3512B Petroleum Engines with the ADEM 2 Electronic Control Module Caterpillar

The CAN Data Link is used to communicate information from the Electronic Control Module (ECM). This allows the sharing of engine information and electronic system diagnostics.

Test Step 1. Check for Connector Damage.

1. Disconnect the main power.

2. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.

3. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.

4. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

5. Check the customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

6. Check the harness and the wiring for abrasion and pinch points.

Expected Result:

All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring should be free of corrosion, abrasion or pinch points.

Results:

• OK - The connectors and wiring are okay. Proceed to test step 2.

• Not OK - The connectors and/or wiring need repair.

  Repair: Replace the harness.

  STOP

Test Step 2. Check the Voltage to the ECM.

1. Disconnect the ECM connector J1/P1.

2. Connect the Battery power to the ECM. Leave the Start/Run/Stop Switches disconnected.

3. Measure the voltage between P1-6 and P1-5.

4. Disconnect the main power.

Expected Result:

The voltage should be 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to test step 3.

• Not OK - The voltage is not 24 ± 3 VDC.

  Repair: Perform the diagnostic functional test Troubleshooting, "Electrical Power Supply".

  STOP

Test Step 3. Verify the Wiring.

1. Disconnect the ECM connector P1 and the J1939 display device.

2. Measure the resistance between P1-10 and P1-16. Wiggle the harness during the measurement in order to reveal an intermittent condition.

Expected Result:

The resistance should measure 60 ± 3 ohms.

Results:

• OK - The resistance measures 60 ± 3 ohms. 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.

  STOP

Test Step 4. Check for a Short Circuit.

1. Leave P1 disconnected. Disconnect the two terminating resistors.

2. Measure the resistance between P1-10 and P1-4. Wiggle the harness during the measurement in order to reveal an intermittent condition.

3. Continue this procedure with the following combinations:
   • P1-10 and P1-5

   • P1-10 and P1-23

   • P1-10 and P1-15

   • P1-10 and − Battery terminal

   • P1-16 and P1-4

   • P1-16 and P1-5

   • P1-16 and P1-23

   • P1-16 and P1-15

   • P1-16 and − Battery terminal

Expected Result:

The resistance should be greater than 20,000 ohms.

Results:

• OK - The resistance is greater than 20,000 ohms. Proceed to test step 5.

• Not OK - The resistance is less than 20,000 ohms.

  Repair: There is a short in the harness. Repair the harness and/or replace the harness.

  STOP

Test Step 5. Check for an Open Circuit.

1. Make a jumper to short P1-10 to P1-16.

2. Measure the resistance between wire F711-GN and F712-GY at the J1939 display device. 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 - The resistance is less than 10 ohms.

  Repair: Nothing is wrong at this time.

  STOP

• Not OK - The resistance is greater than 10 ohms.

  Repair: There is an open circuit in the harness. Repair the harness and/or replace the harness.

  STOP