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Electronic Control System Gas Plus Engines – FAULT CODE 131

Accelerator Pedal Position Sensor Circuit – Shorted High

Overview

CODE REASON EFFECT
Fault Code: 131
PID: P091
SPN: 091
FMI: 3
LAMP: Red
SRT: 

The acceleration pedal position sensor circuit – shorted high. High voltage detected on the accelerator pedal position signal at the ECM.

Engine idles when the idle validation switch indicates idle and ramps up to a default set speed when the idle validation switch indicates off idle.

Accelerator Pedal Position Sensor and Idle Validation Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The accelerator pedal position sensor sends a signal to the electronic control module (ECM), when the driver depresses the accelerator pedal, to determine the accelerator pedal position.

Component Location

The accelerator pedal position sensor is located on the accelerator pedal.

Shop Talk

This signal is a 0- to 5.0-VDC signal from the foot pedal potentiometer to the ECM. At a foot pedal position of 100 percent closed, a 5.0-VDC signal will be output from the pedal. The wiring between the accelerator pedal and the OEM connector will be a twisted pair.

Cautions and Warnings

 CAUTION 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
 CAUTION 

To reduce the possibility of pin and harness damage, use the appropriate test lead when taking a measurement.
 CAUTION 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead
Part Number 3823993 – male Deutsch test lead
Part Number 3823996 – female Weather-Pack test lead.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Check for sensor supply fault code. Fault Code 387 active?
  STEP 1B. Check for an inactive fault code. Fault Code 131 inactive?
STEP 2. Check the accelerator pedal and circuit.  
  STEP 2A. Inspect the accelerator pedal and connector pins. Dirty or damaged pins?
  STEP 2B. Check the accelerator pedal supply voltage and return circuit. 4.5 to 5.25 VDC?
  STEP 2C. Check the circuit response. Fault Code 132 active and Fault Code 131 inactive?
  STEP 2D. Check the fault codes and verify accelerator pedal condition. Fault Code 132 active?
STEP 3. Check the engine control module and engine harness.  
  STEP 3A. Inspect the engine control module and engine harness connector pins. Dirty or damaged pins?
  STEP 3A-1. Check for an open circuit in the engine harness and OEM harness.
  STEP 3A-2. Check for a pin to pin short circuit in the engine harness and OEM harness.
  STEP 3B. Check for an inactive fault code. Fault Code 131 inactive?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 131 inactive?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Check for sensor supply fault code.

Conditions

  • Turn keyswitch ON
  • Connect the INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 387 active?
YES NO
No Repair No Repair
Fault Code 387

Guided Step 1B – Check for inactive fault code.

Conditions

  • Turn keyswitch ON
  • Connect the INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 131 inactive?
YES NO
No Repair No Repair

Guided Step 2 – Check the accelerator pedal and circuit.

Guided Step 2A – Inspect the accelerator pedal and connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the accelerator pedal from the OEM harness.

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Wire insulation damage
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Connector shell broken
  • Dirt or debris in or on the connector pins.

For general inspection techniques, refer to Component Connector and Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

A defective connection has been detected in the sensor or harness connector.

Repair or replace the engine harness or OEM harness.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair or replace the OEM harness. Refer to the OEM troubleshooting and repair manual.
  • Repair the engine harness. Refer to Procedure 019-201.
  • Replace the engine harness. Refer to Procedure 019-043.
 No Repair

Guided Step 2B – Check the accelerator pedal supply voltage and return circuit.

Conditions

  • Turn keyswitch OFF
  • Disconnect the accelerator pedal from the OEM harness
  • Turn keyswitch ON.

Action

  • Measure the voltage between the accelerator pedal SUPPLY pin and the accelerator pedal RETURN pin at accelerator pedal connector of the OEM harness.

Refer to the circuit diagram or wiring diagram for connector pin identification.

4.5 to 5.25 VDC?
YES NO
No Repair No Repair

Guided Step 2C – Check the circuit response.

Conditions

  • Turn keyswitch OFF
  • Disconnect the accelerator pedal from the OEM harness
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes .

Fault Code 132 active and Fault Code 131 inactive?
YES NO
No Repair No Repair

Guided Step 2D – Check the fault codes and verify accelerator pedal condition.

Conditions

  • Turn keyswitch OFF
  • Connect the accelerator pedal to the OEM harness
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes .

Fault Code 132 active?
YES NO

A defective accelerator pedal has been detected. Contact the appropriate OEM or dealership for repair instructions.

Replace the accelerator pedal. Refer to the OEM troubleshooting repair manual.

 No Repair

Guided Step 3 – Check the engine ECM and engine harness.

Guided Step 3A – Inspect the ECM and engine harness connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect engine harness connector 2 from the ECM.

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Wire insulation damage
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Connector shell broken
  • Dirt or debris in or on the connector pins.

For general inspection techniques, refer to Component Connector and Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

A defective connection has been detected in the ECM or harness connector.

Repair or replace the engine harness.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair the engine harness. Refer to Procedure 019-201.
  • Replace the engine harness. Refer to Procedure 019-043.
 No Repair

Guided Step 3A-1 – Check for an open circuit in the engine harness and OEM harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 2 from the ECM
  • Disconnect the accelerator pedal from the OEM harness.

Action

  • Measure the resistance between the engine harness ECM connector RETURN pin and the OEM harness accelerator pedal connector RETURN pin.

Refer to the circuit diagram or wiring diagram for connector pin identification.

For general resistance measurement techniques, refer to Resistance Measurements Using a Multimeter and Wiring Diagram, Procedure 019-360.

Less than 10 ohms?
YES NO
No Repair

An open circuit has been detected in the engine harness or the OEM harness.

Troubleshoot each harness connected is series to determine which contains the shorted signal circuit.

Repair or replace the engine harness or OEM harness.

  • Repair or replace the OEM harness. Refer to the OEM troubleshooting and repair manual.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3A-2 – Check for a pin to pin short circuit in the engine harness and OEM harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 1 and connector 2 from the ECM
  • Disconnect the accelerator pedal from the OEM harness.

Action

  • Measure the resistance between the accelerator pedal SIGNAL pin in the engine harness ECM connector 2 and all other pins in the engine connector 2.
  • Measure the resistance between the accelerator pedal SIGNAL pin in the engine harness ECM connector 2 and all other pins in the engine connector 1.

Refer to the circuit diagram or wiring diagram for connector pin identification.

For general resistance measurement techniques, refer to Resistance Measurements Using a Multimeter and Wiring Diagram, Procedure 019-360.

Greater than 100k ohms?
YES NO
No Repair

A pin to pin short circuit on the SIGNAL line has been detected in the engine harness or the OEM harness.

Troubleshoot each harness connected is series to determine which contains the shorted signal circuit.

Repair or replace the engine harness or OEM harness.

  • Repair or replace the OEM harness. Refer to the OEM troubleshooting and repair manual.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3B – Check for an inactive fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 131 inactive?
YES NO
No Repair

Replace the ECM. Call for pre-authorization. Refer to Procedure 019-031.

Guided Step 4 – Clear the fault codes.

Guided Step 4A – Disable the fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Start the engine and let it idle for one minute
  • Use INSITE™ electronic service tool to verify the fault code is inactive.

Fault Code 131 inactive?
YES NO
No Repair No Repair

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

  • Use INSITE™ electronic service tool to erase the inactive fault codes.

All fault codes cleared
YES NO
No Repair No Repair
Repair complete
Appropriate troubleshooting charts
Last Modified:  06-Aug-2004
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