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FAULT CODE 145

Coolant Temperature Sensor Circuit

Printable Version  Printable Version

Overview

CODE REASON EFFECT
Fault Code: 145
PID: P110
SPN: 110
FMI: 4
LAMP: Yellow
SRT: 00-089		 Low voltage detected at the coolant temperature signal pin 17 of the sensor harness connector. Possible white smoke. Fan will stay on if controlled by the electronic control module (ECM). No engine protection for coolant temperature.

Coolant Temperature Sensor Circuit

Circuit Description

The coolant temperature sensor is used by the ECM to monitor the temperature of the engine coolant. The coolant temperature is used by the ECM for the engine protection system, timing, and fueling control.

Component Location

  • M11 – The coolant temperature sensor is located in the front of the thermostat housing support on most applications. On bus applications, the coolant temperature sensor is usually located at the rear of the thermostat housing support.
  • N14 – The coolant temperature sensor is located on the top of the thermostat housing.

Shop Talk

The resistance of the sensor varies with the temperature. Compare your reading with this table.

Temperature (°C) Temperature [°F] Resistance (ohms)
0 32 30k to 36k
25 77 9k to 11k
50 122 3k to 4k
75 167 1350 to 1500
100 212 600 to 675

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 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 3823256 – female Metri-Pack test lead
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
 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 following test lead when taking a measurement:
Part Number 3823256 – female 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.
 CAUTION 

 

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

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check for multiple fault codes.
STEP 1A. Read the fault codes. Fault Codes 123, 141, 151, 154, 213, 222, 352, and 422 are not active
STEP 2. Check the coolant temperature sensor.
STEP 2A. Inspect the coolant temperature sensor and sensor harness connector pins. No damaged pins
STEP 2B. Read the fault codes. Fault Code 145 active
STEP 2C. Check the resistance of the coolant temperature sensor. 175 ohms to 244k ohms
STEP 2D. Check for a short circuit to ground. More than 100k ohms
STEP 3. Check the sensor harness.
STEP 3A. Inspect the harness and the ECM connector pins. No damaged pins
STEP 3B. Read the fault codes. Fault Code 145 active
STEP 3C. Check for an open circuit. Less than 10 ohms
STEP 3D. Check for a short circuit from pin to pin. More than 100k ohms
STEP 3E. Check for a short circuit to ground. More than 100k ohms
STEP 4. Check for the ECM response.
STEP 4A. Check for the appropriate ECM response. Fault Code 145 inactive, Fault Code 144 active
STEP 5. Clear the fault codes.
STEP 5A. Disable the fault code. Fault Code 145 inactive
STEP 5B. Clear the inactive fault codes. All fault codes cleared

Guided Step 1 – Check for multiple fault codes.

 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, 151, 154, 213, 222, 352, and 422 are not active Possible sensor failure, short circuit to ground in the sensor positive (+) 5 VDC common supply, or short circuit from pin to pin.
Fault Code Multiple A

Guided Step 2 – Check the coolant temperature sensor.

 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 2A – Inspect the coolant temperature sensor and sensor harness connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness from the coolant temperature 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 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 019-201, 019-202, or 019-205.
  • Replace the sensor harness. Refer to Procedure 019-043.
  • Replace the coolant temperature sensor. Refer to Procedure 019-019.
  • Install the appropriate connector seal if it is damaged or missing. Refer to Procedure 019-201, 019-202, or 019-205.

Guided Step 2B – Read the fault codes.

Conditions

  • Connect all components.
  • 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 145 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 lead when taking a measurement:
Part Number 3823256 – female Metri-Pack test lead.
Guided Step 2C – Check the resistance of the coolant temperature sensor.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness from the coolant temperature sensor.

Action

  • Measure the resistance from pin A to pin B of the coolant temperature sensor.
OK NOT OK
175 ohms to 244k ohms Replace the coolant temperature sensor. Refer to Procedure 019-019.

 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 3823256 – female Metri-Pack test lead.
Guided Step 2D – Check for a short circuit to ground.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness from the coolant temperature sensor.

Action

  • Measure the resistance from pin A of the coolant temperature sensor to engine block ground.
OK NOT OK
More than 100k ohms Replace the coolant temperature sensor. Refer to Procedure 019-019.

Guided Step 3 – Check the sensor harness.

 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 a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 3A – Inspect the harness and the 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.

Guided Step 3B – Read the fault codes.

Conditions

  • Connect all components.
  • 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 145 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 lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
Guided Step 3C – Check for an open circuit.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness from the coolant temperature sensor.
  • Disconnect the sensor harness connector from the ECM.

Action

  • Measure the resistance from pin 12 of the sensor harness connector to pin A of the coolant temperature sensor.
  • Measure the resistance from pin 17 of the sensor harness connector to pin B of the coolant temperature sensor.
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 from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness from the coolant temperature sensor.
  • Disconnect the sensor harness connector from the ECM.

Action

  • Measure the resistance from pin 12 of the sensor harness connector to all other pins in the connector.
  • Measure the resistance from pin 17 of the sensor harness connector to all other pins in the connector.
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 to ground.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the sensor harness from the coolant temperature sensor.
  • Disconnect the sensor harness connector from the ECM.

Action

  • Measure the resistance from pin 12 of the sensor harness connector to the engine block ground.
  • Measure the resistance from pin 17 of the sensor harness connector to the engine block ground.
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 for the ECM response.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3822917 – female Deutsch/AMP/Metri-Pack test lead.
Guided Step 4A – Check for the appropriate ECM response.

Conditions

  • Disconnect the sensor harness connector from the ECM.
  • Turn keyswitch ON.

Action

  • Install Part Number 3822917, as a jumper wire, between ECM sensor port pin 12 and pin 17.
  • Read the fault codes using INSITE™.
OK NOT OK
Fault Code 145 inactive, Fault Code 144 active Replace the ECM. Refer to Procedure 019-031.

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 145 is inactive.
OK NOT OK
Fault Code 145 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:  16-Oct-2003
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