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Electronic Control System Gas Plus Engines – FAULT CODE 146 – B and C Gas Plus

Engine Coolant Temperature Sensor Circuit – Temperature Warning

Overview

Engine Coolant Temperature Sensor Circuit – Temperature Warning

CODE REASON EFFECT
Fault Code: 146
PID: P110
SPN: 110
FMI: 0/16
LAMP: Amber
SRT: 

Engine Coolant Temperature Sensor Circuit – Temperature Warning. High coolant temperature warning.

Progressive power derate increasing in severity from time of alert.

Engine Coolant Temperature Sensor Circuit (B Gas Plus, B LPG Plus and C Gas Plus)
SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) uses the coolant temperature sensor for engine protection purposes.

Component Location

The coolant temperature sensor is located near the water outlet connection.

Shop Talk

All temperature sensors:

  • The resistance of the sensor varies with temperature. The reading you observe should compare to the following table if the sensor is functioning properly.
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 damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Read the fault codes. Fault Code 146 active?
STEP 2. Check the sensor accuracy.  
  STEP 2A. Verify the sensor accuracy with a thermocouple or similar temperature probe. Does the temperature differ more than 3°C or 5°F?
STEP 3. Check the Coolant Temperature Sensor.  
  STEP 3A. Inspect the Coolant Temperature Sensor and Engine Harness connector pins. Dirty or damaged pins?
  STEP 3B. Read the fault codes. Fault Code 146 active?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 146 inactive?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Read the fault codes.

Conditions

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

Action

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

Fault Code 146 active?
YES NO
No Repair No Repair

Guided Step 2 – Check the sensor accuracy.

 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 – Verify the sensor accuracy with a thermocouple or similar temperature probe.

Conditions

  • Connect a temperature gauge to the engine
  • Connect INSITE™ electronic service tool to the vehicle data link
  • Turn keyswitch ON.

Action

  • Compare the coolant temperature reading on INSITE™ electronic service tool, to the reading from the temperature probe.

Note: If no temperature measuring device is available, answer “NO” to this step.

Does the temperature differ more than 3°C or 5°F?
YES NO

Replace the coolant sensor. Refer to Procedure 019-157.

 No Repair

Guided Step 3 – Check the Coolant Temperature Sensor.

Guided Step 3A – Inspect the Coolant Temperature Sensor and Engine Harness connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the Engine Harness from the Coolant Temperature Sensor.

Action

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

Dirty or damaged pins?
YES NO

Repair or replace the Engine Harness, or replace the sensor, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing
  • Repair the Engine Harness. Refer to Procedure 019–202.
  • Replace the Engine Harness. Refer to Procedure 019–043.
  • Replace the Coolant Temperature Sensor. Refer to Procedure 019–157.
 No Repair

Guided Step 3B – Read the fault codes.

Conditions

  • Connect all components
  • Turn the keyswitch ON.

Action

  • Start the engine and let it run for one minute.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 146 active?
YES NO

Refer to the Coolant Temperature Above Normal troubleshooting symptom chart in Section TS of the Troubleshooting and Repair Manual C Gas, C Gas Plus, and L Gas Plus Engines, Bulletin 3666206, and in the Troubleshooting and Repair Manual B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin 3666164.

 No Repair

Guided Step 4 – Clear the fault codes.

Guided Step 4A – Disable the fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

  • Start the engine and let it idle for one minute.
  • Verify that Fault Code 146 is inactive.

Fault Code 146 inactive?
YES NO
No Repair

Troubleshooting procedures need to be repeated from the beginning.

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON.

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:  28-Sep-2004
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