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Electronic Control System Gas Plus Engines – FAULT CODE 231

Engine Coolant Pressure Sensor Circuit – Shorted High

Overview

CODE REASON EFFECT
Fault Code: 231
PID: P109
SPN: 109
FMI: 3
LAMP: Amber
SRT: 

Engine Coolant Pressure Sensor Circuit – Shorted High

None on performance. No engine protection for coolant pressure.

Engine Coolant Pressure Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The engine coolant pressure/temperature sensor is used by the electronic control module (ECM) to monitor the coolant pressure. The ECM monitors the voltage on the signal pin and converts this to a pressure value. The coolant pressure value is used by the ECM for the engine protection system.

Component Location

The coolant pressure/temperature sensor is located in the block, below the water outlet location.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Check for 227 fault codes. Fault Code 227 active?
  STEP 1B. Check for an inactive fault code. Fault Code 231 inactive?
STEP 2. Check the coolant pressure sensor and circuit.  
  STEP 2A. Inspect the coolant pressure sensor and connector pins. Dirty or damaged pins?
  STEP 2B. Check the circuit response. Fault Code 232 active and Fault Code 231 inactive?
  STEP 2C. Check the sensor supply voltage and return circuit. 4.5 to 5.25 VDC?
  STEP 2D. Check the fault codes and verify sensor condition. Fault Code 231 active?
STEP 3. Check the ECM and engine harness.  
  STEP 3A. Inspect ECM and engine harness connector pins. Dirty or damaged pins?
  STEP 3B. Check for an open circuit in the engine harness. Less than 10 ohms?
  STEP 3C. Check for a pin to pin short circuit in the engine harness. Greater than 100k ohms?
  STEP 3D. Check for a pin to pin short circuit in the engine harness. Greater than 100k ohms?
  STEP 3E. Check for an inactive fault code. Fault Code 231 inactive?
STEP 4. Clear the fault code.  
  STEP 4A. Disable the fault code. Fault Code 231 inactive?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Check for 227 fault codes.

Conditions

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

Action

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

Fault Code 227 active?
YES NO
No Repair No Repair
Fault Code 227

Guided Step 1B – Check for an inactive fault code.

Conditions

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

Action

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

Fault Code 231 inactive?
YES NO
No Repair No Repair

Guided Step 2 – Check the coolant pressure sensor and circuit.

Guided Step 2A – Inspect the coolant pressure sensor and connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the coolant pressure sensor from the engine harness.

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Wire insulation damaged
  • 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 Pin Inspection, Procedure 019-361.

Dirty or damaged pins?
YES NO

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

Repair the damaged pins.

Repair or replace the engine harness, or replace the sensor, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins 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 sensor. Refer to Procedure 019-188.
 No Repair

Guided Step 2B – Check the circuit response.

Conditions

  • Turn keyswitch OFF
  • Disconnect the coolant pressure sensor from the engine harness
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

Check for the appropriate circuit response after 30 seconds.

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

Fault Code 232 active and Fault Code 231 inactive?
YES NO
No Repair No Repair

Guided Step 2C – Check the sensor supply voltage and return circuit.

Conditions

  • Turn keyswitch OFF
  • Disconnect the coolant pressure sensor from the engine harness
  • Turn keyswitch ON.

Action

  • Measure the voltage between the 5 Volt SUPPLY pin and the coolant pressure RETURN pin at the coolant pressure sensor connector of the engine 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 2D – Check the fault codes and verify sensor condition.

Conditions

  • Turn keyswitch OFF
  • Connect the coolant pressure sensor to the engine harness
  • Turn keyswitch ON
  • Connect INSITE™ electronic service tool.

Action

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

Fault Code 231 active?
YES NO

A defective sensor has been detected,

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

 No Repair

Guided Step 3 – Check the ECM and engine harness.

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

Conditions

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

Action

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

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

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 connector or engine harness connector.

Repair the damaged pins.

Repair or replace the engine harness, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins 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 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.
No Repair

Guided Step 3B – Check for an open circuit in the engine harness.

Conditions

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

Action

  • Measure the resistance between the engine harness ECM connector 2 RETURN pin and the coolant pressure sensor connector RETURN pin.

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

For general inspection techniques, refer to Component Connector and Pin Inspection, Procedure 019-360.

Less than 10 ohms?
YES NO
No Repair

An open RETURN circuit has been detected in the engine harness

Repair or replace the engine harness, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins 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.

Guided Step 3C – Check for a pin to pin short circuit in the engine harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 1 and connector 2 from the ECM
  • Disconnect the coolant pressure sensor from the harness.

Action

  • Measure the resistance between the coolant pressure SIGNAL pin in the engine harness connector 1 and all other pins in the engine connector 1.
  • Measure the resistance between the coolant pressure SIGNAL pin in the engine harness connector 1 and all other pins in the engine connector 2.

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

For general inspection techniques, refer to Component Connector and Pin Inspection, Procedure 019-360.
SMALL | MEDIUM | LARGE

Greater than 100k ohms?
YES NO
No Repair

An pin to pin short circuit on the SIGNAL line has been detected in the engine harness

Repair or replace the engine harness, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins 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 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3D – Check for a pin to pin short circuit in the engine harness.

Conditions

  • Turn keyswitch OFF
  • Disconnect the engine harness connector 1 and connector 2 from the ECM
  • Disconnect the coolant pressure sensor from the harness.

Action

  • Measure the resistance between the coolant pressure 5 Volt SUPPLY pin in the engine harness connector 2 and all other pins in the engine connector 2.
  • Measure the resistance between the coolant pressure 5 Volt SUPPLY pin in the engine harness connector 2 and all other pins in the engine connector 1.

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

For general inspection techniques, refer to Component Connector and Pin Inspection, Procedure 019-360.
SMALL | MEDIUM | LARGE

Greater than 100k ohms?
YES NO
No Repair

An pin to pin short circuit on the SUPPLY line has been detected in the engine harness

Repair or replace the engine harness, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins 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 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.

Guided Step 3E – 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 231 inactive?
YES NO
No Repair

Replace the ECM. Call for pre-authorization.

Refer to Procedure 019-031.

Guided Step 4 – Clear the fault code.

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 231 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 steps
Last Modified:  03-Sep-2004
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Published by Jack

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