0334852 JOHNSON PLATE - U

Illustration 1 g01259847
Schematic
Illustration 2 g01139422
P1 ECM connector
(P1-18) Common
(P1-44) Coolant flow switch
Illustration 3 g01140226
Typical location of coolant flow switch
(1) Coolant flow switch Test Step 1. Verify that the Coolant Level is Correct
Ensure that the coolant level for the engine is correct. Refer to the Operation and Maintenance Manual. Expected Result:The coolant is at an acceptable level.Results:
OK - The coolant is at an acceptable level. Proceed to Test Step 2.
Not OK - The coolant is low.Repair: Diagnose the reason for a low coolant level.Refer to Systems Operation/Testing and Adjusting, "Cooling System".Verify that the repair eliminates the problem.STOPTest Step 2. Inspect Electrical Connectors and Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the J1/P1 ECM connector and the connector for the coolant flow switch. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are free of corrosion, of abrasion, and of pinch points. All connections and grounds are tight and free of corrosion.Results:
OK - The harness and wiring are OK. Proceed to Test Step 3.
Not OK - 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 completely coupled.Verify that the repair eliminates the problem.STOPTest Step 3. Check the Status of the Coolant Flow on the Caterpillar Electronic Technician (ET)
Restore the electrical power to the ECM.
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Observe the reading for coolant flow on the Cat ET.
Start the engine.
Observe the reading for coolant flow on the Cat ET.
Remove the electrical power from the ECM. Expected Result:Cat ET indicates "NO FLOW" while the engine is not running. Cat ET indicates "FLOW" while the engine is running.Results:
OK - Cat ET indicates "NO FLOW" while the engine is not running. Cat ET indicates "FLOW" while the engine is running. The switch is OK.Repair: If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - 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 of the coolant flow switch. Proceed to test step 4.Test Step 4. Create a Short Circuit at the Connector of the Coolant Flow Switch
Remove the electrical power from the ECM.
Connect Cat ET to the service tool connector.
Disconnect the connector for the coolant flow switch.
Use a suitable piece of wire to short 1 (coolant flow switch) to 2 (return).
Restore the electrical power to the ECM.
Observe the status of "Engine Coolant Flow" on Cat ET.
Remove the electrical power from the ECM. Expected Result:The status indicates "Flow" with the jumper wire in place.Results:
OK - The ECM and the wiring are operating correctly. Proceed to Test Step 5.
Not OK - The status indicates "NO FLOW". Proceed to Test Step 6.Test Step 5. Check the Coolant Flow Switch
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.
Drain the engine coolant below the coolant flow switch.
Remove the coolant flow switch from the engine.
Manually close the coolant flow switch. Ensure that excessive force is not required to close the switch.
Measure continuity between 1 and 2 with the switch in the closed position. Expected Result:The switch closes easily and there is continuity between 1 and 2 with the switch in the closed position.Results:
OK - There may be a mechanical problem with the cooling system of the engine.Repair: Diagnose the cooling system of the engine. Refer to Systems Operation/Testing and Adjusting, "Cooling System".Verify that the repair eliminates the problem.STOP
Not OK - There is a problem with the coolant flow switch.Repair: Replace the coolant flow switch with a new switch.Verify that the repair eliminates the problem.STOPTest Step 6. Check the ECM
Disconnect the J1/P1 ECM connector.
Remove the wire from ECM connector P1-44. Install a wire with sockets on each end into P1-44.
Reconnect the J1/P1 ECM connector.
Use a suitable piece of wire to short the wire jumper in P1-44 to engine ground.
Restore the electrical power to the ECM.
Observe the status of "Engine Coolant Flow" on Cat ET.
Remove the electrical power from the ECM. Expected Result:The status indicates "Flow" with the jumper wire in place.Results:
OK - The status indicates "Flow" with the jumper wire in place.Repair: There is an open in the wire between 1 and the ECM and/or there is an open in the wire between 2 and the ECM. Repair the wire.STOP
Not OK - The status indicates "NO FLOW". The ECM is not responding correctly.Repair: Verify your results.Temporarily connect a test ECM.If the test ECM fixes the problem, reconnect the suspect ECM.If the problem returns, replace the ECM.Refer to electronic troubleshooting Troubleshooting, "Replacing the ECM".Verify that the repair eliminates the problem.STOP