140 Motor Grader Electrical Troubleshooting Caterpillar

Sensor Signal (Analog, Passive) - Test

Usage:

140 N94

Transmission/Chassis ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the analog passive sensors of the machine.

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Table 1
Transmission/Chassis ECM (MID 027)
J1939	CDL	Code Description	System Response
	96-3	Fuel Level Sensor: Voltage Above Normal	A Warning Level 1 Will Be Generated.
	96-4	Fuel Level Sensor: Voltage Below Normal	A Warning Level 1 Will Be Generated.
	177-3	Transmission Oil Temperature Sensor: Voltage Above Normal	A Warning Level 1 Will Be Generated.
	177-4	Transmission Oil Temperature Sensor: Voltage Below Normal	A Warning Level 1 Will Be Generated.
	600-3	Hydraulic Oil Temperature Sensor: Voltage Above Normal	A Warning Level 1 Will Be Generated.
	600-4	Hydraulic Oil Temperature Sensor: Voltage Below Normal	A Warning Level 1 Will Be Generated.
	4007-3	Air Conditioner #1 Evaporator Temperature Sensor: Voltage Above Normal	A Warning Level 1 Will Be Generated.
	4007-4	Air Conditioner #1 Evaporator Temperature Sensor: Voltage Below Normal	A Warning Level 1 Will Be Generated.

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Illustration 1	g06373152
Schematic of analog passive circuits for Transmission/Chassis ECM

Note: The diagram above is a simplified schematic of the Transmission/Chassis ECM and the Passive Analog connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, M0098753 for the complete schematic.

AWD ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the analog passive sensors of the machine.

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Table 2
AWD ECM (MID 075)
J1939	CDL	Code Description	System Response
	600-3	Hydraulic Oil Temperature Sensor: Voltage Above Normal	A Warning Level 1 Will Be Generated.
	600-4	Hydraulic Oil Temperature Sensor: Voltage Below Normal	A Warning Level 1 Will Be Generated.

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Illustration 2	g06373165
Schematic of analog passive circuit for the AWD ECM.

Note: The diagram above is a simplified schematic of the Implement ECM and the Passive Analog connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, M0098753 for the complete schematic.

Diagnostic Trouble Code Procedure

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Table 3
Required Tools
Tool	Part Number	Description	Qty
T1	146-4080⁽¹⁾	Digital Multimeter Group	1
	8T-3224	Needle Tip Group	1
	7X-1710	Multimeter Probe Group	1
	8T-8726	Cable Assembly (Three Pin) (3-Pin Breakout)	1
T2	JERD2129	Cat^® Electronic Technician (Cat ET)	1
		Windows-based PC	1
	466-6258	Communication Adapter Gp	1
T3	6V-4148	Connector Repair Kit (Sure Seal)	1
T4	190-8900	Connector Field Repair Kit (Deutsch)	1
T5	175-3700	Connector Repair Kit Deutsch DT	1

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⁽¹⁾	This multimeter can use an RS232C cable to connect to a Laptop computer or Dataview tool gp for troubleshooting.

Prior to beginning this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure and in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.

Identify the active FMI code associated with the components.
Determine which code is present and use the list below to determine which procedure to follow.

FMI 3 diagnostic code, proceed to "FMI 3".
FMI 4 diagnostic code, proceed to "FMI 4".

FMI 3

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Table 4
Check The Sensor
Troubleshooting Test Steps	Values	Results
Note: Refer to the tables above for a list of resistance values related to specific values. 1. Turn the key start switch and the disconnect switch to the OFF position. 2. Disconnect the sensor from the harness. 3. Measure the resistance between pin 1 and 2 of the sensor.	The resistance reading agrees with the values from the table.	Result: The resistance readings agree with the values in the table. Proceed to "Check For An Open In The Sensor Circuit", Table 5. Result: The resistance readings do not agree with the values in the table. Repair: Replace the sensor. Proceed to "Check If The Diagnostic Code Remains", Table 7.

