Forenza 2007

Throttle Position Sensor

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Operation



Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008

The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft of the throttle body. The TP sensor electrical circuit consists of a 5 Volts supply line and a ground line, both provided by the Engine Control Module (ECM). The ECM calculates the throttle position by monitoring the voltage on this signal line. The TP sensor output changes as the accelerator pedal is moved, changing the throttle valve angle. At a closed throttle position, the output of the TP sensor is low, about 0.5 Volts. As the throttle valve opens, the output increases so that, at Wide Open Throttle (WOT), the output voltage will be about 5 Volts. The ECM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts of fuel from the injector and an unstable idle, because the ECM thinks the throttle is moving. A problem in any of the TP sensor circuits should set a Diagnostic Trouble Code (DTC) P0121 or P0122. Once the DTC is set, the ECM will substitute a default value for the TP sensor and some vehicle performance will return. A DTC P0121 will cause a high idle speed.

Testing



Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008

The Throttle Position (TP) sensor incorporates 2 TP sensors into one housing. TP sensor 1 and TP sensor 2 each have a 5 volt reference circuit supplied by the ECM. The ECM supplies each TP sensor with a low reference circuit. Each TP sensor supplies the ECM with a signal voltage that is proportional to the throttle plate position. The TP signal voltages are opposite from one another. TP sensor 1 is pulled up to reference voltage as the throttle plate is opened. The TP sensor 2 is pulled down to low reference as the throttle plate is opened.


NOTE
The Throttle Position (TP) sensors are part of the Throttle Actuator Control (TAC) system.

  1. Scan tool readings for the TP Sensor should read between 0.36- 0.96 Volts at idle to above 4 Volts at WOT.
  2.  
  3. If sensor is out of range check wiring for an open or short.
  4.  
  5. Check for 5Volts reference from the ECM.
  6.  
  7. Replace sensor if readings are not within specifications.

    Click image to see an enlarged view

    Fig. Throttle Position (TP) sensors schematic

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