Posted on by

Electronic Control System Gas Plus Engines – FAULT CODE 235 B and C Gas Plus

Engine Coolant Level Low – Critical

View Related Topic

Overview

Engine Coolant Level Low – Critical

CODE REASON EFFECT
Fault Code: 235
PID: P111
SPN: 111
FMI: 1
LAMP: Red
SRT: 

Coolant level low – data valid but below normal operating range – most severe level. Low engine coolant level detected.

Progressive power and speed derate; if engine protection shutdown is enabled, engine will shut down after 30 seconds of the lamp flashing.

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

Circuit Description

There are two coolant signal level wires, one for high coolant level and one for low coolant level. The sensor is OEM-supplied.

Component Location

The coolant level sensor is usually located in the coolant supply tank. Refer to the OEM manual for the component location.

Shop Talk

The engine protection for coolant level is a customer feature and will
only be enabled at the customer’s request. This sensor
must deactivate or disable the fuel control valve if this feature is utilized by the OEM.

A coolant level sensor or shorting plug is required on all Gas Plus engines.

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.
 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 the fault codes.  
  STEP 1A. Read the fault codes. Fault Code 235 active?
STEP 2. Check the coolant level.  
  STEP 2A. Verify the coolant level. Coolant level normal?
STEP 3. Check the coolant level sensor and harness.  
  STEP 3A. Inspect the engine harness and coolant level sensor connector pins. No damaged pins?
  STEP 3B. Read the fault codes. Fault Code 235 active?
STEP 4. Check the ECM and harness.  
  STEP 4A. Inspect the engine harness and ECM connector pins Dirty or damaged pins?
  STEP 4B. Read the fault codes. Fault Code 235 active?
  STEP 4C. Check for an open circuit. Less than 10 ohms?
  STEP 4D. Check for a short circuit from pin to pin. More than 100k ohms?
STEP 5. Verify the coolant level.  
  STEP 5A. Verify the coolant level with INSITE™ electronic service tool. INSITE™ electronic service tool reading of coolant level correct?
  STEP 5B. Check the sensor supply voltage. 4.5 to 5.5 VDC?
STEP 6. Clear the fault codes.  
  STEP 6A. Disable the fault code. Fault Code 235 inactive?
  STEP 6B. 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

Read the fault codes.

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

Fault Code 235 active?
YES NO
No Repair No Repair

Guided Step 2 – Check the coolant level.

Guided Step 2A – Verify the coolant level.

Conditions

  • Turn keyswitch OFF.

Action

Check the coolant level.

  • Remove the radiator cap or top tank reservoir and inspect the coolant level.

Coolant level normal?
YES NO
No Repair

Add coolant to the system.
Refer to the Cummins® Coolant Requirements and Maintenance, Bulletin 3666132.

Check for coolant leaks. Refer to Symptom Tree Coolant Loss T019 in the C8.3G, C Gas Plus, and L Gas Plus Troubleshooting and Repair Manual, Bulletin 3666206 or
the B5.9G, 5.9LPG, B Gas Plus, B LPG Plus, B Gas International, and G5.9 Troubleshooting and Repair Manual, Bulletin 3666164.

Guided Step 3 – Check the coolant level sensor and harness.

Guided Step 3A – Inspect the engine harness and coolant level sensor connector pins.

Conditions

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

Action

Inspect the engine harness and coolant level sensor connector pins for the following:

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

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

For general inspection techniques, refer to Procedure 019-361 (Component Connector and Pin Inspection) in Section 19.

Dirty or damaged pins?
YES NO

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

 No Repair

Guided Step 3B – Read the fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

Read the fault codes.

  • Start the engine and let it idle for 1 minute.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 235 active?
YES NO
No Repair No Repair

Guided Step 4 – Check the ECM and Harness.

Guided Step 4A – Inspect the engine harness and ECM connector pins.

Conditions

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

Action

Inspect the engine harness and ECM connector pins for the following:

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

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

For general inspection techniques, refer to Procedure 019-361 (Component Connector and Pin Inspection) in Section 19.

Dirty or damaged pins?
YES NO

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

 No Repair

Guided Step 4B – Read the fault codes.

Conditions

  • Connect all components
  • Turn the keyswitch ON.

Action

Read the fault codes.

  • Start the engine and let it idle for 1 minute.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 235 active?
YES NO
No Repair No Repair

Guided Step 4C – Check for an open circuit.

Conditions

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

Action

Check for an open circuit.

  • Measure the resistance from the coolant level SIGNAL pins in the engine harness ECM connector 1 to the SIGNAL pins in the OEM harness sensor connector.
  • Measure the resistance from the coolant level RETURN pin in the engine harness ECM connector 2 to the coolant level RETURN pin in the OEM harness sensor connector.

Less than 10 ohms?
YES NO
No Repair

Repair or replace the engine harness or OEM harness.

Guided Step 4D – Check for a short circuit from pin to pin.

Conditions

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

Action

Check for a short circuit from pin to pin.

  • Measure the resistance from the coolant level SIGNAL pins in the engine harness ECM connector 1 to all other pins in the connector.
  • Measure the resistance from the coolant level SIGNAL pins in the engine harness ECM connector 1 to all other pins in the engine harness connector 2.
  • Measure the resistance from the coolant level RETURN pin in the engine harness ECM connector 2 to all other pins in the connector.
  • Measure the resistance from the coolant level RETURN pins in the engine harness ECM connector 2 to all other pins in the engine harness connector 1.
SMALL | MEDIUM | LARGE

More than 100k ohms?
YES NO
No Repair

Repair or replace the engine harness or OEM harness.

Guided Step 5 –

Guided Step 5A – Verify the coolant level with INSITE™ electronic service tool.

Conditions

  • Turn keyswitch OFF
  • Install the shorting plug into the coolant level sensor connector
  • Turn keyswitch ON.

Action

Use INSITE™ electronic service tool to verify the coolant level.

Verify the Engine Coolant Level Sensor high reading is “ON” with INSITE™ electronic service tool and the Engine Coolant Level Sensor low reading is “OFF”.

INSITE™ electronic service tool reading of coolant level correct?
YES NO
No Repair

Replace the sensor. Refer to the OEM service manual.

Guided Step 5B – Check the sensor supply voltage.

Conditions

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

Action

Check the sensor supply voltage.

  • Measure the voltage from the coolant level SUPPLY pin in the sensor connector to engine block ground.

4.5 to 5.5- VDC?
YES NO
  • Repair or replace the coolant level sensor. Refer to the OEM service manual.

Guided Step 6 – Clear the fault codes.

Guided Step 6A – Disable the fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

Disable the fault code.

  • Start the engine and let it idle for 1 minute.
  • Verify that Fault Code 235 is inactive.

Fault Code 235 inactive?
YES NO
No Repair

Troubleshooting procedures need to be completed again from the beginning.

Guided Step 6B – Clear the inactive fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

Clear the inactive fault codes.

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

All fault codes cleared?
YES NO
No Repair

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting charts
Last Modified:  19-Dec-2007
Avatar photo

Published by Jack

Hello, I'm Jack, a diesel engine fan and a blogger. I write about how to fix and improve diesel engines, from cars to trucks to generators. I also review the newest models and innovations in the diesel market. If you are interested in learning more about diesel engines, check out my blog and leave your feedback.