C27 and C32 Engines for Caterpillar Built Machines Caterpillar

Coolant Flow - Test

Usage:

990K A9P

Use this procedure to troubleshoot the electrical system if a problem is suspected with the coolant flow switch. Also, use this procedure if one of the codes that are listed in Table 1 is active or logged.

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Table 1
CDL Code and Description	Conditions which Activate the Code	System Response
E563(3) Low Engine Coolant Flow	The coolant flow switch indicates that coolant flow has stopped. The coolant flow switch is in the open position.	The code is logged.
1937-2 Engine Coolant Flow Switch erratic, intermittent, or incorrect	The coolant flow switch indicates that coolant flow is intermittent.	The code is logged.

The coolant flow switch is a paddle switch that is used to detect the flow of coolant in the engine cooling system.

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Illustration 1	g01249790
Coolant flow switch (1) Flow switch assembly (2) Paddle

The coolant flow switch is a normally open switch. The contacts of flow switch assembly (1) close as coolant flow from the engine flows across paddle (2) of the switch. The Electronic Control Module (ECM) monitors the status of the coolant flow switch during engine operation. If the ECM detects a loss of coolant flow during operation, a signal will be sent in order to alert the operator of the condition.

The status of the "Engine Coolant Flow" can be monitored using Caterpillar Electronic Technician (ET) to determine the state of the coolant flow switch.

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Illustration 2	g02284736

Schematic for the coolant flow switch

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check the Coolant Level A. Ensure that the coolant level for the engine is correct.	Coolant Level	Result: The coolant level is OK. Proceed to Test Step 2. Result: The coolant level is low. Repair: Diagnose the reason for a low coolant level. Verify that the repair eliminates the problem.

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Illustration 3	g02301274
Location of the ECM connectors (3) J1/P1 ECM connector

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Illustration 4	g02301279
Location of the coolant flow switch (right front engine view) (4) Coolant flow switch

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Illustration 5	g03336343
Terminal locations at the P1 ECM connector for the coolant flow switch (P1-5) Return (P1-54) Coolant flow switch

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Illustration 6	g01155187
Terminal locations at the connector for the coolant flow switch (Terminal 1) Signal (Terminal 2) Return

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Table 3
Troubleshooting Test Steps	Values	Results
2. Inspect the Electrical Connectors and the Wiring A. Turn the keyswitch to the OFF position. B. Thoroughly inspect J1/P1 ECM connector (3) and the connector for coolant flow switch (4). 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 that are associated with the circuit. D. Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.	Electrical Connectors and Wiring	Result: The harness and wiring are OK. Proceed to Test Step 3. Result: There is a problem in the connectors and/or 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 coupled. Verify that the repair eliminates the problem. STOP
3. Use Cat ET to Monitor the Switch Status A. Connect Cat ET to the service tool connector. B. Turn the keyswitch to the ON position. C. Observe the status for "Engine Coolant Flow" on Cat ET. D. Start the engine. E. Observe the status for "Engine Coolant Flow" on Cat ET. F. Turn the keyswitch to the OFF position.	Switch Status	Result: Cat ET indicates "No Flow" while the engine is not running. Cat ET indicates "Flow" while the engine is running. Repair: The switch is operating correctly at this time. There may be an intermittent problem with the switch or the switch circuit. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect". Verify that the repair eliminates the problem. Result: Cat ET does not indicate "No Flow" while the engine is not running. Cat ET does not indicate "Flow" while the engine is running. Cat ET does not indicate the correct status for the coolant flow switch. Proceed to Test Step 4.
4. Create a Short at the Connector for the Coolant Flow Switch A. Disconnect the connector for the coolant flow switch. B. Fabricate a jumper wire that is long enough to create a short at the harness connector for the coolant flow switch. Crimp connector pins to each end of the jumper wire. C. Install the jumper wire to the terminals of the harness connector of the coolant level switch. D. Turn the keyswitch to the ON position. E. Observe the status of "Engine Coolant Flow" on Cat ET. F. Turn the keyswitch to the OFF position. Restore the wiring to the original configuration.	Coolant Flow Switch	Results: The status indicates "Flow" with the jumper wire in place. Proceed to Test Step 5. Results: The status indicates "No Flow" with the jumper wire in place. There is a problem in the harness between the ECM and the connector for the coolant flow switch. There may be a problem with the ECM. Proceed to Test Step 6.

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Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure.

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Table 4
Troubleshooting Test Steps	Values	Results
5. Check the Coolant Flow Switch A. Drain the engine coolant to a level that is below the coolant flow switch. B. Remove the coolant flow switch from the engine. C. Manually close the coolant flow switch. Ensure that the operation of the switch is smooth and ensure that the switch does not bind. D. Check for continuity between the terminals of the switch at the connector while the switch is closed.	Coolant Flow Switch	Result: The switch operates smoothly and there is continuity between the terminals while the switch is closed. Repair: The switch and the switch circuit are operating correctly. There may be a mechanical problem with the cooling system. Diagnose the cooling system. Refer to Systems Operation/Testing and Adjusting, "Cooling System". Verify that the repair eliminates the problem. Verify that the repair eliminates the problem. Result: The switch does not operate smoothly or there is not continuity between the terminals while the switch is closed. Repair: There is a problem with the coolant flow switch. Replace the coolant flow switch with a new switch. Verify that the repair eliminates the problem.
6. Check for the Correct Operation of the ECM A. Disconnect the J1/P1 ECM connector. B. Fabricate a jumper wire that is long enough to create a short between the ECM connector and the engine ground stud. Crimp a connector socket to one end of the jumper wire. C. Remove the wire from terminal location P1-54 at the ECM connector. Install the jumper wire into this terminal location. D. Reconnect the J1/P1 ECM connector. E. Connect the other end of the jumper wire to the engine ground stud. F. Turn the keyswitch to the ON position. G. Observe the status of "Engine Coolant Flow" on Cat ET. H. Remove the electrical power from the ECM. Restore the wiring to the original configuration.	ECM	Result: The status indicates "Flow" with the jumper wire in place. Repair: There is an open circuit in the harness between the ECM connector and the connector for the coolant flow switch. Repair the wiring harness. Replace parts, if necessary. Verify that the repair eliminated the original problem. STOP Repair: The status indicates "No Flow" with the jumper wire in place. Repair: The ECM is not detecting the correct switch status. There may be a problem with the ECM. Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN). Verify that the repair eliminates the problem.