Chrysler Front Wheel Drive Cars 4-CYL 1981-1995 Repair Information

Throttle Position Sensor (TPS)

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OPERATION



Chrysler Mikuni Feedback Carburetor System

The Mikuni feedback carburetor system is used only on 2.6L engines.

The Throttle Position Sensor (TPS) is a rotation type variable resistor that rotates together with the carburetor throttle shaft to sense the throttle valve angle. As the throttle shaft rotates, the TPS output voltage changes and the PCM detects the throttle valve opening based on the change of the voltage.

Using the TPS output signal, engine speed signal and other signals, the PCM judges the engine operating mode and controls the air-fuel ratio, etc. for an optimum air-fuel mixture in that mode.

Chrysler Electronic Fuel Injection (EFI) and Multi-Point Fuel Injection (MFI) Systems

See Figures 1 and 2

Click image to see an enlarged view

Fig. Fig. 1: On 2.2L Turbo III and 2.5L Turbo I models, the TPS and AIS are mounted on throttle body next to each other



Click image to see an enlarged view

Fig. Fig. 2: Remove the two retaining screws, then slide the TPS off of the throttle shaft

The MFI system is used on 2.2L and 2.5L turbocharged and flex fuel engines.

The Throttle Position Sensor (TPS) is a variable resistor which is activated by the movement of the throttle shaft. It is mounted on the throttle body and senses the angle of the throttle blade opening. The voltage that the sensor produces increases or decreases according to the throttle blade opening. This voltage is transmitted to the engine controller where it is used along with data from other sensors to adjust the air/fuel ratio to varying conditions and during acceleration, deceleration, idle, and wide open throttle operations.

Eagle Throttle Body Fuel Injection (TBI) System

The Eagle TBI system is used only on 2.5L Premier engines.

The Throttle Position Sensor (TPS) is mounted on the throttle body and connected to the throttle valve shaft. The sensor is a variable resistor that provides the PCM with an input voltage which indicates throttle valve position. The input voltage to the PCM from the TPS varies in an approximate range of from 1 volt at minimum throttle opening (idle) to 5 volts at wide open throttle. The PCM uses TPS input voltages to determine current engine operating conditions.

There a 2 different types of sensors, one used with manual transmission and one used with automatic transmission. The TPS used with the automatic transmission has 2 integral wiring harness connectors (one is a 4 pin connector and one is a 3 pin connector) that plug into the engine wire harness. The 4 pin connector supplies input to the PCM while the 3 pin connector supplies input to the transmission control unit. The TPS used with the manual transmission uses a single wiring harness connector.

TESTING



Chrysler Mikuni Feedback Carburetor System
  1. Disengage the TPS connector.
  2.  
  3. Check resistance with a circuit tester (ohm range) between the orange wire and the light green/red wire.
  4.  
  5. Check to ensure that when throttle valve is slowly operated from closed to wide open position, resistance changes smoothly. Resistance should be:

    Closed throttle-Approximately 3500-6500 ohms
     
    Wide Open Throttle (WOT)-Approximately 100-1000 ohms
     

  6.  
  7. If the TPS resistance is not within the specifications, replace the TPS sensor with a new one.
  8.  

Chrysler Electronic Fuel Injection (EFI) and Multi-Point Fuel Injection (MFI) Systems

  1. Before testing the TPS, check the terminals at the TPS and PCM to ensure good connections (tight and clean).
  2.  
  3. If available, connect Chrysler Diagnostic Readout Box (DRB II) or an equivalent scan tool to the diagnostic connector.
  4.  
  5. If using a scan tool, place it into Sensor Test Mode number 5.
  6.  
  7. Turn the ignition switch to the ON position.
  8.  
  9. If a DRB scan tool is not available, perform the following. While the throttle is completely closed, check the output voltage at the orange/dark blue tracer wire of the connector by backprobing the connector with a multimeter set to measure voltage. Make certain not to pierce the wire insulation to take a reading, use only the backprobe method. (for more information on testing methods of circuits, refer to Chassis Electrical .)
    1. If the voltage is 1 / 2 -1 1 / 2 volts for the MFI system, or lower than 1 volt for the EFI system with the throttle completely closed, proceed to the next step.
    2.  
    3. If the voltage is above 1 1 / 2 volts (MFI system) or 1 volt (EFI system) with the throttle completely closed, the TPS is defective and must be replaced with a new one.
    4.  

  10.  
  11. While slowly opening the throttle to wide open, watch the voltage reading.
    1. If the voltage change was a smooth transition, proceed to the next step.
    2.  
    3. If the voltage was irregular or no voltage change was detected, the TPS is defective and must be replaced with a new one.
    4.  

  12.  
  13. With the throttle completely open (wide open throttle), read the voltage again.
    1. If the maximum voltage detected was at least 3.5 volts with the throttle completely open, proceed to the next step.
    2.  
    3. If the maximum voltage was not 3.5 volts or more, the TPS is defective and must be replaced with a new one.
    4.  

