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Monitor Description

The ECM detects idle speed and idle air flow amount for Idle Speed Control (ISC). The ECM concludes that the ISC is malfunctioning if: 1) the learned value of the ISC remains at the maximum or minimum 5 times or more during a drive cycle, and 2) while driving at 6 mph (10 km/h) or more, the actual idle rpm varies from the target rpm by between 100 to 150 rpm 5 times or more during a drive cycle.

Example:

If the actual idle rpm varies from the target idle rpm by more than 100 rpm* 5 times during a drive cycle, the ECM will turn on the MIL and a DTC is set.

HINT:

*: rpm threshold varies with engine load.

Fig 1: Idle Speed Graph (RPM And Learned Value)
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