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Engine Coolant Level – Engine Protection
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Overview
| CODE | REASON | EFFECT |
| Fault Code: 235 PID: P111 SPN: 111 FMI: 1 LAMP: Engine Protection, Red, or Yellow* SRT: 00-107 |
Voltage on the coolant level low signal pin 9 of the coolant level sensor on the sensor harness connector indicates low radiator coolant level. | Progressive power and speed derate with increasing time after alert. If Engine Protection Shutdown is enabled, engine will shut down 30 seconds after the engine protection lamp or the Red lamp* starts flashing. |
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Engine Coolant Level – Engine Protection |
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Circuit Description
The coolant level sensor checks the coolant level in the coolant system and informs the electronic control module (ECM) through the sensor harness. The coolant level sensor is complex; do not use a multimeter to test it. If the radiator coolant drops below a certain level, a progressive power and speed derate with increasing time after the alert will occur.
Component Location
The coolant level sensor is located in the radiator top tank or surge tank.
Shop Talk
This is an OEM-supplied component and can vary in sensor location.
- When coolant level drops, a power derate occurs, decreasing output by 50 percent over a 30-second period.
- If a shorting plug is used in the coolant level circuit, verify that it is wired correctly.
- Inspect the wiring harness between the 9-pin Deutsch connector and the coolant level sensor for damage.
- Verify the radiator surge tank is metal. The coolant level sensor will not work with a nonconductive tank material.
- The coolant level sensor location must be in the middle of the tank rather than off to one side where the coolant level can change when the vehicle turns a corner.
- The CELECT™ Troubleshooting and Repair Manual shows a Robert Shaw coolant level sensor. Not all vendors label their coolant level sensor this way; refer to the vendor to verify the sensor pin is wired to the correct ECM pin.
*Applies to 98N14 and 98M11 calibrations only.
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.
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 CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
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CAUTION
To reduce the possibility of damaging the new ECM, all other active fault codes must be investigated prior to replacing the ECM. |
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CAUTION
Do not add cold coolant to a hot engine. Castings can be damaged. Allow engine to cool to below 50°C [120°F] before adding coolant. |
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CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
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CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
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CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
Troubleshooting Steps
| STEPS | SPECIFICATIONS | |
|---|---|---|
| STEP 1. | Verify the coolant is low. | |
| STEP 1A. Check the coolant level. | Coolant level is normal | |
| STEP 2. | Check the coolant level sensor. | |
| STEP 2A. Confirm the fault is still active with the engine running. | Fault Code 235 active | |
| STEP 3. | Check the sensor harness. | |
| STEP 3A. Check for an open circuit. | Less than 10 ohms | |
| STEP 3B. Check for a short circuit to ground. | More than 100k ohms | |
| STEP 3C. Check for a short circuit from pin to pin in the sensor harness. | More than 100k ohms | |
| STEP 3D. Check for a short from pin to pin in the actuator harness. | More than 100k ohms | |
| STEP 4. | Check the ECM. | |
| STEP 4A. Check the ECM response. | Fault Code 235 inactive | |
| STEP 5. | Clear the fault codes. | |
| STEP 5A. Disable the fault code. | Fault Code 235 inactive | |
| STEP 5B. Clear the inactive fault codes. | All fault codes cleared | |
Guided Step 1 – Verify the coolant is low.
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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.
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CAUTION
Do not add cold coolant to a hot engine. Castings can be damaged. Allow engine to cool to below 50°C [120°F] before adding coolant. |
| Guided Step 1A – Check the coolant level. | |
|---|---|
Conditions
Action
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| OK | NOT OK |
| Coolant level is normal | Add coolant to the radiator.
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Guided Step 2 – Check the coolant level sensor.
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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.
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| Guided Step 2A – Confirm the fault is still active with the engine running. | |
|---|---|
Conditions
Action
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| OK | NOT OK |
| Fault Code 235 active | Fault Code 235 inactive |
Guided Step 3 – Check the sensor harness.
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CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
| Guided Step 3A – Check for an open circuit. | ||
|---|---|---|
Conditions
Action
Note: Check OEM harness from 9-pin OEM connector to the coolant level sensor for proper pin-to-pin wiring and continuity. Pin-to-pin wiring on OEM side of connector varies by OEM. See OEM wiring diagram for specific coolant level sensor wiring. Check for proper pin-to-pin wiring, continuity from pin to pin, and pin to ground shorts in shorting plug if there is no coolant level sensor. Shorting plug must be wired such that the 9-pin connector is wired A to C and B to J. |
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| OK | NOT OK | |
| Less than 10 ohms | Repair or replace the sensor harness. | |
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CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
| Guided Step 3B – Check for a short circuit to ground. | ||
|---|---|---|
Conditions
Action
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| OK | NOT OK | |
| More than 100k ohms | Repair or replace the sensor harness. | |
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CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
| Guided Step 3C – Check for a short circuit from pin to pin in the sensor harness. | ||
|---|---|---|
Conditions
Action
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| OK | NOT OK | |
| More than 100k ohms | Repair or replace the sensor harness. | |
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CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
| Guided Step 3D – Check for a short circuit from pin to pin in the actuator harness. | |
|---|---|
Conditions
Action
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| OK | NOT OK |
| More than 100k ohms | Repair or replace the sensor harness. |
Guided Step 4 – Check the ECM.
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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.
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CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement: |
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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 4A – Check the ECM response. | ||
|---|---|---|
Conditions
Action
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| OK | NOT OK | |
Fault Code 235 inactive
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Replace the ECM. Refer to Procedure 019-031. | |
Guided Step 5 – Clear the fault codes.
| Guided Step 5A – Disable the fault code. | |
|---|---|
Conditions
Action
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| OK | NOT OK |
| Fault Code 235 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
Action
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| OK | NOT OK |
| All fault codes cleared | Troubleshoot any remaining active fault codes. |
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Repair complete
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Appropriate troubleshooting chart
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