Code 23, Throttle Position Sensor MISADJUSTED: Notes
WARNING: This page does not describe the selected car, but rather 22 other vehicles, including the 1990 GMC Vandura Special, 1990 GMC Vandura, 1990 GMC Value Van, 1990 GMC Suburban, and 1990 GMC Rally Camper Special. However, it is still accessible from the selected car via links, so may be relevant.
The Throttle Position Sensor (TPS), a variable resistor, informs the ECM of throttle opening. The TPS, connected to a 5-volt reference signal, 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 the ECM has seen the following: voltage is not .25-1.35 volts at ECM terminal A2 for at least 30 seconds at 550-650 RPM.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
Test Number 1) This confirms Code 23 and fault are present.
Test Number 2) This test determines if sensor signal line is shorted to ground.
Test Number 3) See THROTTLE POSITION SENSOR in N - REMOVE/INSTALL/OHAUL.