FAULT CODE 431 (ISS)

Idle Validation Switch Circuit

Overview

ISS

CODE REASON EFFECT
Fault Code: 431
PID: P091
SPN: 91
FMI: 2
LAMP: Yellow
SRT: 00-611

Voltage detected simultaneously on both the idle validation off-idle and idle signal pins 6 and 9 of the OEM harness connector or no voltage detected at either pin.

None on performance.

Idle Validation Switch Circuit

SMALL | MEDIUM | LARGE

Circuit Description

The idle validation switch is used by the electronic control module (ECM) to indicate when the accelerator pedal is released (on-idle) or depressed (off-idle). The switch is adjusted at the factory to switch from on-idle to off-idle at the correct accelerator pedal position.

Component Location

The integrated sensor/switch is located on the accelerator pedal assembly.

Shop Talk

  • This fault code is usually caused by a loose connection, an accelerator pedal that is not calibrated, or an idle validation switch that is wired wrong.
  • If all wiring and sensor checks are good, replace the idle validation switch circuit wires, between the accelerator pedal and ECM, with new wires. Run the wires through or around the bulkhead without using the bulkhead connector. Test the truck with the test wires in place. If the fault clears, replace the OEM harness. Seal the openings in the bulkhead around the connector and wires to prevent toxic and noxious fumes from entering the cab.

Note: Verify that the three idle validation switch circuit wires are twisted together.

  • The ECM and accelerator pedal assembly must be electrically calibrated to each other for proper engine response. The ECM and accelerator pedal assembly must be calibrated when an accelerator pedal is initially installed, replaced, when an ECM is replaced, when a new calibration is downloaded to the ECM, and when the accelerator pedal wiring is disconnected while the vehicle keyswitch is ON.
  • With keyswitch ON, gradually push the accelerator to the floor and release. Depress and release the accelerator pedal three times. This procedure will recalibrate the ECM and accelerator pedal.

Cautions and Warnings

 WARNING 

Set the service brake using the trailer brake hand valve. Make sure there is enough air pressure to activate the brake pressure switch. Securely chock the wheels. Truck movement during troubleshooting can cause severe equipment damage, personal injury, or death.

 CAUTION 

To reduce the possibility of damaging the 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 following test leads when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead
Part Number 3823995 – male Weather-Pack test lead
Part Number 3823996 – female Weather-Pack test lead.

 CAUTION 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3823995 – male Weather-Pack test lead
Part Number 3823996 – female Weather-Pack test lead.

 CAUTION 

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

 CAUTION 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822917 – female Deutsch test lead.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the accelerator pedal.  
  STEP 1A. Verify the integrated sensor switch is connected to the OEM harness. Integrated sensor switch connected
  STEP 1B. Inspect the harness and integrated sensor switch connector pins. No damaged pins
  STEP 1C. Check for an open circuit. Less than 125 ohms
  STEP 1D. Check for a short circuit from pin to pin. More than 100k ohms
STEP 2. Check the OEM harness.  
  STEP 2A. Inspect the OEM harness and ECM connector pins. No damaged pins
  STEP 2B. Check for an open circuit. Less than 125 ohms
  STEP 2C. Check for a short circuit from pin to pin. More than 100k ohms
STEP 3. Check the ECM response.  
  STEP 3A. Verify ECM response. Fault Code 431 inactive
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 431 inactive
  STEP 4B. Clear the inactive fault codes. All fault codes cleared


Guided Step 1 – Check the accelerator pedal.

Guided Step 1A – Verify the integrated sensor switch is connected to the OEM harness.

Conditions

  • Turn keyswitch OFF.

Action

Verify the integrated sensor switch is connected to the OEM harness.

SMALL | MEDIUM | LARGE
OK NOT OK

Integrated sensor switch connected

Integrated sensor switch disconnected from pedal. Connect the OEM harness to the integrated sensor switch. Refer to the OEM troubleshooting and repair manual.

Guided Step 1B – Inspect the harness and integrated sensor switch connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness from the integrated sensor switch.
  • Flush and clean the connector pins using electronic contact cleaner, Part Number 3824510.

Action

  • Loose connector
  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Moisture in or on the connector
  • Missing or damaged seals
  • Dirt or debris in or on the connector pins
  • Connector shell broke
  • Wire insulation damage
  • Damaged locking tab connector.
OK NOT OK

No damaged pins

Repair damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Replace the integrated sensor switch if the connector pins are damaged. Refer to the OEM troubleshooting and repair manual.
  • Replace the integrated sensor switch connector if it is oversize or damaged. Refer to the OEM troubleshooting and repair manual.
  • Install the appropriate connector seal if it is damaged or missing. Refer to the OEM troubleshooting and repair manual.

 WARNING 

Set the service brake using the trailer brake hand valve. Make sure there is enough air pressure to activate the brake pressure switch. Securely chock the wheels. Truck movement during troubleshooting can cause severe equipment damage, personal injury, or death.
 CAUTION 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3823995 – male Weather-Pack test lead
Part Number 3823996 – female Weather-Pack test lead.

Guided Step 1C – Check for an open circuit.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness from the integrated sensor switch.

