "60", and press the "Q" button to confirm input.
  6.  


NOTE
After confirming input of display group "60", adaptation is started. The TP sensor is positioned in closed throttle, wide open throttle, and limp-home positions. Following this procedure, other intermediate steps will create a characteristic curve of the relationship between the TP sensor and the angle sensor for the throttle drive. The ECM stores these values in permanent memory. Afterward, the throttle valve assumes the starting position.



Click image to see an enlarged view

Fig. Display Group 60

  1. If displayed values are OK, allow at least 30 seconds, then end adaptation as soon as possible after 30 seconds by pressing buttons "0" and "6" to select "End Output: Function 06". Press "Q" button to confirm input.
  2.  

ADJUSTING
Passat 1.9L Turbo Diesel


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Fig. Adjusting the cable cam (Passat 1.9L Turbo Diesel)

  1. The cable cam must be set such that in the rest position the extended edge of the wrench surface passes the center of the hole-arrow.
  2.  
  3. Attach the TP sensor with the preassembled cable cam to the mounting block.
  4.  
  5. Install the mounting bracket.
  6.  
  7. Reconnect the 6-pin harness connector.
  8.  
  9. Make fine adjustment with the sensor installed:
  10.  
    1. With M/T, turn the accelerator pedal stop to a position where the "HS" is visible.
    2.  
    3. With A/T, depress the accelerator pedal by hand until the accelerator pedal lies against accelerator pedal stop.
    4.  
    5. Set the sensor operating rod using the adjustment screw so the kickdown switch pressure point is just reached when the accelerator pedal is on the accelerator pedal stop.
    6.  
    7. If the accelerator pedal stop is reached without feeling the pressure point, turn the adjustment screw counterclockwise until the pressure point is reached.
    8.  
    9. If the pressure point is reached before reaching the accelerator stop, turn the operating rod adjustment screw clockwise until the accelerator pedal reaches its stop without resistance.
    10.  
    11. If equipped with A/T, turn the accelerator pedal stop 180° so the inscription "AG" is visible.
    12.  

  11. After adjusting the TP sensor, check the sensor using a VAG 1551/1552 scan tool.
  12.  

REMOVAL & INSTALLATION
Passat 1.9L Diesel


Click image to see an enlarged view

Fig. Throttle position sensor (3) location on the Passat 1.9L Diesel


NOTE
When removing and installing the TP sensor, the mounting bracket (9) must be removed.

Passat 2.8L


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Fig. Showing the location of the throttle valve control module (16) on Passat 2.8L

 
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