0341220 JOHNSON SCREW, Pitot tube plug

Illustration 1 g01006329
Schematic
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P1 ECM Connector
Illustration 3 g00810608
Sensor connectorTest Step 1. Disconnect the ECM Connector and Check for Active Diagnostic Codes
Turn the keyswitch to the OFF position.
Connect the Caterpillar Electronic Technician (Cat ET) to the data link connector.
Disconnect the P2 ECM connector from the ECM.
Check the ECM connector for corrosion and for moisture.
Turn the keyswitch to the ON position.
Check for active diagnostic codes on Cat ET.Expected Result:The 5 volt diagnostic codes are not active. An open circuit diagnostic code is active for all of the analog sensors.Results:
OK - The 5 volt diagnostic codes are not active.Repair: Reconnect the P2 ECM connector. Proceed to Test Step 2.
Not OK - The 5 volt diagnostic codes are still active.Repair: Connect a test ECM.If the test ECM fixes the problem, reconnect the suspect ECM.If the problem returns, permanently install the new ECM.Verify that the repair eliminates the problem. Stop.Test Step 2. Disconnect the Sensors
Turn the keyswitch to the ON position.
Monitor the active diagnostic code screen on Cat ET.
Disconnect the analog sensors one at a time. Wait for 30 seconds after each analog sensor is disconnected.Note: The 5 volt diagnostic code will become inactive if a analog sensor is the cause of the 5 volt diagnostic code.
Ensure that all of the analog sensors are disconnected.Expected Result:The 5 volt diagnostic code is still active when all of the analog sensors are disconnected.Results:
OK - The 5 volt diagnostic code is still active.Repair: Leave all of the analog sensors disconnected. Proceed to Test Step 4.
Not OK - The 5 volt diagnostic code disappears when the analog sensors are disconnected. Repair: Reconnect all of the analog sensors except the suspect sensor. Proceed to Test Step 3.Test Step 3. Check the Signal Wire
Turn the keyswitch to the ON position.Note: The suspect sensor should be disconnected.
Measure the voltage between terminal C (Signal) and terminal B (Sensor Return) of the connector for the suspect sensor on the engine harness.Expected Result:The voltage is less than 7.0 VDC.Results:
OK - The voltage is within the range.Repair: Temporarily connect a new sensor.If the problem is resolved with the new sensor, reconnect the suspect sensor.If the problem returns, replace the suspect sensor.Verify that the repair eliminates the problem. Stop.
Not OK - The voltage is greater than 7.0 VDC.Repair: Inspect the signal wire for a short circuit to a voltage source.Repair the signal wire or replace the signal wire.Verify that the repair eliminates the problem. Stop.Test Step 4. Determine the Condition that is Present
Turn the keyswitch to the ON position.
Access the active diagnostic code screen on Cat ET.Expected Result:262-03 or 262-04 is active.Results:
262-03 - Proceed to Test Step 5.
262-04 - Proceed to Test Step 7.Test Step 5. Measure the 5 Volt Supply to the Sensor
Turn the keyswitch to the ON position.Note: All of the analog sensors should be disconnected.
Measure the voltage between terminal A (Analog Sensor +5V) and chassis ground for each analog sensor.Expected Result:The voltage is 5.0 0.16 VDC.Results:
OK - The 5 volt supply is within the range. Proceed to Test Step 6.
Not OK - The voltage is greater than 5.16 volts.Repair: Check the 5 volt supply wire for a short to a higher voltage source.Repair the 5 volt supply wire or replace the 5 volt supply wire.Verify that the repair eliminates the problem. Stop.Test Step 6. Check the Return Wire
Turn the keyswitch to the ON position.
Measure the voltage between terminal A (Analog Sensor +5V) and terminal B (Sensor Return) on all of the analog sensors.
While the voltage is monitored, perform a 45 N (10 lb) pull test on the return wires for the 5 volt supply.
P1:30 (Sensor Return)Expected Result:The voltage is 5.0 0.16 VDC.Results:
OK - The voltage is within the range.Repair: If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect". Stop.
Not OK - The voltage is not within the range.Repair: Inspect the return wire for an open circuit.Repair the return wire or replace the return wire.Verify that the repair eliminates the problem. Stop.Test Step 7. Check the Resistance of the Harness
Turn the keyswitch to the OFF position.
Verify that all of the sensors are disconnected.
Measure the resistance between terminal A (Analog Sensor +5V) and terminal B (Sensor Return) of each connector for the analog sensor on the engine harness.Expected Result:The resistance is greater than 20,000 Ohms, or "OL" is displayed on the multimeter.Results:
OK - The 5 volt supply and the sensor return are not shorted.Repair: Check the 5 volt supply for a short to ground.Repair the 5 volt supply wire or replace the 5 volt supply wire.Verify that the repair eliminates the problem. Stop.
Not OK - There is a short between the 5 volt supply and the sensor return.Repair: Locate the short between the 5 volt supply and the sensor return.Repair the faulty wiring or replace the faulty wiring.Verify that the repair eliminates the problem. Stop.