Cat 303C CR Serial No BXT41x. Auto Idle used to work as intended; machine no longer idles down during inactivity. This machine has an on/off rocker switch for auto idle located on the right hand operator’s console near the throttle potentiometer. The troubleshooting procedure describes how to check out the entire control system, concluding that, if everything checks out, replace the $600 controller module. My issue is that the auto idle on/off switch does not appear in the wiring diagram, and I cannot find a separate schematic that shows it, so it is not clear how it disables auto idle. Furthermore, the troubleshooting procedure includes checks of the throttle potentiometer circuit, which is obviously functioning properly because I have full manual control of engine speed via the speed knob. My current plan, when I have an opportunity to spend more time with it, is to verify that the implement pressure switch and the travel pressure switch both appear open at the controller module pins, to rule out that neither of them is shorted closed either within the switch or in the wiring harness. Anyone here been through this, or have guidance for me? TIA
What's the reference of the electrical schematic you are using.? I see RENR9618-00 and the AEC switch is shown as an attachment (option)
I haven’t been able to find what I consider a proper schematic. The illustration reference is g03642871. There is also a reference at the top of the page of i05730487. (I’m a newbie when it comes to Cat service documentation.) My manual was purchased from a 3rd party because my request for a SIS subscription access is being ignored by my dealer. Maybe this is part of my problem.
Check your messages. Schematic on the way.
I want to again thank you for your invaluable assistance. It appears that the switch for auto idle doesn’t actually enable it; instead, when in the “off” position, it disables auto idle by providing a ground to tell the control module that the hydraulics are under load. This gives me confidence in my planned troubleshooting approach.