ARM AS-SCISSORS 3662574 - Caterpillar

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SchematicTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Thoroughly inspect ECM connector J2/P2 and all other connectors in the wiring harness. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.Expected Result:All connectors, pins, and sockets should be completely inserted and coupled. The harness and wiring should be free of corrosion, abrasion, and pinch points. All connections and grounds should be tight and free of corrosion.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Resistance through the Solenoid
Disconnect fan control solenoid connector J41/P41.
Measure the resistance between J41:1 (Fan Control Solenoid) and J41:2 (Solenoid Return).Expected Result:Resistance should be between 2 and 4.6 Ohms.Results:
OK - Proceed to Test Step 4.
Not OK - There may be a problem with the fan control solenoid. Proceed to Test Step 3.Test Step 3. Temporarily Install a New Fan Control Solenoid
Remove the fan control solenoid.
Temporarily install a new fan control solenoid.
Start the engine. Ensure that the keyswitch is in the ON position.
Compare the status for "Engine Fan Speed" to the status for "Desired Engine Fan Speed" on ET.
Turn the keyswitch to the OFF/RESET position.Expected Result:"Engine Fan Speed" should be within 50 rpm of "Desired Engine Fan Speed".Results:
OK - The fan control solenoid was faulty.Repair: Permanently install the new fan control solenoid.Verify that the repair eliminates the problem.STOP
Not OK - There may be a problem with the harness. Proceed to Test Step 4.Test Step 4. Check for Shorts in the Harness
Illustration 2 g00677768
ECM connector P2
Disconnect ECM connector J2/P2.
Disconnect fan control solenoid connector J41/P41.
Measure the resistance between P2:19 (Fan Control Solenoid) and chassis ground.
Measure the resistance between P2:7 (Solenoid Return) and chassis ground.
Measure the resistance between P2:19 (Fan Control Solenoid) and P2:7 (Solenoid Return).Expected Result:The resistance for each measurement should be greater than 20,000 Ohms.Results:
OK - Proceed to Test Step 5.
Not OK - There is a short between the ECM and the fan control solenoid.Repair: Repair the circuit.STOPTest Step 5. Check for Open Circuits in the Harness
Illustration 3 g00677768
J2/P2 breakout
Turn the keyswitch to the OFF/RESET position and install a 7X-1715 Adapter Cable (40 Pin Breakout) at ECM connector J2/P2.
Use a suitable piece of wire to short P2:19 (Fan Control Solenoid) and P2:7 (Solenoid Return) at the breakout.
Disconnect fan speed control solenoid connector J41/P41.
Measure the resistance between P41:1 (Fan Control Solenoid) and P41:2 (Solenoid Return).Expected Result:The resistance should be less than 10 Ohms.Results:
OK - Proceed to Test Step 6.
Not OK - There is an open circuit in the wiring harness between the fan control solenoid and the ECM.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 6. Compare the Actual Fan Speed to the Desired Fan Speed
Start the engine.
Compare the status for "Engine Fan Speed" to the status for "Desired Engine Fan Speed" on ET.
Turn the keyswitch to the OFF/RESET position.Expected Result:"Engine Fan Speed" should be within 50 rpm of "Desired Engine Fan Speed".Results:
OK - The system is functioning correctly.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect"