Circuit Description

WARNING: This page is about a different car, the 2002 Isuzu Trooper. However, it is still accessible from the selected car via links, so may be relevant.

Throttle Position Sensor 1 (TPS1) circuit provides a voltage signal relative to throttle valve position. Throttle valve angle will vary from about 8 percent at closed throttle to about 92 percent at wide open throttle. PCM detects a continuous short to ground or high resistance in either circuit or sensor. Mass Air Flow (MAF) sensor measures amount of air which passes through it into the engine during a given time. PCM uses MAF information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle. MAF sensor produces a frequency signal which can be monitored using a scan tool. Frequency will vary within about 4-7 grams/sec. at idle to about 25-40 grams/sec. at maximum engine load. DTC detects if system is in Power Management Mode (Fail Safe Mode).

When DTC sets, PCM illuminates MIL as soon as fault was detected. PCM calculates an air flow value based on idle air control valve position, throttle position, RPM and barometric pressure. PCM will store conditions present when DTC was set as freeze frame data in the FAILURE RECORDS data.

PCM will turn MIL off on third consecutive trip cycle during which diagnostic runs and fault is no longer recognized. A history DTC will clear after 40 consecutive trip cycles during which diagnostic runs and fault is no longer recognized. DTC can be cleared with scan tool, or by disconnecting battery voltage feed to PCM.