Action

  • Measure the resistance from the idle signal pin to the return wire pin on the integrated sensor switch with the pedal released.
  • Measure the resistance from the off-idle signal pin to the return wire pin on the integrated sensor switch with the pedal depressed.
SMALL | MEDIUM | LARGE
OK NOT OK

Less than 125 ohms

Replace the integrated sensor switch. Refer to the OEM troubleshooting and repair manual.

 WARNING 

Set the service brake using the trailer brake hand valve. Make sure there is enough air pressure to activate the brake pressure switch. Securely chock the wheels. Truck movement during troubleshooting can cause severe equipment damage, personal injury, or death.
 CAUTION 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3823995 – male Weather-Pack test lead
Part Number 3823996 – female Weather-Pack test lead.

Guided Step 1D – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness from the integrated sensor switch.

Action

  • Measure the resistance from the idle signal pin to the off-idle signal pin on the integrated sensor switch with the pedal released and depressed.
SMALL | MEDIUM | LARGE
OK NOT OK

More than 100k ohms

Replace the integrated sensor switch. Refer to the OEM troubleshooting and repair manual.


Guided Step 2 – Check the OEM harness.

 CAUTION 

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

Guided Step 2A – Inspect the OEM harness and ECM connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness connector from the ECM.
  • Flush and clean the connector pins using electronic contact cleaner, Part Number 3824510.

Action

  • Loose connector
  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Moisture in or on the connector
  • Missing or damaged seals
  • Dirt or debris in or on the connector pins
  • Connector shell broke
  • Wire insulation damage
  • Damaged locking tab connector.
OK NOT OK

No damaged pins

Repair damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair the OEM harness. Refer to the OEM troubleshooting and repair manual.
  • Replace the OEM harness. Refer to the OEM troubleshooting and repair manual.
  • Repair the bulkhead connector. Refer to Procedure 019-208.
  • Replace the ECM. Refer to Procedure 019-031.
  • Replace the o-ring on the 28-pin connector if it is damaged or missing. Refer to Procedure 019-203.

 WARNING 

Set the service brake using the trailer brake hand valve. Make sure there is enough air pressure to activate the brake pressure switch. Securely chock the wheels. Truck movement during troubleshooting can cause severe equipment damage, personal injury, or death.
 CAUTION 

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

Guided Step 2B – Check for an open circuit.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness connector from the ECM.
  • Connect the OEM harness to the integrated sensor switch.

Action

  • Measure the resistance from pin 6 of the OEM harness to pin 10 of the OEM harness with the accelerator pedal released.
  • Measure the resistance from pin 9 of the OEM harness to pin 10 of the OEM harness with the accelerator pedal depressed.
SMALL | MEDIUM | LARGE
OK NOT OK

Less than 125 ohms

Repair or replace the OEM harness. Refer to the OEM troubleshooting and repair manual.

 WARNING 

Set the service brake using the trailer brake hand valve. Make sure there is enough air pressure to activate the brake pressure switch. Securely chock the wheels. Truck movement during troubleshooting can cause severe equipment damage, personal injury, or death.
 CAUTION 

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

Guided Step 2C – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness connector from the ECM.
  • Disconnect the OEM harness from the integrated sensor switch.
  • Set cab switches to the NEUTRAL or OFF position.
  • Set the service brake.
  • Disconnect the clutch switch from the OEM harness.
  • Disconnect the AC pressure switch.
  • Diagnostic switch not in diagnostic mode.

Action

  • Measure the resistance from pin 6 of the OEM harness to all other pins of the OEM harness.
  • Measure the resistance from pin 9 of the OEM harness to all other pins of the OEM harness.
SMALL | MEDIUM | LARGE
OK NOT OK

More than 100k ohms

Repair or replace the OEM harness. Refer to the OEM troubleshooting and repair manual.


Guided Step 3 – Check the ECM response.

 CAUTION 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822917 – female Deutsch test lead.

 CAUTION 

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

Guided Step 3A – Verify ECM response.

Conditions

  • Disconnect the OEM harness connector to the ECM.

Action

  • Use Part Number 3822917, as a jumper wire, from pin 10 to pin 6 in the OEM port of the ECM.
  • Turn keyswitch ON.
SMALL | MEDIUM | LARGE
OK NOT OK

Fault Code 431 inactive

Replace the ECM. Refer to Procedure 019-031.


Guided Step 4 – Clear the fault codes.

Guided Step 4A – Disable the fault code.

Conditions

  • Connect all the components.

Action

  • Turn the keyswitch ON and completely depress and release the accelerator pedal three times.
  • Turn the keyswitch OFF for 5 seconds.
  • Start the engine and let it idle for 1 minute.
  • Verify that Fault Code 431 is inactive.
OK NOT OK

Fault Code 431 inactive

Return to troubleshooting steps or contact your nearest Cummins Authorized Repair Location if all steps have been completed and rechecked.

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all the components.

Action

  • Erase the inactive fault codes using INSITE™ electronic service tool.
OK NOT OK

All fault codes cleared

Troubleshoot any remaining active fault codes.

Repair complete

Appropriate troubleshooting chart

Last Modified:  26-Aug-2004