5.14.1 Description

To enable closed loop control, the position of the throttle plate is supplied to the ECM by two feedback potentiometers in the throttle body. The feedback potentiometers have a common 5V supply and a common ground connection from the ECM, and produce separate linear signal voltages to the ECM proportional to the position of the throttle plate.

The ECM uses the signal from feedback potentiometer 1 as the primary signal of throttle plate position, and the signal from feedback potentiometer 2 for plausibility checks.

• The signal from feedback potentiometer 1 varies between 0.5V (0% throttle open) and 4.5V (100% throttle open).
• The signal from feedback potentiometer 2 varies between 4.5V (0% throttle open) and 0.5V (100% throttle open)

There are two diagnostic checks on the output signal of this sensor: -

1. A range check, where a fault is detected if the signal voltage exceeds a minimum or maximum threshold.
2. A rationality check as detailed by the MAF sensor section.
   Throttle Position Sensor
   
   

   Component/System	Fault Codes	Monitoring Strategy Description	Malfunction Criteria	Threshold value	Secondary Parameter	Enable Conditions	Time Required	MIL Illumination
   Throttle Position Sensor	P0122 P0222	Range check (minimum)	Voltage	< 0.156V	0.100 s / continuous						two driving cycles
   	P0123 P0223	Range check (maximum)		> 4.85V
   	Rationality check		Test combined with MAF sensor

If the above table does not include details of the following enabling conditions: - IAT, ECT, vehicle speed range, and time after engine start-up then the state of these parameters has no influence upon the execution of the monitor.