My 2000 Freightliner FLD, powered by a Cat C12 engine, has been a reliable workhorse. Recently, the cruise control stopped functioning. I’ve started troubleshooting and even acquired a comprehensive Freightliner FLD manual.
Here’s what I’ve found so far:
- The cruise control system includes an On/Off switch and a Set/Resume/Accel/Decel switch.
- The cruise control doesn’t engage in either Park or Drive.
- The Engine Control Module (ECM) Pin 790 supplies 12V to the cruise control circuitry.
- There’s 12V at the input of both the On/Off and Set/Resume switches.
- The clutch pedal switch lacks 12V input on all three terminals, despite its supposed connection to ECM Pin 790.
- Attempting to bypass the clutch switch by connecting 12V directly from the cruise On/Off switch proved unsuccessful.
I need help understanding the system better to fix this issue. Specifically:
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System Schematic and Sensor Input: Does anyone have a schematic for the cruise control system on a 2000 Freightliner FLD? Knowing which sensors (clutch, brake, park) are involved and how they interact is crucial. Understanding the signal flow would help pinpoint the problem area.
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Brake Switch Identification: Is the brake switch that disengages the cruise control the same switch that activates the brake lights? Or is there a separate dedicated cruise control brake switch?
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Brake Switch Location: Where is the brake switch (or switches) located on a 2000 Freightliner FLD? Knowing its location will allow for easier testing and inspection.
Any insights or advice regarding these questions would be greatly appreciated.
