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Code 23, Throttle Position Sensor MISADJUSTED - Diesel Electronic Control System: Notes

The throttle Position Sensor (TPS) is a variable resistor that informs the ECM the degree of throttle opening. The sensor is connected to a 5-volt reference signal and has a high resistance value at closed throttle. At wide open throttle, TPS resistance is at its lowest and output to the ECM will be close to 5 volts. Code 23 means that the ECM has seen the following: voltage not between .25-1.35 volts at ECM terminal "A2" for at least 30 seconds, with engine speed between 550-650 RPM.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This test confirms Code 23 and that fault is present.
  2. This test will determine if sensor signal line is shorted to ground.
  3. Adjust Throttle Position Sensor.
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