F8074 Force VENT SCREW WASHER

Illustration 1 g00840097
SchematicTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Thoroughly inspect the J1/P1 ECM connector, the J3/P3 machine connector, 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
Turn the keyswitch to the OFF/RESET position.
Disconnect the push/pull solenoid for the variable pitch fan.
Measure the resistance between J160:1 (Push Solenoid) and J160:2 (Digital Return).
Measure the resistance between J160:4 (Pull Solenoid) and J160:3 (Digital Return).Expected Result:Resistance should be 25 5 Ohms.Results:
OK - The push/pull solenoid for the variable pitch fan has the correct resistance. Proceed to Test Step 3.
Not OK - The push/pull solenoid for the variable pitch fan is faulty.Repair: Install a new push/pull solenoid for the variable pitch fan.Verify that the repair eliminates the problem.STOPTest Step 3. Check the Status of the Manual Purge Switch on ET
Connect ET to the service tool connector.
Turn the keyswitch to the ON position.
Observe the status for "Engine Fan Manual Purge Switch" on ET while you operate the switch.
Turn the keyswitch to the OFF/RESET position.Expected Result:The status of the switch should be "On" when the switch is depressed. The status should read "Off" when the switch is released.Results:
OK - The manual purge switch is working properly. Proceed to Test Step 5.
Not OK - The ECM does not recognize the input from the manual purge switch. Proceed to Test Step 4.Test Step 4. Check the Manual Purge Switch
Turn the keyswitch to the OFF/RESET position.
Disconnect the J161/P161 manual purge switch connector.
Measure continuity between P161:A (Manual Purge Switch) and P161:B (Digital Return) with the manual purge switch in the released position.
Measure continuity between P161:A (Manual Purge Switch) and P161:B (Digital Return) with the manual purge switch in the depressed position.Expected Result:There should be no continuity between P161:A (Manual Purge Switch) and P161:B (Digital Return) when the switch is in the released position. There should be continuity between P161:A (Manual Purge Switch) and P161:B (Digital Return) when the switch is in the depressed position.Results:
OK - There is no continuity when the switch is in the released position. There is continuity when the switch is in the depressed position. Proceed to Test Step 5.
Not OK - There is a problem with the manual purge switch.Repair: Replace the manual purge switch with a new switch.Verify that the repair eliminates the problem.STOPTest Step 5. Check for Shorts in the Harness for the Variable Pitch Fan
Illustration 2 g00840099
The P1 ECM connector
Disconnect the J1/P1 ECM connector.
Disconnect the J160/P160 push/pull solenoid connector.
Disconnect the J161/P161 manual purge switch connector.
Measure the resistance between P1:22 (Manual Purge Switch) and chassis ground.
Measure the resistance between P1:28 (Pull Solenoid) and chassis ground.
Measure the resistance between P1:34 (Push Solenoid) and chassis ground.
Measure the resistance between P1:22 (Manual Purge Switch) and P1:29 (Digital Return).
Measure the resistance between P1:28 (Pull Solenoid) and P1:29 (Digital Return).
Measure the resistance between P1:34 (Push Solenoid) and P1:29 (Digital Return).
Measure the resistance between P1:22 (Manual Purge Switch) and P1:28 (Pull Solenoid).
Measure the resistance between P1:22 (Manual Purge Switch) and P1:34 (Push Solenoid).
Measure the resistance between P1:28 (Pull Solenoid) and P1:34 (Push Solenoid).Expected Result:The resistance for each measurement should be greater than 20,000 Ohms.Results:
OK - There are no shorts in the harness. Proceed to Test Step 6.
Not OK - There is a short between the ECM and the push/pull solenoid and/or the manual purge switch.Repair: Repair the circuit.STOPTest Step 6. Check for Open Circuits in the Harness for the Variable Pitch Fan
Illustration 3 g00840099
J1/P1 breakout
Turn the keyswitch to the OFF/RESET position and disconnect the J1/P1 ECM connector.
Use a suitable piece of wire to short P1:22 (Manual Purge Switch) and P1:29 (Digital Return).
Disconnect the J160/P160 push/pull solenoid connector.
Disconnect the J161/P161 manual purge switch connector.
Measure the resistance between J161:B (Manual Purge Switch) and J161:C (Digital Return).
Use a suitable piece of wire to short P1:28 (Pull Solenoid) and P1:29 (Digital Return).
Measure the resistance between P160:4 (Pull Solenoid) and P160:3 (Digital Return).
Use a suitable piece of wire to short P1:34 (Push Solenoid) and P1:29 (Digital Return).
Measure the resistance between P160:1 (Push Solenoid) and P160:2 (Digital Return).
Remove all shorts and reconnect all connectors.Expected Result:The resistance should be less than 10 Ohms.Results:
OK - The wiring harness for the variable pitch fan is operating correctly. The ECM is not sending the correct signal to the push/pull solenoid for the variable pitch fan.Repair: Verify your results. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM.Verify that the repair eliminates the problem.STOP
Not OK - There is an open circuit between the ECM and the push/pull solenoid and/or the manual purge switch.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOP