The Engine Control Module (ECM) detects specific conditions that activate or override the Idle Shutdown Timer. The key scenarios are as follows:
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Conditions Detected by the ECM:
- Idle Stop Override Parameter Settings:
- The Allow Idle Stop Override parameter is programmed to “Yes,” and the brake switch or clutch switch changes status.
- The parameter is set to J1587 Outside Temperature Based or Outside Temperature Based:
- The outside temperature is higher than the maximum programmed temperature.
- The outside temperature is lower than the minimum programmed temperature.
- Idle Shutdown Timer Conditions:
- The idle stop timer expired less than 90 seconds ago.
- The idle time parameter is programmed to at least 3 minutes.
Purpose of the Idle Shutdown Timer:
The Idle Shutdown Timer is designed to improve fuel efficiency by limiting engine idling time. It can be programmed for durations ranging from 3 minutes to 1440 minutes, based on customer preferences.
The timer activates when all of the following conditions are met:
- Vehicle speed is zero.
- The engine is not in cold mode or dedicated PTO mode.
- The engine is not under load.
Timer Reset and Warning Signals:
- The timer resets if the vehicle moves or the accelerator pedal is quickly pressed and released.
- 90 seconds before the programmed idle time ends, the Check Engine Light will flash rapidly.
- During this warning period, the timer is disabled if:
- The clutch pedal is pressed.
- The service brake pedal is pressed.
Possible Causes of Idle Stop Override Issues:
- ECM Programming Issues:
- Incorrect parameter settings for the Idle Stop Override or Idle Shutdown Timer.
- Sensor or Switch Errors:
- Faulty clutch or brake pedal sensors.
- Malfunctioning vehicle speed sensor, resulting in incorrect speedometer readings.
- Wiring Issues:
- Damaged or faulty wiring in the clutch sensor or brake sensor locations.
- Errors in the PTO switch or wiring harness.
Solution Steps:
- Verify the ECM programming:
- Ensure that the Allow Idle Stop Override and Idle Shutdown Timer parameters are correctly configured.
- Inspect and test the following components:
- Clutch pedal sensor and brake pedal sensor for errors or misalignment.
- Vehicle speed sensor for accurate operation and calibration.
- PTO switch and associated wiring for continuity and correct function.
- Check for wiring harness issues:
- Examine connections and wires leading to the clutch and brake sensors for damage or loose connections.