Cummins ISB CM550 (1990-94) Fault Code: 387 PID: 91 SPN: FMI: 3 Accelerator Position Sensor Circuit

Circuit Description
The accelerator pedal assembly with accelerator position sensor relays the accelerator
percentage requested by the operator to the electronic control module (ECM). Percent accelerator
is used by the ECM to determine fueling. In order for the accelerator position sensor to function
properly, it is necessary that a good +5-VDC supply voltage is available.

Component Location
The accelerator position sensor is located on the accelerator pedal inside the vehicle cab.