Cummins ISB4.5 CM2150 Fault Code: 131 PID: 91 SPN: 91 FMI: 3 Accelerator Pedal or Lever Position Sensor 1 Circuit – Voltage Above Normal or Shorted to High Source.

Circuit Description
The accelerator position sensor is a Hall effect sensor attached to the accelerator pedal. The accelerator position sensor varies the signal voltage to the engine control module (ECM) as the accelerator pedal is depressed and released. Low signal voltage is received by the ECM when the accelerator pedal is at 0 percent. A high signal voltage is received by the ECM when the accelerator pedal is at 100 percent. The accelerator pedal position circuit contains an accelerator pedal position 5 volt supply, accelerator pedal position return, and accelerator pedal position signal.

The accelerator pedal contains two position sensors. These position sensors are used to measure the throttle position. Both position sensors receive a 5 volt supply from the ECM. A corresponding signal voltage based on the position of the accelerator pedal is then received from the ECM. The signal voltage for accelerator position 1 is twice as much as the signal voltage from the accelerator position 2.

When the ECM senses a signal voltage higher than the normal operating range of the sensor, this fault code is set.

Component Location
The accelerator pedal or lever position sensor is located on the accelerator pedal or lever. Refer to the original equipment manufacturer (OEM) troubleshooting and repair manual.

Action Taken When the Fault Code is Active
The ECM illuminates the red STOP ENGINE light and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the red STOP ENGINE light immediately after the diagnostic runs and passes.
-The ECM will turn off the MIL after three consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and MIL can also be cleared with INSITE™ electronic service tool.

Shop Talk
Newer engines use two throttle position sensors to determine the throttle position. Older throttle pedals used a single throttle position sensor and an idle validation switch. If Fault Codes 132 and 1241 are active when the accelerator pedal is in the idle position, and Fault Code 132 goes inactive, and Fault Code 1239 goes active when the throttle is depressed, the incorrect throttle pedal has been installed in the vehicle. A throttle pedal with two acceleration position sensors must be installed.

If troubleshooting an intermittent accelerator problem:

The accelerator pedal or lever position sensor signal voltage can be monitored with INSITE™ electronic service tool, while flexing the harness to locate the intermittent connection. Intermittent connections will show up as abrupt changes in signal voltage displayed by INSITE™ electronic service tool.

Possible Causes
-Accelerator pedal or lever position signal circuit shorted to battery or (+) 5 volt supply
-Open accelerator pedal return circuit in the harness or connections
-Accelerator supply shorted to battery
-Failed accelerator pedal or lever position sensor.

*The three wires in the accelerator position sensor circuit must be twisted together.