DISC ASSEM. 1S3736 - Caterpillar

System Operation Description:The CAN Data Link is used to communicate engine information and diagnostic information from the ECM. Test Step 1. Check for Connector Damage
Disconnect the main power.
Check the connectors and wiring for the following problems: damage, corrosion, abrasion and incorrect attachment.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: Replace the harness.STOPTest Step 2. Check the Voltage to the ECM.
Disconnect the ECM connector J1/P1.
Connect the Battery power to the ECM. Leave the Start/Run/Stop Switches disconnected.
Measure the voltage between P1-6 and P1-5.
Disconnect the main power.Expected Result:The voltage should be between 23 VDC and 25.5 VDC.Results:
OK - Proceed to test step 3.
Not OK - Repair: Refer to Troubleshooting, "Electrical Power Supply".STOPTest Step 3. Verify the Wiring.
Disconnect the ECM connector J1 and the J1939 display device.
Measure the resistance between J1-10 and J1-16. Wiggle the harness during the measurement in order to reveal an intermittent condition.Expected Result:The resistance should measure 60 3 Ohms.Results:
OK - Proceed to test step 4.
Not OK - The resistance is 120 6 Ohms.Repair: A terminating resistor must be added because a terminating resistor is missing. Refer to the Schematic.STOP
Not OK - The resistance is greater than 20,000 Ohms.Repair: There is an open circuit in the harness. Repair the harness and/or replace the harness.STOP
Not OK - The resistance is less than 10 Ohms.Repair: There is a short in the harness. Repair the harness and/or replace the harness.STOPTest Step 4. Check for a Short Circuit.
Leave J1 disconnected. Disconnect the two terminating resistors.
Measure the resistance between P1-10 and P1-4. Wiggle the harness during the measurement in order to reveal an intermittent condition.
Continue this procedure with the following combinations:
J1-10 and J1-5
J1-10 and J1-23
J1-10 and J1-15
J1-10 and Ground Stud (−Battery)
J1-11 and J1-4
J1-11 and J1-5
J1-11 and J1-23
J1-11 and J1-15
J1-11 and Ground Stud (−Battery)Expected Result:The resistance should be greater than 20,000 Ohms.Results:
OK - Proceed to test step 5.
Not OK - There is a short in the harness.Repair: Repair the harness and/or replace the harness.STOPTest Step 5. Check for an Open Circuit.
Make a jumper to short J1-10 to J1-11.
Measure the resistance between J1-10 and J1-11. Wiggle the harness during the measurement in order to reveal an intermittent condition.Expected Result:The resistance should be less than 10 Ohms.Results:
OK - Nothing is wrong at this time.STOP
Not OK - There is an open circuit in the harness.Repair: Repair the harness and/or replace the harness.STOP