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.

ION Sensing module has function to energize and de-energize primary ignition coil in response to signals from PCM. PCM controls ignition timing and dwell. This diagnosis detects open or short circuit(s) in ignition Electronic Spark Timing (EST) line by monitoring EST signals. A failure determination is made when signal voltage remains higher or lower than threshold value for corresponding fault code beyond a predetermined time period. When PCM detects a problem on an EST control circuit it will set a corresponding DTC (P0351-P0356).

When DTC sets, PCM illuminates MIL as soon as fault was detected. 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.