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| Illustration 1 | g00822988 |
Part of the Schematic of the Cat Data Link | |
This diagnostic code is recorded when the Power Train ECM cannot communicate with the Caterpillar Monitoring System via the CAT Data Link. The update rate from the ECM is not correct.
The CAT Data Link is an input and an output of all modules. The CAT Data Link is designed to enable communications for all electronic control modules and service tools. The CAT Data Link is not a visible component. The data link consists of internal control circuits and the connecting harness wiring.
Test Step 1. CHECK THE COMPATIBILITY OF THE SOFTWARE.
- Verify that the software is compatible.
Expected Result:
The software is compatible.
Results:
- OK - The software is compatible. Proceed to test step 2.
- NOT OK - The software is NOT compatible.
Repair: Install the correct software. Ensure that the correct part number was used if any electronic control modules have been replaced. Continue if the conditions are not resolved.
Stop.
Test Step 2. CHECK THE +BATTERY CIRCUIT.
- Turn the key start switch and the disconnect switch to the OFF position.
- Disconnect connector J2 from the ECM.
- Turn the disconnect switch and the key start switch to the ON position.
- At connector J2, measure the voltage from +battery terminals to the negative battery terminals.
Expected Result:
The voltage should measure 18 to 35 DCV.
Results:
- OK - The voltage is correct. The ECM is receiving the voltage. Proceed to test step 3.
- NOT OK - The voltage does NOT measure 18 to 35 DCV.
Repair: The ECM is NOT receiving the correct voltage. Ensure that proper ground is available. If the ground is correct, repair the power circuit. Also, check the circuit breakers.
If conditions are not resolved proceed to test step 3.
Test Step 3. CHECK THE DATA LINK CIRCUIT FOR A SHORT TO GROUND.
- Turn the key start switch and the disconnect switch to the OFF position.
- Inspect the machine harness connectors that are related to the circuits of the CAT Data Link. Ensure that the connector contacts are clean and tight.
- Disconnect the machine harness from all modules.
- At the machine harness connector for the ECM, measure the resistance from contact J1-3 (wire 945-BR) and contact J1-9 (wire 944-OR) to all possible sources of ground.
Expected Result:
The resistance should be greater than 5000 ohms for each measurement.
Results:
- OK - The resistance measurement is correct. The machine harness is correct. Proceed to test step 4.
- NOT OK - The resistance measurement is not correct.
Repair: There is a short in the machine harness. The short is between J1-3 (wire 945-BR) and the circuit with the low resistance measurement or the short is between J1-9 (wire 944-OR) and the circuit with the low resistance measurement. Repair the harness or replace the harness. If conditions are not resolved, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace". If the problem remains present, exit this procedure and perform this procedure again.
Stop.
Test Step 4. CHECK THE CAT DATA LINK FOR A SHORT TO POSITIVE VOLTAGE.
- The key start switch and the disconnect switch remain in the OFF position.
- All modules remain disconnected from the machine harness.
- At the machine harness connector for the ECM, measure the resistance from contact J1-3 and contact J1-9 to all possible sources of positive voltage.
Expected Result:
The resistance measurement should be greater than 5000 ohms for each measurement.
Results:
- OK - The resistance is correct. The machine harness is correct. Proceed to test step 5 .
- NOT OK - The resistance is not correct.
Repair: There is a short in the machine harness. The short is between connector contact J1-7 and the circuit with the low resistance measurement or the short is between connector contact J1-8 and the circuit with the low resistance measurement. Repair the harness or replace the harness. If conditions are not resolved replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
Stop.
Test Step 5. CHECK THE CAT DATA LINK FOR AN OPEN CIRCUIT.
- The key start switch and the disconnect switch remain in the OFF position.
- At the ECM, measure the resistance from contact J1-7 (wire 945-BR) to the corresponding contact 14 (wire 945-BR) of the Caterpillar Monitoring System.
- At the ECM, measure the resistance from connector contact J1-8 (wire 944-OR) to the corresponding connector contact 5 (wire 944-OR) of the Caterpillar Monitoring System.
Expected Result:
There should be less than 5 ohms resistance for each measurement.
Results:
- OK - The CAT Data Link circuit in the machine harness is correct.
Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this diagnostic code procedure again. If the cause of the problem is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
Stop.
- NOT OK - There is an open in the harness.
Repair: The open is in wire (945-BR) or wire (944-OR) of the CAT Data Link. Repair the harness or replace the harness.
Stop.