  14.  
  15. The TPS is functioning correctly if it passed all steps in this test.
  16.  

Eagle Throttle Body Fuel Injection (TBI) System
  1. Turn the ignition switch to the ON .
  2.  
  3. Disconnect the throttle position sensor electrical connector.
  4.  


CAUTION
To prevent damage to the connectors and/or wiring, all testing should be performed by back probing the rear of the electrical connector.

  1. Measure the voltage between terminals B and C of the TPS harness connector. The measured voltage should be approximately 5.0 volts.

    If the measured voltage is within specifications, proceed to the next step
     
    If the measured voltage is not within specifications, inspect the power supply circuitry and wiring using a Chrysler DRB II tester.
     

  2.  
  3. Turn the ignition switch to the OFF position.
  4.  
  5. Check for continuity between terminal B and ground.

    If continuity existed, proceed to the next step
     
    If continuity did not exist, inspect the wire for an open using a Chrysler DRB II tester.
     

  6.  
  7. Reconnect the TPS connector and turn the ignition switch to the ON position.
  8.  
  9. Measure the voltage between terminal A and ground. Voltage should be approximately 0.5-1.0 volts. If the measured voltage is not within specifications, adjust the sensor and retest. If sensor can not be adjusted within specifications, replace the sensor.
  10.  

ADJUSTMENT



Only the Premier model is equipped with a Throttle Position Sensor (TPS) which requires adjustment after installation.

A high impedance digital voltmeter (such as C-4845 or equivalent) will be needed for this adjustment. The adjustment can also be performed on a Diagnostic Tester DRB-II and is the preferred method. Refer to the DRB-II manufacturer's instructions for further information.

  1. Disengage the Idle Speed Control (ISC) motor electrical connector.
  2.  
  3. When checking/setting the TPS, connect Tool 7088 to the ISC motor. Retract the ISC plunger until the throttle lever contacts the idle stop screw and the plunger does not contact the throttle lever.
  4.  

Modify the electrical connector of the ISC motor Exerciser Tool 7088 as follows so that it will connect to the ISC motor: use a hobby knife to cut a groove in terminal (A) that is the same size and shape as the grooves in Terminals (B) and (D).

  1. When checking/setting the TPS, check the input and output voltages at the inner 4 terminal connector (inner is defined to be the TPS wire connector nearest to the throttle body).
  2.  
  3. Turn the ignition key to the ON position.
  4.  
  5. Do not unfasten the TPS wire harness connector. Insert the voltmeter test leads through the back of the wire harness connector (back probe them). The TPS terminals are marked A , B , C and D .
  6.  
  7. Check the TPS input voltage at the harness connector. Locate terminal D and insert the negative (-) lead of the voltmeter into the back of it. Insert the positive (+) lead of the voltmeter into the back of terminal A .
  8.  
  9. Note the sensor input voltage on the voltmeter (between terminals D and A ).
  10.  
  11. Check the TPS output voltage. Disconnect the voltmeter positive (+) from terminal A and connect it to terminal B .
  12.  
  13. Note the sensor output voltage on the voltmeter (terminal B and D ).
  14.  
  15. Divide the output voltage by the input voltage (terminals' B & D voltage divided by terminals' D & A voltage). The resulting output ratio should be 0.925 to 0.935 (92.5 to 93.5).
  16.  
  17. If necessary, adjust the TPS sensor until the correct ratio is obtained. To adjust the voltage readings, loosen the sensor top retaining screw and pivot the sensor for a fine adjustment. Loosen the sensor bottom retaining screw and pivot the sensor for a coarse adjustment.
  18.  

For example: if the input voltage is 5 volts and the output voltage is 0.4 volts; divide 0.4 by 5 (0.4/5 = 0.08 or 8).

  1. Tighten the retaining screws until snug once the TPS has been adjusted correctly.
  2.  

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Remove the electrical connector from the throttle position sensor.
  4.  
  5. Remove the throttle position sensor mounting screws.
  6.  
  7. If necessary, remove the wire harness mounting bracket screws.
  8.  
  9. Lift the throttle position sensor off of the throttle shaft.
  10.  

To install:

When installing the TPS on the 2.5L Premier engine, ensure that the TPS lever is on top of the throttle lever.

  1. Install the throttle position sensor on the throttle shaft and install the mounting screws. Tighten the screws to 17 inch lbs. (2 Nm).
  2.  

When installing the throttle position sensor, ensure that the TPS lever is on top of the throttle lever.

  1. Plug electrical connector back into the throttle position sensor.
  2.  
  3. Connect the negative battery cable.
  4.  
  5. On Premier models, adjust the TPS unit as described earlier in this section.
  6.  
  7. Tighten the retaining screws until snug once the TPS has been adjusted correctly.
  8.  

 
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