System Operation Description:
The coolant level sensor is an OEM installed component for the vehicle. This sensor is the only optional sensor for “Engine Monitoring”. “Engine Monitoring” is a programmable feature of the Caterpillar ECM. The sensor is selectable through a customer programmable parameter and the customer programmable parameter may be protected by customer passwords. Some OEM installed coolant level sensors are not connected to the Engine Control Module (ECM). Do not confuse an OEM installed “Coolant Level Sensor” that is independent of “Engine Monitoring” with the “Coolant Level Sensor” that is used for “Engine Monitoring”.
The sensor operates as a coolant level sensor. The sensor indicates the presence or the absence of coolant at the sensor probe. There are two options if a coolant level sensor is installed.
• “4-pin”
• “2-wire Float Sensor”
If a coolant level sensor is not installed or the coolant level sensor is independent from the ECM, the parameter should be programmed to “None”.
“4-pin”
The sensor is powered from the ECM through the ECM connector J1/P1:2 (+5 VDC). The signal wires for the coolant level sensor are connected to pins J1/P1:54 (Coolant Level Low) and to J1/P1:49 (Coolant Level Normal) on the ECM. The sensor common is connected to the ECM connector J1/P1:5 (AP Sensor/Switch Sensor Common).
If coolant is present at the sensor probe, “Coolant Level Low” has an output of near 0 VDC. If coolant is present at the sensor probe, “Coolant Level Normal” has an output near +5 VDC. If coolant is not present at the sensor probe, the “Coolant Level Low” output would be near +5 VDC. If coolant is not present at the sensor probe, the “Coolant Level Normal” output would be near 0 VDC.
“2-wire Float Sensor”
The sensor is powered with +5 VDC from the ECM through ECM connector J1/P1:26. The sensor is also connected to J1/P1:5 (AP Sensor/Switch Sensor Common).
Resistance through the sensor is varied by the coolant level. The voltage at the normal operating range is between 0.75 VDC and 1.75 VDC.
Note: The “Coolant Level Sensor” is set when the coolant level sensor is programmed to “4-Pin” or “2-wire Float Sensor”. If this parameter is set and a sensor is not installed, the following diagnostic code will be logged:
• 111-02 Coolant Level signal invalid
The “Engine Monitoring Lamps” parameter is used in order to determine if a single warning lamp is used for the engine monitoring system or if discrete lamps are used for each monitored condition. If the “Engine Monitoring Lamps” parameter is programmed to “Warning Lamp”, a single lamp is connected to J1/P1:29. If the “Engine Monitoring Lamps” parameter is programmed to “Option 1” and a coolant level sensor is installed, then a discrete lamp for low coolant level is connected to J1/P1:30. The “Coolant Level Sensor” parameter must be programmed for the lamp to operate correctly.
Test Step 1. Check for an Active Coolant Level Sensor Fault
A. Connect the Caterpillar Electronic Technician (Cat ET) to the data link connector.
B. Turn the key switch to the ON position.
C. Check for active diagnostic codes on Cat ET.
Expected Result:
One of the following diagnostic codes is active.
• 111-02 Coolant Level signal invalid
• 111-03 Coolant Level voltage high
• 111-04 Coolant Level voltage low
Results:
• OK – Proceed to Test Step 2.
• Not OK – 111-01, 111-11, or 111-14 is active.
Repair: Refer to Troubleshooting, “Troubleshooting with a Diagnostic Code” for the proper troubleshooting procedure.
STOP.
• No Codes – If none of the specified diagnostic codes are present, clear all diagnostic codes. If a problem is still suspected with the coolant level sensor, proceed to Test Step 2.
Test Step 2. Determine the type of Coolant Level Sensor
A. Check the coolant level sensor in order to determine the type of sensor that is installed on the vehicle.
Expected Result:
A “4-pin” or “2-wire Float Sensor” is installed.
Results:
• “4-pin” – Proceed to Test Step 3.
• “2-wire Float” – Proceed to Test Step 9.
• None
Repair: If a coolant level sensor is not installed, change the “Coolant Level Sensor” parameter to “None”.
Verify that the repair eliminates the problem.
STOP.
Test Step 3. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the J1/P1 ECM connector, the connector for the coolant level sensor and the terminals in the connectors. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.
B. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the following connections:
• J1/P1:2
• J1/P1:5
• J1/P1:49
• J1/P1:54
Refer to Illustration 57.
C. Check the ECM connector (Allen Head Screw) for the proper torque of 6.0 N·m (55 lb in).
D. Check the harness and wiring for abrasion and pinch points from the sensor to the ECM.
Expected Result:
All connectors, pins and sockets should be completely coupled and/or inserted and the harness and wiring should be free of corrosion, abrasion or pinch points.
Results:
• OK – Proceed to Test Step 4.
• Not OK
Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.
Verify that the repair eliminates the problem. Clear all diagnostic codes.
STOP.
Test Step 4. Check the Supply Voltage at the Sensor
A. Turn the key switch to the OFF position.
B. Disconnect the coolant level sensor from the harness.
C. Turn the key switch to the ON position.
D. Measure the voltage at the harness connector between Terminal C (+5 V Sensor Supply) and Terminal B (AP Sensor/Switch Sensor Common).
Expected Result:
The measured voltage is between 4.5 VDC and 5.5 VDC.
Results:
• OK – The voltage is within the proper range.
Proceed to Test Step 6.
• Not OK – There is a problem with the sensor supply. Proceed to Test Step 5.
Test Step 5. Check the Supply Voltage at the ECM
A. Turn the key switch to the OFF position.
B. Disconnect the J1/P1 ECM connector.
C. Install a 140-2266 Cable (Seventy-Pin Breakout) between ECM connector J1 and ECM connector P1.
Note: The P1 ECM connector must be connected to the breakout T in order for the ECM to receive battery voltage.
D. Turn the key switch to the ON position.
E. Measure the voltage between Terminal 2 (+5 V Sensor Supply) and Terminal 5 (AP Sensor/Switch Sensor Common) at the breakout T.
Expected Result:
The measured voltage is between 4.5 VDC and 5.5 VDC.
Results:
• OK – The problem is located in the harness wiring.
Repair: Remove the breakout T. Reconnect the J1/P1 ECM connectors.
Measure the voltage between Terminal C and chassis ground at the connector for the coolant level sensor on the vehicle harness.
If the voltage is between 4.5 VDC and 5.5 VDC, the problem is with the common wire. If the voltage is not within the proper range, the problem is with the supply wire.
Repair the wiring or replace the wiring, as required.
Verify that the repair eliminates the problem.
STOP.
• Not OK – There may be a problem with the ECM.
Repair: Temporarily connect a test ECM. Ensure that the “Engine Monitoring” and the “Coolant Level Sensor” are programmed to match the old ECM.
Check the test ECM by measuring the voltage between Terminal 2 and Terminal 5 at the breakout T.
If the test ECM fixes the problem, reconnect the suspect ECM.
If the problem returns with the suspect ECM, permanently replace the ECM.
Verify that the repair eliminates the problem.
STOP.
Test Step 6. Check the Circuit for the Coolant Level Sensor
A. Turn the key switch to the OFF position.
B. Insert a jumper wire between Terminal D (Coolant Level Normal) and Terminal B (AP Sensor/Switch Sensor Common) at the harness connector.
C. Turn the key switch to the ON position.
D. While the jumper wire is in place, access the status for “Coolant Level” on Cat ET.
E. Check for active diagnostic codes.
F. Turn the key switch to the OFF position.
Expected Result:
The status for “Coolant Level” indicates “LOW” while the jumper wire is in place. A 111-01 Low Coolant Level Warning is active while the jumper wire is in place.
Results:
• OK – The ECM responded correctly. Proceed to Test Step 7.
• Not OK – Proceed to Test Step 8.
Test Step 7. Check the Circuit for the Coolant Level Low
A. Turn the key switch to the OFF position.
B. Insert a jumper wire between Terminal A (Coolant Level Low) and Terminal B (AP Sensor/Switch Sensor Common) at the harness connector.
C. Turn the key switch to the ON position.
D. Check for active diagnostic codes on Cat ET.
E. Check the status for “Coolant Level” on Cat ET.
Expected Result:
There are no active diagnostic codes while the jumper wire is in place. The status for “Coolant Level” displays “OK”.
Results:
• OK – The harness and the ECM are working correctly.
Repair: Remove the jumper wire.
Replace the sensor and reconnect the harness to the sensor.
Verify that the repair eliminates the problem.
STOP.
• Not OK – Proceed to Test Step 8.
Test Step 8. Check the ECM for Proper Operation
A. Disconnect the J1/P1 ECM connector.
B. Install a breakout T between the J1 and P1 ECM connectors.
C. Fabricate two jumper wires 100 mm (4 inch) long.
Crimp a Deutsch pin to both ends of each wire.
D. Turn the key switch to the ON position.
E. Monitor the status for “Coolant Level” on Cat ET. Insert a jumper wire between Terminal 49 (Coolant Level Normal) and Terminal 5 (AP Sensor/Switch Sensor Common) of the breakout T.
F. Monitor the status for “Coolant Level” while the jumper is being inserted and removed. Wait
for 30 seconds between the insertion of the jumper and the removal of the jumper. The status for “Coolant Level” will display “Low” while the jumper wire is in place. Also, the following diagnostic code should be active:
• 111-01 Low Coolant Level Warning
Note: 111-14 Low Coolant Level Warning will be active during the first six hours of engine operation.
G. Record the result.
H. Monitor the status for “Coolant Level” on Cat ET. Insert a jumper wire between Terminal 54 (Coolant Level Low) and Terminal 5 (AP Sensor/Switch Sensor Common) of the breakout T.
I. Monitor the status for “Coolant Level” while the jumper is being inserted and removed. Wait
for 30 seconds between the insertion of the jumper and the removal of the jumper. The status for “Coolant Level” will display “OK” while the jumper wire is in place. Also, there should be no active diagnostic codes.
Expected Result:
The “Coolant Level” status behaves in the following manner:
• The status for “Coolant Level” indicates “Low” when the jumper wire is installed between Terminal 49 and Terminal 5. Also, 111-01 Low Coolant Level Warning is active.
Note: 111-14 Low Coolant Level Warning will be active during the first six hours of engine operation.
• The status for “Coolant Level” indicates “OK” when the jumper wire is installed between
Terminal 54 and Terminal 5. Also, there are no active diagnostic codes.
Results:
• OK – The ECM is functioning properly.
Repair: Repair the harness or replace the harness, as required.
Verify that the repair eliminates the problem. Clear all diagnostic codes.
STOP.
• Not OK
Repair: Temporarily connect a test ECM. Ensure that the “Engine Monitoring” and the “Coolant Level Sensor” are programmed to match the old ECM.
Repeat this Test Step with the test ECM.
If the test ECM fixes the problem, reconnect the suspect ECM.
If the problem returns with the suspect ECM, permanently replace the ECM.
Verify that the repair eliminates the problem.
STOP.
Test Step 9. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the J1/P1 ECM connector, the connector for the coolant level sensor and the terminals for the coolant level sensor in the connectors. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.
B. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the following connections:
• P1/J1:26 (Coolant level input)
• P1/J1:5 (AP sensor/switch sensor common) Refer to Illustration 60.
C. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).
D. Check the harness and wiring for abrasion and pinch points from the sensor to the ECM.
Expected Result:
All connectors, pins and sockets should be completely coupled and/or inserted and the harness and wiring should be free of corrosion, abrasion or pinch points.
Results:
• OK – Proceed to Test Step 10.
• Not OK
Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.
Verify that the repair eliminates the problem. Clear all diagnostic codes.
STOP.
Test Step 10. Verify that the Diagnostic Code is Still Active
A. Turn the key switch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
B. Check for active diagnostic codes on Cat ET.
Expected Result:
One of the following diagnostic codes is active.
• 111-02 Coolant Level signal invalid
• 111-03 Coolant Level voltage high
• 111-04 Coolant Level voltage low
Results:
• 111-02 – A fault for the coolant level sensor is active. Proceed to Test Step 11.
• 111-03 – A “voltage high” diagnostic code (open circuit) is active at this time. Proceed to Test Step 15.
• 111-04 – A “voltage low” diagnostic code (short circuit) is active at this time. Proceed to Test Step 13.
Test Step 11. Disconnect the Coolant Level Sensor and Check the Supply Voltage (+5 VDC)
A. Turn the key switch to the OFF position.
B. Disconnect the coolant level sensor from the harness.
C. Use a multimeter to measure the voltage at the harness connector.
D. Turn the key switch to the ON position.
Expected Result:
The measured voltage is between 4.5 VDC and 5.5 VDC.
Results:
• OK – The correct voltage is reaching the sensor.
Repair: Replace the sensor.
STOP.
• Not OK – Proceed to Test Step 12.
Test Step 12. Disconnect the Terminal for the Sensor Supply (+5 VDC) from the ECM Connector
A. Turn the key switch to the OFF position.
B. Disconnect the J1/P1 ECM connector.
C. Install a breakout T between ECM connector J1 and ECM connector P1.
D. Turn the key switch to the ON position.
E. Measure the voltage at the breakout T from terminal 26 to terminal 5.
Refer to Illustration 61.
Expected Result:
The measured voltage is between 4.5 VDC and 5.5 VDC.
Results:
• OK – The problem is located in the harness wiring.
Repair: Repair the wiring or replace the wiring, as required.
Verify that the repair eliminates the problem.
STOP.
• Not OK – The problem is on the ECM side.
Repair: Temporarily connect a test ECM. Ensure that the “Engine Monitoring” and the “Coolant Level Sensor” are programmed to match the old ECM. Check the test ECM by measuring the voltage at the breakout T from terminal 26 to terminal 5 again. If the problem is resolved with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.
STOP.
Test Step 13. Disconnect the Sensor in order to Create an Open Circuit
A. Turn the key switch to the OFF position.
B. Disconnect the coolant level sensor at the sensor in order to create an open circuit.
C. Turn the key switch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
D. Check for active diagnostic codes on Cat ET.
Expected Result:
111-03 Coolant Level voltage high is now active.
Results:
• OK – There is a “voltage high” diagnostic code (open circuit) when the connector is disconnected.
Repair: There is a short in the coolant level sensor.
1. Repair the sensor or replace the sensor.
2. Verify that the repair eliminates the problem.
STOP.
• Not OK – There is still a “voltage low” diagnostic code (short circuit). Proceed to Test Step 14.
Test Step 14. Create an Open Circuit at the ECM
A. Turn the key switch to the OFF position.
B. Remove the wires from P1:26 and J1:5 in order to create an open circuit at the ECM.
C. Turn the key switch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
D. Check for active diagnostic codes on Cat ET.
Expected Result:
111-03 Coolant Level voltage high is now active.
Results:
• OK – There is a short circuit in the harness between the ECM and the coolant level sensor.
Proceed to Test Step 17.
• Not OK – The “voltage low” diagnostic code (short circuit) is still present.
Repair: Perform the following procedure:
1. Temporarily connect a test ECM. Refer to Troubleshooting, “Programming Parameters” before replacing the ECM.
2. If the test ECM fixes the problem, reconnect the suspect ECM. If the problem returns, permanently install the new ECM.
STOP.
Test Step 15. Create a Short Circuit at the Sensor
A. Turn the key switch to the OFF position.
B. Disconnect the coolant level sensor at the sensor.
C. Fabricate a jumper wire between terminal 1 and terminal 2 of the connector for the coolant level sensor in order to create a short circuit.
D. Turn the key switch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
E. Check for active diagnostic codes on Cat ET.
Expected Result:
111-04 Coolant Level voltage low is now active.
Results:
• OK – There is an open circuit in the coolant level sensor.
Repair: Perform the following procedure:
1. Repair the coolant level sensor or replace the coolant level sensor.
2. Verify that the repair eliminates the problem.
STOP.
• Not OK – The “voltage high” diagnostic code (open circuit) is still active. Proceed to Test Step 16.
Test Step 16. Create a Short Circuit at the ECM
A. Turn the key switch to the OFF position.
B. Remove the wires from P1:26 and P1:5.
C. Fabricate a jumper wire between P1:26 and P1:5 in order to create a short circuit.
D. Turn the key switch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
E. Check for active diagnostic codes on Cat ET.
Expected Result:
111-04 Coolant Level voltage low is now active.
Results:
• OK – There is a problem in the harness between the ECM and the solenoid. Proceed to Test Step 17.
• Not OK – There is still a “voltage high” diagnostic code (open circuit).
Repair: Perform the following procedure:
1. Temporarily connect a test ECM. Refer to Troubleshooting, “Programming Parameters” before replacing the ECM.
2. If the test ECM fixes the problem, reconnect the suspect ECM. If the problem returns, permanently install the new ECM.
STOP.
Test Step 17. Bypass the Harness Wiring between the ECM and the Solenoid
A. Turn the key switch to the OFF position.
B. Remove the wires from P1:26 and P1:5. Also remove the wires from the connector for the coolant level sensor.
C. Fabricate two jumper wires to reach from the ECM to the connector for the coolant level sensor. Crimp Deutsch sockets to both ends of each wire.
D. Connect one wire between P1:26 and terminal 1 of the coolant level sensor. Connect the other wire between P1:5 and terminal 2 of the coolant level sensor.
E. Turn the key switch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
Expected Result:
There are no active diagnostic codes.
Results:
• OK – There was a problem in the harness.
Repair: Perform the following repair:
1. Permanently replace the faulty wiring.
2. Clear all diagnostic codes.
3. Verify that the repair eliminates the problem.
STOP.
• Not OK – Bypassing the harness did not fix the problem.
Repair: If the problem is intermittent, refer to Troubleshooting, “Electrical Connectors – Inspect”.
Restart this procedure and carefully perform each step.
STOP.
