Toyota Tundra Service Manual: Definition Of Terms




Monitor Description

Description of what ECM monitors and how it detects malfunctions (monitoring purpose and details).

Related DTCs

Group of diagnostic trouble codes output by ECM based on same malfunction detection logic.

Typical Enabling Conditions

Preconditions that allow ECM to detect malfunctions.

With all preconditions satisfied, ECM stores DTCs when monitored value(s) exceeds malfunction threshold(s).

Sequence of Operation

Order of monitor priority, applied if multiple sensors and components involved in single malfunction detection process.

Each sensor and component monitored in turn, when previous detection operation completed.

Required Sensor/Components

Sensors and components used by ECM to detect each malfunction.

Frequency of Operation

Number of times ECM checks for each malfunction during each driving cycle.

"Once per driving cycle" means ECM only performs checks for that malfunction once during single driving cycle.

"Continuous" means ECM performs checks for that malfunction whenever enabling conditions met.


Minimum time for which ECM must detect continuous deviation in monitored value(s) in order to store a DTC. Timing begins when Typical Enabling Conditions met.

Malfunction Thresholds

Value beyond which ECM determines malfunctions exist and stores DTCs.

MIL Operation

Timing of MIL illumination after malfunction detected.

"Immediate" means ECM illuminates MIL as soon as malfunction detected.

"2 driving cycles" means ECM illuminates MIL if same malfunction detected second time during next sequential driving cycle.

    Data List / Active Test

    Diagnosis System

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