Chart A-4, TPS Wide-Open-Throttle Enrichment Circuit Check

The Throttle Position Sensor (TPS) provides a voltage signal that changes, relative to the throttle valve. Signal voltage will vary from less than .8 volts at idle to about 4.5 volts at wide open throttle (WOT). The idle switch provides the ECM with information used to decide closed loop operation and indicates the off-idle condition to the ECM. This switch is normally closed at idle and opens above 1800 RPM, which is then the off-idle condition. The TPS signal is one of the most important inputs by the ECM for fuel control and for many of the ECM controlled outputs.