0321643 JOHNSON BOLT

Illustration 1 g00844899
Typical circuit schematic for the fuel level sensors
The return wire may be connected to P1-3, P1-5, or P1-18.
Illustration 2 g01151126
Pin location on ECM connector
(P1-3) Sensor common
(P1-15) Primary fuel tank level
(P1-26) Secondary fuel tank level Test Step 1. Inspect Electrical Connectors and Wiring
Thoroughly inspect the J1/P1 ECM connector and the terminals for the fuel level sensors in the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the fuel level sensors.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and wiring for abrasion and pinch points from the sensors to the ECM. Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - 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. Clear all diagnostic codes.STOPTest Step 2. Determine the Condition that is Present
Connect Caterpillar Electronic Technician (ET) to the data link connector.
Turn the key switch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
Monitor the "Active Diagnostic Code" screen on Cat ET for diagnostic codes that are related to the fuel level sensors. Expected Result:A short circuit diagnostic code 04 is active or an open circuit diagnostic code 03 is active.Results:
Voltage Low - A short circuit diagnostic code 04 is active at this time. Proceed to Test Step 3.
Voltage High - An open circuit diagnostic code 03 is active at this time. Proceed to Test Step 4.Test Step 3. Disconnect the Sensor in order to Create an Open Circuit
Turn the key switch to the OFF/RESET position.
Disconnect the connector of the sensor with the short circuit diagnostic code.
Turn the key switch to the ON position. Wait at least 15 seconds for activation of the diagnostic codes.
Monitor the "Active Diagnostic Code" screen on Cat ET. Expected Result:An open circuit diagnostic code 03 for the disconnected sensor is now active.Results:
OK - A short circuit diagnostic code 04 was active before disconnecting the sensor. An open circuit diagnostic code 03 became active after disconnecting the sensor. Proceed to Test Step 5.
Not OK - There is a short circuit between the sensor harness connector and the ECM. Leave the sensor disconnected. Proceed to Test Step 7.Test Step 4. Measure the Sensor Supply Voltage
Turn the key switch to the OFF/RESET position.
Disconnect the suspect sensor from the harness at the fuel tank.
Turn the key switch to the ON position.
Measure the voltage between the two terminals of the fuel level sensor. Expected Result:The voltage is 4.5 to 5.5 VDC.Results:
OK - The sensor supply voltage is correct. Proceed to Test Step 6.
Not OK - The sensor supply voltage is out of the acceptable range. Continue testing the sensor supply circuit. Proceed to Test Step 7.Test Step 5. Determine if the Short Circuit is in the Connector or in the Sensor
Thoroughly inspect the connector for moisture.
Inspect the seals and reconnect the sensor.
If the short circuit diagnostic code reappears, the sensor or the harness connector is the problem.
Temporarily connect a new sensor to the harness.
Check for a short circuit diagnostic code 04 while the new sensor is connected to the harness. Expected Result:The short circuit diagnostic code 04 is not present when a new sensor is connected.Results:
OK - Verify that the repair eliminates the problem. Clear the logged diagnostic codes.STOP
Not OK - Repair the engine harness connector.STOPTest Step 6. Create a Short Circuit at the Sensor
Fabricate a jumper wire 150 mm (6 inch) long.
Turn the key switch to the ON position.
Insert the jumper wire between the two terminals at the connector for the suspect sensor on the vehicle harness.
Monitor the "Active Diagnostic Code" screen before installing the jumper wire and after installing the jumper wire. Expected Result:A short circuit diagnostic code 04 is active when the jumper is installed. An open circuit diagnostic code 03 is active when the jumper is removed.Results:
OK - The engine harness and the ECM are OK.Repair: Perform the following repair:
Temporarily connect the suspect sensor.
If the diagnostic code remains active, replace the sensor.
Ensure that the diagnostic code is no longer active.
Verify that the repair eliminates the problem. STOP
Not OK - The open circuit diagnostic code 03 remains active when the jumper is installed. The most probable location for the open is in the sensor common or in the sensor supply in the vehicle harness between the ECM and the sensor. Remove the jumper. Proceed to Test Step 7.Test Step 7. Check the ECM
Illustration 3 g01151140
Breakout T
(3) Sensor common
(15) Secondary fuel tank level
(26) Primary fuel tank level
Turn the key switch to the OFF/RESET position.
Disconnect the J1/P1 ECM connector. Thoroughly inspect both halves of the J1/P1 ECM connector for signs of corrosion or moisture.
Install a 140-2266 Cable (Seventy-Pin Breakout) between the J1 and P1 ECM connectors.
Turn the key switch to the ON position. Monitor the "Active Diagnostic Code" screen on Cat ET. Wait at least 15 seconds for activation of the code. An open circuit diagnostic code 03 should be active for the suspect sensor.
Fabricate a jumper wire 150 mm (6 inch) long. Crimp a Deutsch Socket to both ends of the wire.
Install the jumper wire at the breakout T. Insert the jumper wire between the terminal for the suspect sensor supply and the common connection for the sensor. A short circuit diagnostic code 04 should be active when the jumper wire is installed.Refer to Illustration 3 for the breakout T.Expected Result:An open circuit diagnostic code 03 is active when the jumper wire is removed. A short circuit diagnostic code 04 is active when the jumper wire is installed.Results:
OK - The ECM is operating properly. There may be an intermittent problem in the wiring between the ECM and the