16M3 and 18M3 Motor Graders Information Display Caterpillar

Sensor Supply - Test

Usage:

18M3 E9W

Graphical Display

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Table 1
Graphical Display (MID 053)
DTC	Description	System Response
3330-03	Medium Range Object Detection Sensor #2: Voltage Above Normal	Sensors powered by the 12 VDC supply will not function properly. The acceptable range for the 12 VDC power supply is 11.4 VDC to 12.6 VDC.
3330-04	Medium Range Object Detection Sensor #2: Voltage Below Normal	Sensors powered by the 12 VDC supply will not function properly. The acceptable range for the 12 VDC power supply is 11.4 VDC to 12.6 VDC.
3331-03	Medium Range Object Detection Sensor #3: Voltage Above Normal	Sensors powered by the 12 VDC supply will not function properly. The acceptable range for the 12 VDC power supply is 11.4 VDC to 12.6 VDC.
3331-04	Medium Range Object Detection Sensor #3: Voltage Below Normal	Sensors powered by the 12 VDC supply will not function properly. The acceptable range for the 12 VDC power supply is 11.4 VDC to 12.6 VDC.

Root Causes and Schematics

The diagnostic code is recorded when the interface module indicates that the voltage of the sensor supply circuit is too high, too low, or erratic.

Possible causes of an FMI 03 Diagnostic code are:

The output of the sensor supply has shorted to the + battery circuit.
The ECM has failed. The ECM failing is unlikely.

Possible causes of an FMI 04 Diagnostic code are:

The output of sensor supply has an open circuit.
A sensor has failed.
The ECM has failed. This situation is unlikely.

Before performing this procedure, verify that all circuit breakers and all fuses in the charging circuit and the ECM system supply circuit are closed. If a problem with a circuit breaker or a fuse is found, correct the problem, and check for codes before proceeding with the following steps.

Poor harness connections are often the cause of a problem in electrical circuits. Before performing this procedure, inspect all the connectors involved in the circuit. Verify that all the connections in the circuit are dry, clean, secure, and in good condition. Each pin and socket in the connectors should mate correctly when the connectors are fastened together. Check for exposed wires at the connectors for nicks or abrasion. If a problem is found with any of the connections: correct the problem and verify that diagnostic code is still active, before performing the following procedures.

Perform a wiggle test on the sensor circuit of the machine wiring harness, using Cat^® Electronic Technician (Cat ET) Service Tool. The wiggle test can be used to detect open or shorted connections in the machine wiring harness. Reconnect all harness connectors. Make sure that the connectors are fully seated. Observe that the clips for each connector are fastened.

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Illustration 1	g03874899

The preceding diagram is a simplified schematic of the RADAR Sensor power supply connections. The schematic is electrically correct, however, not all the possible harness connectors are shown. Refer to the latest revision of the electrical schematic to view the entire circuitry of the machine.

