Circuit DescriptionThe idle validation switch (IVS) is used by the electronic control module (ECM) to indicatewhen the accelerator pedal is released (on-idle) or depressed (off-idle). The switch is adjustedby the accelerator pedal manufacturers to switch from on-idle to off-idle at the correctaccelerator pedal position. NOTE: The connector pin letters shown for the accelerator pedal wiring in thesetroubleshooting steps are examples of representative sensors. The connector pin assignmentscan vary with the equipment manufacturer, but the base troubleshooting logic will still apply. Component LocationThe idle validation switch is located on the accelerator pedal assembly. Shop TalkThis fault code is usually caused by...

Circuit DescriptionThe idle validation switch (IVS) is used by the electronic control module (ECM) to indicatewhen the accelerator pedal is released (on-idle) or depressed (off-idle). The switch is adjustedby the accelerator pedal manufacturers to switch from on-idle to off-idle at the correctaccelerator pedal position. NOTE: The connector pin letters shown for the accelerator pedal wiring in thesetroubleshooting steps are examples of representative sensors. The connector pin assignmentscan vary with the equipment manufacturer, but the base troubleshooting logic will still apply. Component LocationThe idle validation switch is located on the accelerator pedal assembly. Shop TalkThis fault code is usually caused by...

Circuit DescriptionThe accelerator pedal assembly relays the accelerator percentage requested by the operatorto the electronic control module (ECM). Percent accelerator is used to determine fueling. Theaccelerator position sensor and the idle validation switch on the accelerator pedal are adjustedat the factory to provide the correct output signals. NOTE: The connector pin letters shown for the accelerator pedal wiring in thesetroubleshooting steps are examples of representative sensors. The connector pin assignmentscan vary with the equipment manufacturer, but the base troubleshooting logic will still apply. Component LocationThe accelerator position sensor and the idle validation switch are located on the acceleratorpedal in the...

Circuit DescriptionThe intake manifold pressure sensor monitors intake manifold pressure and passes information to theelectronic control module (ECM) through the engine harness. If intake manifold pressure becomes toohigh, it will cause a derate condition. Component LocationThe intake manifold pressure sensor is located in the side of the intake manifold, just to the right ofthe fuel filter. Shop TalkThe ECM checks for this fault only at idle speed. If the intake manifold pressure shows too high of avalue at this time, the ECM will log a fault code. Cummins ISB CM550 (1990-94) Fault Code: 432 PID: 91 SPN: 91 FMI: 13...

Circuit DescriptionThe ECM receives constant voltage from the batteries through the unswitched battery wiresthat are connected directly to the positive (+) battery post. There are three in-line 7.5-ampfuses and one 20-amp fuse in the unswitched battery wires to protect the engine harness fromoverheating. The ECM receives switched battery input through the vehicle keyswitch wire,when the vehicle keyswitch is turned on. Component LocationThe ECM is connected to the battery by the engine harness. This direct link provides aconstant power supply for the ECM. The location of the battery will vary with the equipmentmanufacturer. See the equipment manufacturer repair manual. Shop TalkNOTE:...