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| Illustration 1 | g02346939 |
Schematic of the main E/H pump pressure sensor | |
The CID 2828 diagnostic code is associated with the main hydraulic pump pressure sensor. The sensor produces an analog signal. The signal wire (N931-GY) connects to contact J1-36 of the Implement ECM 2. The FMI 03 is recorded when the Implement ECM 2 reads the signal from the pressure sensor (wire N931-GY) as being shorted to the + battery.
Possible causes of the diagnostic code are listed below:
- The supply circuit (wire 997-OR) to the sensor is open.
- The return circuit (wire 998-BR) is open.
- The signal circuit (wire N931-GY) is shorted high.
- The signal circuit is open or the sensor is disconnected.
- The sensor has failed.
- The ECM has failed. This condition is unlikely.
Note: Ensure that the CID 02828 FMI 03 diagnostic code is active. This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. When the procedure is completed, clear the created diagnostic codes.
Test Step 1. CHECK THE VOLTAGE AT THE SENSOR
- Turn the disconnect switch and the key start switch to the ON position.
- Disconnect the sensor from the machine harness.
- At the machine harness connector for the sensor, measure the voltage between contact A (wire 997-OR) and contact B (wire 998-BR).
Expected Result:
The voltage measurement is approximately 5 VDC.
Results:
- OK - The voltage measurement is approximately 5 VDC. Proceed to test step 4.
- NOT OK - The voltage is not approximately 5 VDC. There is an open in the machine harness or the ECM has failed. The failed condition of the ECM is unlikely. Proceed to test step 2.
Test Step 2. CHECK FOR AN OPEN IN THE SUPPLY CIRCUIT
- The key start switch and the disconnect switch remain in the ON position.
- The sensor remains disconnected from the machine harness.
- At the machine harness connector for the sensor, measure the voltage from contact A (wire 997-OR) to ground.
Expected Result:
The voltage measurement is approximately 5 VDC.
Results:
- OK - The voltage measurement is approximately 5 VDC. Proceed to test step 3.
- NOT OK - The voltage does not measure approximately 5 VDC. The supply circuit is not correct.
Repair: Repair the circuit or replace the circuit.
STOP
Test Step 3. CHECK FOR AN OPEN IN THE RETURN CIRCUIT.
- Turn the key start switch and the disconnect switch to the OFF position.
- The sensor remains disconnected from the machine harness.
- Disconnect the machine harness connector J1 from the Implement ECM.
- At the machine harness connector for the sensor, install a jumper wire from contact B (wire 998-BR) to ground.
- At the machine harness connector for the Implement ECM, measure the resistance from contact J1-21 (wire 998-BR) to ground.
Expected Result:
The resistance measurement is less than 5.0 ohms.
Results:
- OK - The resistance measurement is less than 5.0 ohms. The harness is correct. The Implement ECM 2 may have failed.
Repair: The failed condition of the ECM is unlikely. Recheck the status of the diagnostic code. If the diagnostic code remains present, exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. Contact the Technical Communicator for your dealership for possible consultation with Caterpillar. prior to replacing the ECM. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Troubleshooting, "Electronic Control Module (ECM) - Replace".
STOP
- NOT OK - The resistance measurement is greater than 5.0 ohms. There is an open in the return circuit with the high resistance measurement
Repair: Repair the harness or replace the harness.
STOP
Test Step 4. CHECK FOR AN OPEN IN THE SIGNAL CIRCUIT
- Turn the key start switch and the disconnect switch to the OFF position.
- Disconnect the J1 machine harness connector from the Implement ECM 2.
- At the machine harness connector for the sensor, install a jumper wire from contact C (wire N931-GY) to contact B (wire 998-BR).
- At the machine harness connector J1, measure the resistance from contact J1-36 (wire N931-GY) to contact J1-21 (wire 998-BR).
Expected Result:
The resistance measurement is less than 5.0 ohms.
Results:
- OK - The resistance measurement is less than 5.0 ohms. Proceed to 5.
- NOT OK - The resistance measurement is greater than 5.0 ohms. There is an open in the signal circuit.
Repair: Repair the harness or replace the harness.
STOP
Test Step 5. CHECK THE SIGNAL CIRCUIT FOR A SHORT
- The disconnect switch and the key start switch remain in the OFF position.
- The machine harness connector J1 remains disconnected.
- Remove the jumper wire from contact C (wire N931-GY) to contact B (wire 998-BR).
- Disconnect the machine harness connector J2 from the Implement ECM 2.
- At the J1 and J2 machine harness connectors for the Implement ECM 2, measure the resistance for the signal contact of the sensor J1-36 (wire N931-GY) to all other J1 and J2 contacts.
Expected Result:
Each resistance is greater than 5000 ohms.
Results:
- OK - Each resistance measurement is greater than 5000 ohms. The sensor has failed.
Repair: Replace the sensor.Verify that the new sensor corrected the problem. If the problem persists, The ECM may have failed.The failed condition of the ECM is unlikely. Recheck the status of the diagnostic code. If the diagnostic code remains present, exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. Contact the Technical Communicator for your dealership for possible consultation with Caterpillar. prior to replacing the ECM. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Troubleshooting, "Electronic Control Module (ECM) - Replace".
STOP
- NOT OK - The resistance measures less than 5000 ohms. There is a short between the signal circuit and the circuit with the low resistance measurement.
Repair: Repair the harness or replace the harness.
Proceed to Test Step 6
Test Step 6. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Inspect the harness connectors. Clean the contacts of the harness connectors. Check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.
- Reconnect all harness connectors. Make sure that the connectors are fully seated. Observe that the clips for each connector are fastened completely.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 2829 FMI 14 diagnostic code is active.
Expected Result:
The CID 2829 FMI 14 diagnostic code is not active.
Results:
- OK - The CID 2829 FMI 14 diagnostic code is not active. The problem has been corrected.
Repair: The initial diagnostic code was probably caused by a poor electrical connection that was resolved when a harness connector was disconnected and reconnected. Resume normal machine operation.
STOP
- NOT OK - The CID 2829 FMI 14 diagnostic code is still active. The problem has not been corrected.
Repair: Perform this test step again. If the problem has not been corrected, proceed with the following process. Use a Caterpillar Electronic Technician service tool and perform a wiggle test on the sensor circuit for the machine wiring harness of the machine. The wiggle test can be used to detect momentary short circuit connections. The wiggle test can also be used to detect open connections in the machine wiring harness.If a problem is not found in the machine harness, replace the pressure sensor. If the problem is still present after replacement of the sensor, the Implement ECM 2 may have failed.Prior to replacing an ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the cause of the diagnostic code is not found, replace the Implement ECM. Refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP