System Operation Description:
During normal operation, coolant is sent to the air intake system in order to cool the intake air. A jacket water aftercooler in the air lines after the turbochargers cools the air before the air enters the air-to-air aftercooler. When the vehicle is at idle in cold climates, the aftercooler may overcool the engine. The engine coolant diverter stops the flow of coolant to the aftercooler in order to prevent the coolant temperature from becoming too low. Diverting the coolant will also prevent the temperature in the cab from becoming too low.
“Coolant Diverter Valve Test”
The “Coolant Diverter Valve Test” is available to help diagnose problems with the engine coolant diverter solenoid. A small current is applied to the circuit at all times. This allows the Engine Control Module (ECM) to detect open circuits when the valve is not actuated. A short circuit will only be detected when the valve is actuated.
The following conditions must be met before the “Coolant Diverter Valve Test” will function:
• Engine speed is 0.
• Vehicle speed is 0.
• The neutral switch is in the Neutral position.
Test Step 1. Inspect Electrical Connectors and Wiring
A. Turn the key switch to the OFF position.
B. Thoroughly inspect the J2/P2 ECM connector and the solenoid connector. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.
C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the solenoid connector.
D. Check the ECM connector (allen head screw) for the proper torque of 6 N·m (55.0 lb in).
E. Check the harness and wiring for abrasion and for pinch points.
Expected Result:
All connectors, pins, and sockets are completely coupled and/or inserted and the harness and the wiring are free of corrosion, of abrasion, or of pinch points.
Results:
• OK – The electrical connectors and wiring are OK. Proceed to Test Step 2.
• Not OK – There is a problem with the electrical connectors and/or the wiring.
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.
STOP.
Test Step 2. Determine the Condition that is Present
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 that are related to the engine coolant diverter solenoid.
D. Start the “Coolant Diverter Valve Test” on Cat ET.
E. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve Test”.
Expected Result:
The test indicated “Not Active: Device Open” or “Not Active: Device Short”.
Results:
• Open – The test indicated “Not Active: Device Open”. Proceed to Test Step 3.
• Short – The test indicated “Not Active: Device Short”. Proceed to Test Step 7.
Test Step 3. Short the Wires at the Solenoid
A. Turn the key switch to the OFF position.
B. Disconnect the engine coolant diverter solenoid at the solenoid connector.
C. Fabricate a jumper wire to short terminal 1 and terminal 2 of the connector for the solenoid on the engine harness.
D. Turn the key switch to the ON position.
E. Access the “Special Tests” under the “Service” menu.
F. Start the “Coolant Diverter Valve Test” on Cat ET.
G. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve Test”.
Expected Result:
The test indicated “Not Active: Device Short” with the jumper wire in place.
Results:
• OK – The test indicated “Not Active: Device Short”. Proceed to Test Step 4.
• Not OK – The test indicated “Not Active: Device Open”.
Repair: Reconnect the solenoid to the solenoid connector.
Proceed to Test Step 5.
Test Step 4. Check the Resistance of the Solenoid
A. Turn the key switch to the OFF position.
B. Use a multimeter to measure the resistance between terminal 1 and terminal 2 of the engine coolant diverter solenoid.
Expected Result:
The resistance is less than 13 Ohms for 12 volt systems and the resistance is less than 50 Ohms for 24 volt systems.
Results:
• OK – The resistance is within the specifications.
Repair: Inspect the solenoid connector, terminals, and wiring.
Verify that all of the connectors, terminals, and wiring are OK.
If the problem is intermittent refer to Troubleshooting, “Electrical Connectors – Inspect”.
STOP.
• Not OK – The resistance is not within the specifications.
Repair: Temporarily connect a new solenoid.
If the new solenoid fixes the problem, reconnect the suspect solenoid.
If the problem returns, permanently replace the solenoid.
Verify that the repair eliminates the problem.
STOP.
Test Step 5. Short the Circuit at the ECM
A. Turn the key switch to the OFF position.
B. Disconnect the P2 ECM connector.
C. Remove the wires from P2:8 (Engine coolant diverter solenoid) and P2:53 (Solenoid common).
D. Fabricate a jumper wire to short P2:8 (Engine coolant diverter solenoid) and P2:53 (Solenoid common).
E. Reconnect the P2 ECM connector.
F. Turn the key switch to the ON position.
G. Access the “Special Tests” under the “Service” menu.
H. Start the “Coolant Diverter Valve Test” on Cat ET.
I. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve Test”.
Expected Result:
The test indicated “Not Active: Device Short” with the jumper wire in place.
Results:
• OK – The test indicated “Not Active: Device Short” with the jumper wire in place. Proceed to Test Step 6.
• Not OK – The test indicated “Not Active: Device Open” with the jumper wire in place.
Repair: Temporarily connect a test ECM.
If the test ECM fixes the problem, reconnect the suspect ECM.
If the problem returns, permanently replace the ECM.
Verify that the repair eliminates the problem.
STOP.
Test Step 6. Bypass the Harness
A. Turn the key switch to the OFF position.
B. Disconnect the P2 ECM connector and the P702 Engine coolant diverter solenoid connector.
C. Remove the wire from P2:8 (Engine coolant diverter solenoid) and P702:1 (Engine coolant diverter solenoid).
D. Fabricate two jumper wires that can reach from the ECM to the engine coolant diverter solenoid.
E. Insert one of the jumper wires into P2:8 and P702:1.
F. Turn the key switch to the ON position.
G. Access the “Special Tests” under the “Service” menu.
H. Start the “Coolant Diverter Valve Test” on Cat ET.
I. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve Test”.
J. Turn the key switch to the OFF position.
K. Disconnect the P2 ECM connector and the P702 Engine coolant diverter solenoid connector.
L. Remove the wire from P2:53 (Solenoid common) and P702:2 (Solenoid common).
M. Insert the other jumper wire into P2:53 and P702:2.
N. Turn the key switch to the ON position.
O. Access the “Special Tests” under the “Service” menu.
P. Start the “Coolant Diverter Valve Test” on Cat ET.
Q. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve Test”.
Expected Result:
The test indicates “Active” with one or both of the jumper wires in place.
Results:
• OK – The bypass harness repaired the problem.
Repair: Repair the suspect wires or replace the suspect wires.
Verify that the repair eliminates the problem.
STOP.
• Not OK – The bypass harness did not repair the problem.
Repair: Verify that the bypass harness is properly connected.
Check the ECM connector and the solenoid connector for damage and/or moisture.
If the problem is intermittent, refer to Troubleshooting, “Electrical Connectors – Inspect”.
STOP.
Test Step 7. Create an Open at the Solenoid
A. Turn the key switch to the OFF position.
B. Disconnect the engine coolant diverter solenoid at the solenoid connector.
C. Turn the key switch to the ON position.
D. Access the “Special Tests” under the “Service” menu.
E. Start the “Coolant Diverter Valve Test” on Cat ET.
F. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve Test”.
Expected Result:
The test indicates “Not Active: Device Open”.
Results:
• OK – The test indicates “Not Active: Device Open”. Proceed to Test Step 8.
• Not OK – The test indicates “Not Active: Device
Short”. Proceed to Test Step 9.
Test Step 8. Check the Resistance of the Solenoid
A. Turn the key switch to the OFF position.
B. Use a multimeter to measure the resistance between terminal 1 and terminal 2 of the engine coolant diverter solenoid.
Expected Result:
The resistance is greater than 5 Ohms for 12 volt systems and the resistance is greater than 23 Ohms for 24 volt systems.
Results:
• OK – The resistance is within the specifications.
Repair: Check the solenoid connector for corrosion and moisture.
If the problem is intermittent, refer to Troubleshooting, “Electrical Connectors – Inspect”.
STOP.
• Not OK – There is a short circuit in the solenoid.
Repair: Temporarily connect a new solenoid.
If the new solenoid fixes the problem, reconnect the suspect solenoid.
If the problem returns, permanently replace the solenoid.
Verify that the repair eliminates the problem.
STOP.
Test Step 9. Create an Open at the ECM
A. Turn the key switch to the OFF position.
B. Disconnect the P2 ECM connector.
C. Check the ECM connector for corrosion and moisture.
D. Remove the wires from P2:8 (Engine coolant diverter solenoid) and P2:53 (Solenoid common).
E. Reconnect the P2 ECM connector.
F. Turn the key switch to the ON position.
G. Access the “Special Tests” under the “Service” menu.
H. Start the “Coolant Diverter Valve Test” on Cat ET.
I. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve
Test”.
Expected Result:
The test indicates “Not Active: Device Open”.
Results:
• OK – The test indicates “Not Active: Device Open”. Proceed to Test Step 10.
• Not OK – The test indicates “Not Active: Device Short”.
Repair: Temporarily connect a test ECM.
If the test ECM fixes the problem, reconnect the suspect ECM.
If the problem returns, permanently replace the ECM.
Verify that the repair eliminates the problem.
STOP.
Test Step 10. Bypass the Harness
A. Turn the key switch to the OFF position.
B. Disconnect the P2 ECM connector and the P702 Engine coolant diverter solenoid connector.
C. Remove the wire from P2:8 (Engine coolant diverter solenoid) and P702:1 (Engine coolant diverter solenoid).
D. Fabricate two jumper wires that can reach from the ECM to the engine coolant diverter solenoid.
E. Insert one of the jumper wires into P2:8 and P702:1.
F. Turn the key switch to the ON position.
G. Access the “Special Tests” under the “Service” menu.
H. Start the “Coolant Diverter Valve Test” on Cat ET.
I. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve Test”.
J. Turn the key switch to the OFF position.
K. Disconnect the P2 ECM connector and the P702 Engine coolant diverter solenoid connector.
L. Remove the wire from P2:53 (Solenoid common) and P702:2 (Solenoid common).
M. Insert the other jumper wire into P2:53 and P702:2.
N. Turn the key switch to the ON position.
O. Access the “Special Tests” under the “Service” menu.
P. Start the “Coolant Diverter Valve Test” on Cat ET.
Q. Once Cat ET displays the status of the engine coolant diverter, stop the “Coolant Diverter Valve Test”.
Expected Result:
The test indicates “Active” with one or both of the jumper wires in place.
Results:
• OK – The bypass harness repaired the problem.
Repair: Repair the suspect wires or replace the suspect wires.
Verify that the repair eliminates the problem.
STOP.
• Not OK – The bypass harness did not repair the problem.
Repair: Verify that the bypass harness is properly connected.
Check the ECM connector and the solenoid connector for damage and/or moisture.
If the problem is intermittent, refer to Troubleshooting, “Electrical Connectors – Inspect”.
STOP.
