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| Illustration 1 | g01341542 |
Power to the Cat Monitoring System can fail due to an open circuit in the wire, or a blown fuse. A fuse is blown out as a result of an overloaded circuit. For example, the +battery connection is shorted to ground.
Test Step 1. CHECK THE CIRCUIT BREAKER
The open circuit breaker will disrupt power to the Power Train ECM.
The key start switch is in the OFF position.
- Check for an open at the 10 amp circuit breaker.
Expected Result:
The 10 amp circuit breaker is open.
Results:
- YES - The circuit breaker is open.
Repair: Reset the open circuit breaker. Resume machine operation.
STOP
- NO - The 10 amp circuit breaker is not open. Proceed to Test Step 3.
Test Step 2. CHECK THE FUSE
- Disconnect the 10 amp Power Train ECM Master Fuse from the fuse panel.
- Check the resistance across the two fuse contacts.
Expected Result:
The resistance measurement is less than 1.0 ohm.
Results:
- OK - The resistance measurement is less than 1.0 ohm. The fuse is not open. Proceed to Test Step 3.
- NOT OK - The resistance measurement is greater than 1.0 ohms. The fuse is open.
Repair: Replace the fuse with another 10 amp fuse.
STOP
Test Step 3. CHECK THE POWER SUPPLY AT THE ECM
This step requires the use of a 7X-1710 Probe group or similar tool in order to enable voltage measurement at the ECM connector without disconnecting it.
The key start switch is in the OFF position.
- At machine harness connector J1 for the Power Train ECM, insert multimeter probes along supply contact J1-1 (wire 164-WH) and along ground contact J1-2 (wire A273-BK). Measure the DC voltage.
- Repeat the last step for each of the ECM supply contacts and each of the ECM ground contacts that are shown in the illustration at the beginning of this procedure.
Expected Result:
Each voltage measurement measures between 18.0 and 32 VDC.
Results:
- OK - Each voltage measurement measures between 18.0 and 32 VDC. The voltage supply is correct. Proceed to Test Step 4.
- NOT OK - One or more of the voltage measurements is less than 18.0 VDC. There is an open or a bad connection in the machine harness.
Repair: The machine harness is faulty. There is an open or a bad connection in the machine harness for either the power supply circuit wire 164-WH or a ground wire A273-BK.Refer to the complete machine Electrical System Schematic. Check all of the connectors that are in the suspect power or ground circuit. Ensure that all connections are clean, secure and in good condition. Repair the machine harness or replace the machine harness.
STOP
Test Step 4. CHECK THE STATUS OF THE ECM
- Inspect the harness connectors and clean the contacts of the harness connectors in the power supply circuit. Check the wires for damage to the insulation. Verify that each connector contact is clean, secure and in good condition.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the power supply circuit.
- Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are completely fastened.
- Turn key start switch to the ON position.
- Check the status of the ECM.
Expected Result:
The Power Train ECM is performing normally.
Results:
- OK - The Power Train ECM is performing normally. The diagnostic codes that were active are no longer active.
Repair: The problem was probably caused by a poor electrical connection at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.
STOP
- NOT OK - The Power Train ECM is not performing normally. The ECM is still not powered.
Repair: Check the power supply circuit again.If the cause of the problem is not found, the ECM may have failed.It is unlikely that the ECM has failed. Verify that all possible causes of the diagnostic code have been investigated. If the cause of the failure is not found, contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP