5031431 JOHNSON VALVE, IAC

Illustration 1 g01251396
Schematic for the engine cooling fan's bypass solenoidTest Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Turn the battery disconnect switch to the OFF position.
Illustration 2 g01186024
Location of the J1/P1 ECM connectors (typical left side engine view)
Thoroughly inspect the J1/P1 ECM connectors. Also, thoroughly inspect all of the other connectors for the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01416322
Terminal locations at the P1 ECM connector for the engine cooling fan's bypass solenoid (P1-18) Digital return (P1-19) Bypass solenoid
Illustration 4 g01155187
Terminal locations at the solenoid connector for the engine cooling fan's bypass solenoid (Terminal 1) Bypass solenoid (Terminal 2) Digital return
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 allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
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 2. Check for Logged Diagnostic Codes
Turn the battery disconnect switch to the ON position.
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the keyswitch to the ON position.
Check for logged diagnostic codes for the bypass solenoid for the engine cooling fan on Cat ET. Record any logged diagnostic codes.
Determine if the problem is related to an open circuit diagnostic code 05 or a short circuit diagnostic code 06.
Turn the keyswitch to the OFF position.Expected Result:A short circuit diagnostic code (06) is logged.Results:
OK - A short circuit diagnostic code (06) is logged at this time. Proceed to Test Step 3.
Not OK - An open circuit diagnostic code (05) is logged at this time. Proceed to Test Step 5.Test Step 3. Check for a Short in the Harness
Disconnect the J1/P1 ECM connector.
Disconnect the connector for the bypass solenoid for the engine cooling fan.
Check the resistance between terminals P1-18 and P1-19 at the ECM connector.
Check the resistance between terminal P1-18 and all of the other terminals in the ECM connector. Also, check the resistance between terminal P1-18 and the engine ground stud.
Check the resistance between terminal P1-19 and all of the other terminals in the ECM connector. Also, check the resistance between terminal P1-19 and the engine ground stud.The correct measurement for each resistance check is an open circuit condition. Expected Result:There are no shorts in the harness. Results:
OK - There are not any shorts in the harness. Proceed to Test Step 4.
Not OK - There is a short in the harness.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 4. Check for a Short in the Coil of the Bypass Solenoid
Measure the resistance between terminal 1 and terminal 2 at the connector for the bypass solenoid for the engine cooling fan.
Restore all of the wiring to the original configuration.Expected Result:The resistance is between 24 and 53 Ohms.Results:
OK - The resistance is between 24 and 53 Ohms.Repair: The resistance of the solenoid coil is correct. Check for a short to ground at each terminal of the solenoid:
Check continuity between terminal 1 and engine ground.
Check continuity between terminal 2 and engine ground.If a short to engine ground is found, replace the bypass solenoid for the engine cooling fan.If no short is found, reconnect the connectors to the original configuration. Run the engine and check for diagnostic codes. If necessary, retest the circuit.STOP
Not OK - The resistance is not between 24 and 53 Ohms. There is a short in the coil of the bypass solenoid for the engine cooling fan.Repair: Replace the bypass solenoid for the engine cooling fan.STOPTest Step 5. Check for an Open in the Harness
Disconnect the harness connectors at the bypass solenoid.
Fabricate a jumper wire that is long enough to create a short circuit across the terminals of the solenoid connector. Crimp connector sockets to each end of the jumper wire.
Install the jumper wire to the terminals that are for the harness side of the solenoid connector.
Disconnect the J1/P1 ECM connectors.
Check for continuity between terminals P1-18 and P1-19 at the ECM connector.
Remove the jumper wire.Expected Result:There is not an open in the harness.Results:
OK - There is not an open in the harness. Proceed to Test Step 6.
OK - There is an open in the harness.Repair: Repair the connectors or wiring and/or rep