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FAULT CODE 422

Coolant Level Sensor Circuit

Overview

CODE REASON EFFECT
Fault Code: 422
PID: P111
SPN: 111
FMI: 2
LAMP: Yellow
SRT: 00-610

Voltage detected simultaneously on both the coolant level high and low signal pins 18 and 9 of sensor harness connector or no voltage detected on both pins.

No engine protection for coolant level.

Coolant Level Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The coolant level sensor monitors the coolant level within the coolant system and passes information to the electronic control module (ECM) through the sensor harness. This sensor is very complex.

Note: Do not use a multimeter to check the coolant level sensor.

If the radiator coolant level drops below a certain level, a progressive power derate with increasing time after alert will occur. The coolant level sensor is an OEM-controlled sensor. Actual OEM wiring can vary from the Robert Shaw sensor shown. Consult your OEM for specific pinouts for the OEM side of the 9-pin Deutsch connector.

Component Location

The coolant level sensor is located in the radiator top tank or surge tank.

Cautions and Warnings

 WARNING 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
 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 3822917 – female Deutsch/AMP/Metri-Pack test lead
Part Number 3823993 – male Deutsch test lead
Part Number 3823994 – female Deutsch 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.
 CAUTION 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3823994 – female Deutsch test lead.
 CAUTION 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3823993 – male Deutsch test lead
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead
Part Number 3822917 – female Deutsch/AMP/Metri-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.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check for multiple fault codes and presence of coolant level switch.  
  STEP 1A. Read the fault codes. Fault Codes 123, 141, 145, 154, 222, and 352 inactive
  STEP 1B. Check if the vehicle has a coolant level switch. Coolant level switch present
  STEP 1C. Check if a shorting plug is installed. Shorting plug installed
STEP 2. Check for proper ECM response.  
  STEP 2A. Check ECM response. Fault Code 422 inactive
  STEP 2B. Check for proper ECM response. Fault Code 422 inactive
STEP 3. Check the sensor harness.  
  STEP 3A. Inspect the sensor harness and ECM connector pins. No damaged pins
  STEP 3B. Read the fault codes. Fault Code 422 active
  STEP 3C. Check for an open circuit. Less than 10 ohms
  STEP 3D. Check for a short circuit to ground. More than 100k ohms
  STEP 3E. Check for a short circuit from pin to pin. More than 100k ohms
STEP 4. Check the coolant level sensor.  
  STEP 4A. Inspect the coolant level sensor and the OEM harness connector pins. No damaged pins
  STEP 4B. Read the fault codes. Fault Code 422 active
STEP 5. Clear the fault codes.  
  STEP 5A. Disable the fault code. Fault Code 422 inactive
  STEP 5B. Clear the inactive fault codes. All fault codes cleared

Guided Step 1 – Check for multiple fault codes and presence of coolant level switch.

 WARNING 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
Guided Step 1A – Read the fault codes.

Conditions

  • Turn keyswitch ON.

Action

  • Read the fault codes using INSITE™.
OK NOT OK

Fault Codes 123, 141, 145, 154, 222, and 352 inactive

Fault Codes 123, 141, 145, 154, 222, and 352 active.

Fault Code Multiple A

 WARNING 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
Guided Step 1B – Check if the vehicle has a coolant level switch.

Conditions

  • Turn keyswitch OFF.

Action

Make sure the vehicle has a coolant level switch.
OK NOT OK

Coolant level switch present

Shorting plug installed.

 WARNING 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
Guided Step 1C – Check if a shorting plug is installed.

Conditions

  • Turn keyswitch OFF.

Action

Note: Check the OEM wiring from the shorting plug to the sensor harness connection for problems. Refer to the OEM and the sensor harness wiring diagrams.
OK NOT OK

Shorting plug installed

Install shorting plug.

Guided Step 2 – Check for proper ECM response.

 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 this test lead when taking a measurement:
Part Number 3822917 – female Deutsch test lead.
Guided Step 2A – Check ECM response.

Conditions

  • Disconnect sensor harness connector from ECM.
  • Connect jumper wire from pin 3 to pin 18 of the ECM sensor port. Use Part Number 3822917.
  • Connect jumper wire from pin 13 to pin 9 of the ECM sensor port. Use Part Number 3822917.
  • Turn keyswitch ON.

Action

  • Using electronic service tool, read the fault codes.
OK NOT OK

Fault Code 422 inactive

Replace ECM. Refer to Procedure 019-031.

 CAUTION 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3823994 – female Deutsch test lead.
Guided Step 2B – Check for proper ECM response.

Conditions

  • Connect sensor harness connector to ECM.
  • Connect jumper wire from A to C on 9-pin connector. Use Part Number 3823994.
  • Connect jumper wire from B to J on 9-pin connector. Use Part Number 3823994.
  • Turn keyswitch ON.

