IAFM T/MAP Circuit

The T/MAP on the IAFM engines (4.3L, 5.0L and 5.7L MPI) works the same way as an 8.1L MAP except the IAFM engines incorporate the IAT in the MAP sensor. The MAP and the IAT share the sensor return (ground). IAT functionality is discussed later in this book.

Throttle Position Sensor (TPS)

The Throttle Position Sensor (TPS) is a potentiometer connected to the throttle shaft on the throttle body. At closed throttle the voltage output is low. Thevoltage increases proportionately as the throttle is opened. The ECM uses the TPS signal to control the idle air controller and acceleration enrichment.

The following information is available with the scan tool: TPS voltage, TPS percent throttle, and Closed throttle (yes/no). TPS voltage is the actual input tothe ECM. TPS Percent is a calculated value that is the difference between actual TPS voltage and learned TPS minimum. Closed throttle is a calculated value based off of TPS percent. If TPS percent is below 2%, then closed throttle is “yes”. Above 2% closed throttle is “no”.

MEFI 3 and 4 TPS’s are non-adjustable.