Diagnostic Trouble Code Procedure

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Table 2
Troubleshooting Test Steps	Values	Results
1. Identify The Active FMI Code Associated With The Sensor Supply Circuit	Code present	FMI 03 diagnostic code, proceed to Test Step 2. FMI 04 diagnostic code, proceed to Test Step 5.
Begin Process For FMI 03 Troubleshooting HERE
2. Check The Sensor Supply Voltage At The Sensors A. Turn the key start switch and the disconnect switch ON. B. Disconnect the machine harness connector from the sensors. C. At the machine harness connector for the sensors, measure the voltage between the voltage supply contact and the voltage return contact.	Voltage is 12.0 VDC ± 0.6 VDC.	OK - The voltage is appropriate for the circuit as determined by the schematic. Verify that the diagnostic code is present. If the code is still active, go to Test Step 4. NOT OK - The reading is NOT the appropriate voltage as determined by the schematic. The voltage is greater than the expected voltage for the circuit based on the schematic. The sensor supply voltage is NOT correct. Proceed to Test Step 3.
3. Check For A Short Circuit In The Machine Harness A. Turn the key start switch and the disconnect switch OFF. B. Disconnect the machine harness connectors from the ECM. C. Disconnect the sensors from the machine harness. D. Measure the resistance from the voltage supply wire to all other contacts in the harness.	The resistance is greater than 5K Ω.	OK - Each resistance measurement is greater than 5K Ω. The ground circuit is correct. Proceed to Test Step 4. NOT OK - One or more of the resistance measurements is less than 5 Ω. There is a short circuit. The supply wire is shorted to whichever resistance measurement was low. Repair: Repair or replace the machine harness. Confirm that the harness repair or replacement has corrected the problem. If the diagnostic code is present after harness repair or replacement, replacement of the ECM may be necessary. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. Review the diagnostic code list in Cat ET and compare the wire connection points on the schematic. Review the schematic for shared sensor connections associated with multiple sensor failures when searching for suspect connections. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit.
4. Check The Voltage At The ECM A. Turn the key start switch and the battery disconnect switch to the OFF position. B. Connect the harness connectors to the ECM. C. At the machine harness connector for the ECM, insert a 7X-1710 Multimeter Probe along the contact for the sensor power. Insert another probe along the return contact for the sensor power. D. Turn the disconnect switch and key start switch to the ON position. E. Observe the voltage output on the multimeter. F. Perform a wiggle test. Gently pull on the wires and move the wires around, at the ECM. Perform the wiggle test at other locations along the wiring harness where connections exist. Perform the wiggle test where damage to the wire casing is obvious. Observe the voltage measurement on the multimeter as machine harness connectors are manipulated.	Voltage is 12.0 VDC ± 0.6 VDC.	OK - The voltage is appropriate for the circuit as determined by the schematic. Proceed to Test Step 8. NOT OK - The voltage measurement is unstable during the wiggle test. The voltage measurement is showing a large amount of variation. The manipulation of the machine harness and connectors affects the measurement. Repair- Repair, if possible, or replace the wiring harness. The wiggle test has revealed a possible short circuit or grounded circuit. Inspect the wiring harness for damage. Inspect the harness connectors for corrosion or loose connections. Use the information gathered from the wiggle test to identify the faulty wire connection. After completing the repair, perform a wiggle test to confirm the repair. STOP NOT OK - The voltage measurement is stable but not within the specified range. Confirm that the voltage source is not contacting another voltage source or ground source. After completing all multimeter measurements, the ECM may require replacement. Prior to replacing an ECM consult with the Technical Communicator at your dealership for possible consultation with Caterpillar. STOP.
Begin Process For FMI 04 Troubleshooting HERE
5. Check The Sensors A. Turn key start switch and disconnect switch ON. B. One at a time, disconnect the sensors from the machine harness. C. After disconnecting each sensor, check the status of the diagnostic code.	The diagnostic code is no longer active.	OK - The diagnostic code is not active when one of the sensors is disconnected. The harness circuit is correct. The sensor that was most recently disconnected has failed. Repair - Replace the sensor in question. Verify that the new sensor has corrected the problem. NOT OK- The diagnostic code remained active. Proceed to Test Step 6.
6. Check The Supply Voltage At The Sensors A. Turn the key start switch and the disconnect switch ON. B. Use the machine schematic to identify each sensor supplied by the suspect voltage source. C. One at a time, disconnect the machine harness connector from each of the sensors in the circuit. D. At the machine harness connector for each sensor, measure the voltage between the voltage supply contact and the voltage return contact.	Voltage is 12.0 VDC ± 0.6 VDC.	OK - The voltage is appropriate for connections of the circuit as determined by the schematic. Verify that the diagnostic code is present. If the code is still active, go to Test Step 8. Proceed to Test Step 8. NOT OK - The reading is NOT the appropriate voltage as determined by the schematic. The voltage is greater than the expected voltage for the circuit based on the schematic. The sensor supply voltage is below the expected level for one or more of the sensors. Confirm that the harness connectors for the suspect sensors are secure and the connections are clean. Proceed to Test Step 7.
7. Check For A Short Circuit In The Machine Harness A. Turn the key start switch and the disconnect switch OFF. B. Disconnect the sensors from the machine harness one at a time. Disconnect the machine harness connectors from the ECM. C. Measure the resistance from the voltage supply wire to all other contacts in the harness.	The resistance readings are greater than 5K Ω.	OK - The resistance is greater than 5K Ω. The harness circuit resistance is correct. Proceed to Test Step 8. NOT OK - Resistance is less than 5 Ω. The supply wire is shorted at the pins where the resistance measurement was low. Repair: Repair or replace the machine harness. Confirm that the harness repair or replacement has corrected the problem. Note: A resistance that is greater than 5 Ω but less than 5K Ω indicates a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit.
8. Check If The Diagnostic Code Remains A. Turn the key start switch and the disconnect switch ON. B. Clear all diagnostic codes. C. Operate the machine. D. Stop the machine and engage the parking brake. E. Check if diagnostic code is active.	Code for supply voltage is NO longer present.	OK - No active diagnostic code. The problem does not exist at this time. The initial diagnostic code may have been caused by a poor or intermittent electrical connection. Resume normal machine operation. NOT OK - Perform this procedure again. Verify that the measurements for the alternator are correct. Verify that the system voltage circuit connections are in good condition and verify that the system voltage circuit connections are tight. Repair- If the problem remains and no cause can be found, the ECM may have failed. A failed ECM is unlikely. Prior to replacing the ECM, contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. STOP.