Action

  • Using an electronic service tool, read the fault codes.

Note: Read Shop Talk concerning OEM wiring from coolant level sensor to 9-pin Deutsch connector.
OK NOT OK

Fault Code 422 inactive. Check OEM wiring from coolant level sensor to OEM 9-pin connector for proper pinout, continuity, and shorts from pin to pin and to ground.

Refer to OEM wiring diagrams.

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

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

Conditions

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

Action

  • Bent or broken pins
  • Pushed back or expanded pins
  • Corroded pins
  • Moisture in or on the connector
  • Missing or damaged seals
  • Dirt or debris in or on the connector pins.
OK NOT OK

No damaged pins

Repair the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.
  • 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 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
Guided Step 3B – Read the fault codes.

Conditions

  • Connect the OEM harness to the coolant level sensor.
  • Connect the OEM harness to the sensor harness.
  • Connect the sensor harness connector to the ECM.
  • Turn keyswitch ON.

Action

  • Start the engine and let it idle for 1 minute.
  • Read the fault codes using INSITE™.
OK NOT OK

Fault Code 422 active

Repair complete.

 WARNING 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
 CAUTION 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3823993 – male Deutsch test lead
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
Guided Step 3C – Check for an open circuit.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness at the 9-pin Deutsch connector.
  • Disconnect the sensor harness connector from the ECM.

Action

  • Measure the resistance from pin 18 in the sensor harness connector to pin C on the sensor wiring harness side of the 9-pin connector.
  • Measure the resistance from pin 9 in the sensor harness connector to pin B on the sensor wiring harness side of the 9-pin connector.
  • Measure the resistance from pin 3 in the sensor harness connector to pin A on the sensor wiring harness side of the 9-pin connector.
  • Measure the resistance from pin 13 in the sensor harness connector to pin J on the sensor wiring harness side of the 9-pin connector.
SMALL | MEDIUM | LARGE
OK NOT OK

Less than 10 ohms

Repair or replace the sensor harness.

  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.

 WARNING 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
 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 3D – Check for a short circuit to ground.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness from the 9-pin Deutsch.
  • Disconnect the sensor harness connector from the ECM.
  • Disconnect all sensors, including coolant level sensor or shorting plug.

Action

  • Measure the resistance from pin 3 to engine block ground.
  • Measure the resistance from pin 9 to engine block ground.
  • Measure the resistance from pin 13 to engine block ground.
  • Measure the resistance from pin 18 to engine block ground.
SMALL | MEDIUM | LARGE
OK NOT OK

More than 100k ohms

Repair or replace the sensor harness.

  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.

 WARNING 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
 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 3E – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the OEM harness at the 9-pin Deutsch connector.
  • Disconnect the sensor harness connector from the ECM.
  • Disconnect all sensors, including coolant level sensor or shorting plug.

Action

  • Measure the resistance from pin 3 in the sensor harness connector to all other pins in the connector.
  • Measure the resistance from pin 9 in the sensor harness connector to all other pins in the connector.
  • Measure the resistance from pin 13 in the sensor harness connector to all other pins in the connector.
  • Measure the resistance from pin 18 in the sensor harness connector to all other pins in the connector.
SMALL | MEDIUM | LARGE
OK NOT OK

More than 100k ohms

Repair or replace the sensor harness.

  • Repair the sensor harness. Refer to Procedure 019-203.
  • Replace the sensor harness. Refer to Procedure 019-043.

Guided Step 4 – Check the coolant level sensor.

Guided Step 4A – Inspect the coolant level sensor and the OEM harness connector pins.

Conditions

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

Action

  • Bent or broken pins
  • Pushed back or expanded pins
  • Corroded pins
  • Moisture in or on the connector
  • Missing or damaged seals
  • Dirt or debris in or on the connector.
OK NOT OK

No damaged pins

Repair the 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 Procedure 019-201.
  • Replace the OEM harness. Refer to Procedure 019-071.
  • Replace the coolant level sensor. Refer to the OEM troubleshooting and repair manual.

 WARNING 

Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.
Guided Step 4B – Read the fault codes.

Conditions

  • Turn keyswitch ON.
  • Connect the OEM harness to the coolant level sensor.

Action

  • Read the fault codes using INSITE™.
OK NOT OK

Fault Code 422 active. Replace the coolant level sensor.

Repair complete.

Guided Step 5 – Clear the fault codes.

Guided Step 5A – Disable the fault code.

Conditions

  • Connect all the components.

Action

  • Start the engine and let it idle for 1 minute.
  • Verify Fault Code 422 is inactive.
OK NOT OK

Fault Code 422 inactive

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

Guided Step 5B – Clear the inactive fault codes.

Conditions

  • Connect all the components.

Action

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

All fault codes cleared

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting chart
Last Modified:  29-Oct-2003
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