Chart A-4 WOT Enrichment Circuit Check

Chart A-4:

Chart A-4 Wiring Diagram:

CIRCUIT DESCRIPTION:

The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle valve angle. Signal voltage will vary from less than O.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 used by the ECM for fuel control and for many of the ECM controlled outputs.

DIAGNOSTIC AIDS:

A "Scan" tool displays throttle position in volts. Closed throttle voltage should be less than O.8 volts. TPS voltage should increase at a steady rate as throttle is moved to WOT.