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Table 5
Check For An Open In The Sensor Circuit
Troubleshooting Test Steps	Values	Results
1. The key start switch and disconnect switch remain in the OFF position. 2. The harness connector remains disconnected from the sensor. 3. At the sensor harness connector, install a jumper wire across pins 1 and 2. 4. Disconnect the J1 and J2 connectors from the ECM. 5. At the ECM harness connector, measure the resistance between the signal and return contacts for the sensor.	The resistance reading is less than 5 Ω.	Result: The resistance is less than 5 Ω. Proceed to "Check The Signal Circuit For A Short", Table 6. Result: The resistance is greater than 5 Ω. The open is in the signal circuit or the return circuit. Repair: Repair or replace the harness. Proceed to "Check If The Diagnostic Code Remains", Table 7.

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Table 6
Check The Signal Circuit For A Short
Troubleshooting Test Steps	Values	Results
1. The disconnect switch and the key start switch remain in the OFF position. 2. The harness connectors J1 and J2 remain disconnected from the ECM. 3. Remove the jumper wire from the sensor harness connector. 4. At the ECM harness connectors, measure the resistance between the signal circuit and all the other contacts that are used on the ECM.	Each resistance reading is greater than 5K Ω.	Result: Each measurement is greater than 5K Ω. Proceed to "Check If The Diagnostic Code Remains", Table 7. Result: A resistance measurement is less than 5 Ω. A short exists between the signal circuit and the circuit with the low-resistance measurement. Repair: Repair or replace the machine harness. Proceed to "Check If The Diagnostic Code Remains", Table 7.

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Table 7
Check If The Diagnostic Code Remains
Troubleshooting Test Steps	Values	Results
1. Reconnect all harness connectors. Return machine to normal operating condition. 2. Turn the key start switch and the disconnect switch ON. 3. Clear all diagnostic codes. 4. Operate the machine. 5. Stop the machine and engage the safety lock lever. 6. Check if the diagnostic code is active.	The diagnostic code is no longer present.	Result: The diagnostic code does not exist currently. The initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation. STOP. Result: The diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement. Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time. Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced. STOP.

FMI 4

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Table 8
Check The Sensor
Troubleshooting Test Steps	Values	Results
1. Turn the key start switch and disconnect switch ON. 2. Ensure that the diagnostic code is active. 3. Disconnect sensor from machine harness.	The diagnostic code remains active.	Result: Diagnostic code remains active. Proceed to "Check The Wiring Harness Of The Sensor For A Short To Ground", Table 9. Result: Diagnostic code is no longer active. Repair: Replace the sensor. Proceed to "Check If The Diagnostic Code Remains", Table 10.

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Table 9
Check The Wiring Harness Of The Sensor For A Short To Ground
Troubleshooting Test Steps	Values	Results
1. Turn the key start switch and the disconnect switch OFF. 2. Disconnect the machine harness connector from the sensor. 3. Disconnect the machine harness connectors from the ECM. 4. At the ECM harness connectors, measure the resistance between the signal circuit and all the other contacts that are used on the ECM.	Each reading greater than 5K Ω.	Result: All resistance readings are greater than 5K Ω. Proceed to "Check If The Diagnostic Code Remains", Table 10. Result: One or more of the readings are less than 5 Ω. A short exists between the signal contact and the circuit with the low resistance. Repair: Repair or replace the machine harness. 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. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to "Check If The Diagnostic Code Remains", Table 10.

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Table 10
Check If The Diagnostic Code Remains
Troubleshooting Test Steps	Values	Results
1. Reconnect all harness connectors. Return machine to normal operating condition. 2. Turn the key start switch and the disconnect switch ON. 3. Clear all diagnostic codes. 4. Operate the machine. 5. Stop the machine and engage the safety lock lever. 6. Check if the diagnostic code is active.	The diagnostic code is no longer present.	Result: The diagnostic code does not exist currently. The initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation. STOP. Result: The diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement. Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time. Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced. STOP.