0439209 JOHNSON CARBURETOR ASSY., Stbd., 115

Illustration 1 g00694476
SchematicTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Check the connectors and wiring for the following problems: damage, corrosion, abrasion and incorrect attachment. Pay close attention to the following areas:
ECM connector J1/P1
Connector for the J1939 Data Link
Connector for the terminating resistor
Wiring harness from the ECM back to the connector for the J1939 Data LinkRefer to Troubleshooting, "Electrical Connectors - Inspect" for more information.Expected Result:The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the J1939 Data Link circuit. Verify that the repair eliminates the problem. Stop.Test Step 2. Check Active Diagnostic Codes
Connect the Caterpillar Electronic Technician (Cat ET) to the service tool connector.
Turn the keyswitch to the ON position.
Monitor the screen for active diagnostic codes on Cat ET. Record any active diagnostic codes.Expected Result:No diagnostic codes are active.Results:
OK - There are no active diagnostic codes at this time.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if an intermittent problem is suspected. Stop.
Not OK - 247-09 is active. Proceed to Test Step 3.Test Step 3. Check the Input Voltage to the ECM
Turn the keyswitch to the ON position.
Use signal reading probes to measure the voltage between P1:48 and P1:61. Wiggle the harness during the measurement in order to reveal an intermittent condition.
Use Cat ET to check for the following logged diagnostic codes:
168-00
168-01
168-02Note: If any of the previous diagnostic codes are logged there could be an intermittent problem in the circuit for the input voltage to the ECM.Expected Result:The input voltage to the ECM should be within 1.0 VDC of the battery voltage.Results:
OK - Proceed to Test Step 4.
Not OK - Repair: Refer to Troubleshooting, "Electrical Power Supply Circuit - Test" and Electrical System Schematic. Make any necessary repairs. Stop.Test Step 4. Check resistance through the Harness
Turn the keyswitch to the OFF position.
Disconnect the J1/P1 ECM connector and the J1939 data link connector.
Measure the resistance between P1:34 and P1:50. Wiggle the harness during the measurement in order to reveal an intermittent condition.Expected Result:The resistance should measure 120 6 Ohms.Results:
OK - Proceed to Test Step 5.
Not OK - The resistance is greater than 126 Ohms. There is an open circuit in the harness or the terminating resistor is missing or open.Repair: Repair the harness and/or replace the harness. If the terminating resistor is missing or damaged, install a new resistor. Stop.
Not OK - The resistance is less than 114 Ohms.Repair: There is a short in the harness or the terminating resistor is shorted. Replace the harness or the terminating resistor. Stop.Test Step 5. Check for a Short Circuit
Leave the J1/P1 ECM connector and the J1939 data link disconnected.
Remove the terminating resistor.
Measure the resistance between P1:34 and P1:50. Wiggle the harness during the measurement in order to reveal an intermittent condition.
Continue this procedure with the following combinations:
P1:34 and pin A of J1939 +
P1:50 and pin B of J1939 -
P1:34 and the ground stud
P1:50 and the ground studExpected Result:The resistance should be greater than 20,000 Ohms.Results:
OK - Proceed to Test Step 6.
Not OK - There is a short circuit in the harness.Repair: Repair the harness and/or replace the harness. Stop.Test Step 6. Check for an Open Circuit
Short terminals A and B of the J1939 Data Link connector.
Measure the resistance between P1:34 and P1:50.
Remove the jumper wire from pin A and pin B on the J1939 Data Link connector.
Measure the resistance between P1:42 and pin C on the J1939 Data Link connector.
Reconnect the terminating resistor.Expected Result:The resistance should be less than 10 Ohms.Results:
OK - There are no open circuits in the harness. Proceed to Test Step 7.
Not OK - There is an open circuit in the harness.Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.Test Step 7. Use a Test ECM to Check the J1939 Data Link
Temporarily connect a test ECM.
Verify that the test ECM resolves the original problem.
If the problem is resolved with the test ECM in place, reconnect the suspect ECM.
If the problem returns with the suspect ECM in place, replace the ECM. Verify that the repair eliminates the problem.Results:
OK - The problem was resolved by replacing the ECM. Stop.
Not OK - The problem is in the data link adapter to the display module in the cab. Make any necessary repairs. Stop.