3500B Engines for Caterpillar Built Power Modules with the ADEM 3 Electronic Control Module Caterpillar

The Cat Data Link is used for communication between electronic modules. The Cat Data Link is used to communicate information from the Electronic Control Module (ECM) to the Electronic Monitoring System (EMS). The Cat Data Link is used for programming and troubleshooting the ECM.

The ECM communicates with the EMS in order to share engine information and diagnostics that may affect engine operation.

The ECM communicates with the Caterpillar Electronic Technician (ET) in order to share status and diagnostic information. The Cat ET can also be used to configure the ECM parameters on the engine. This information will not be available if communications fail between the ECM and the Cat ET.

Illustration 1	g01161814
Typical example

Test Step 1. Check for Connector Damage

1. Turn the engine control switch to the OFF/RESET mode. The engine should be off.

2. Turn the battery disconnect switch to the OFF position.

3. 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.

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

5. Check the ECM connectors (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors".

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

Expected Result:

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

Results:

• OK - The connectors and wiring are OK. Proceed to Test Step 2.

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

  Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring.

  STOP

Test Step 2. Check for Electrical Shorts in the Harness

1. Disconnect the ECM connector and disconnect the generator connector.

2. Disconnect any module that is connected to the Cat Data Link.

3. Measure the resistance at the following points. Wiggle the harness during the measurement in order to reveal an intermittent short.

   • Cat Data Link + to Cat Data Link −

   • Cat Data Link + to −Battery terminal

   • Cat Data Link − to −Battery terminal

   • Cat Data Link + to +Battery terminal

   • Cat Data Link − to +Battery terminal

   • Cat Data Link + to engine ground

   • Cat Data Link − to engine ground

Expected Result:

The resistance is greater than 20,000 Ohms for each measurement.

Results:

• OK - The resistance is greater than 20,000 Ohms. Proceed to Test Step 3.

• Not OK - The resistance is less than 20,000 Ohms. There is a short in the harness or in the connectors.

  Repair: Repair the connector and/or wiring or replace the connector and/or wiring.

  STOP

Test Step 3. Check the Resistance through the Harness for an Open Circuit

1. Turn the engine control to the OFF/RESET mode. The engine should be off.

2. Turn the battery disconnect switch to the OFF position.

3. Disconnect the ECM connector and the generator connector.

4. Disconnect any module that is connected to the Cat Data Link.

5. Short the wires of the Cat Data Link together. Create the short at P1-9 and P1-8 of the primary ECM connector.

6. Set an ohmmeter on the 200 ohm scale. Measure the resistance between the terminals of the Cat Data Link + and the Cat Data Link −. Measure the resistance at the connectors for the ECM. Measure the resistance between the terminals of any module that was connected to the Cat Data Link. Wiggle the harness during the measurements in order to reveal an intermittent open condition.

7. Short the wires of the Cat Data Link together. Create the short at Pin-13 and Pin-14 of the generator connector.

8. Reconnect all connectors and modules.

Expected Result:

The resistance is less than five Ohms for each measurement.

Results:

• OK - The resistance is less than five Ohms for each measurement.

  Repair: The harness is OK. There could be a problem with a module or with the ECM. Connect the suspect module on another engine. If the problem returns on the other engine, replace the suspect module. Turn the battery disconnect switch to the OFF position. Turn the battery disconnect switch to the ON position. If the diagnostic code is still present, replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".

  STOP

• Not OK - The resistance is greater than five Ohms for each measurement.

  Repair: There is an open circuit or there is excessive resistance in the harness. Repair the connectors and/or wiring or replace the connectors and/or wiring.

  STOP