Caterpillar C9 Engine 01 71-0 Idle Stop Override Solution

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:

  1. 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.
  2. 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:

  1. ECM Programming Issues:
    • Incorrect parameter settings for the Idle Stop Override or Idle Shutdown Timer.
  2. Sensor or Switch Errors:
    • Faulty clutch or brake pedal sensors.
    • Malfunctioning vehicle speed sensor, resulting in incorrect speedometer readings.
  3. Wiring Issues:
    • Damaged or faulty wiring in the clutch sensor or brake sensor locations.
    • Errors in the PTO switch or wiring harness.

Solution Steps:

  1. Verify the ECM programming:
    • Ensure that the Allow Idle Stop Override and Idle Shutdown Timer parameters are correctly configured.
  2. 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.
  3. Check for wiring harness issues:
    • Examine connections and wires leading to the clutch and brake sensors for damage or loose connections.