D7 Track-Type Tractor Electrohydraulic Systems Sensor Signal (Analog, Passive) - Test Caterpillar


Sensor Signal (Analog, Passive) - Test
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1.1. Implement ECM
2.1. Machine ECM
3.1. Diagnostic Trouble Code Procedure
4.1. FMI 3
5.1. FMI 4

Implement ECM

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

Table 1
Implement ECM (MID 82) 
J1939  CDL  Code Description  System Response 
  600-3  Hydraulic Oil Temperature Sensor: Voltage Above Normal  Hydraulic Oil temperature Sensor does not function properly.
Hydraulic Filter Bypass may not activate.
Events related to high temperature will not be triggered by the ECM
Some calibrations and service tests cannot be initiated. 
  600-4  Hydraulic Oil Temperature Sensor: Voltage Below Normal  Hydraulic Oil temperature Sensor does not function properly.
Hydraulic Filter Bypass may not activate.
Events related to high temperature will not be triggered by the ECM
Some calibrations and service tests cannot be initiated. 
  779-3  Cab Air Temperature Sensor: Voltage Above Normal  The Auto Temperature Control feature is disabled. 
  779-4  Cab Air Temperature Sensor: Voltage Below Normal  The Auto Temperature Control feature is disabled. 
  2357-3  Air Conditioner Evaporator Coil Temperature Sensor: Voltage Above Normal  The Auto Temperature Control feature will not work properly. Stand alone AC operation may also not work properly. 
  2357-4  Air Conditioner Evaporator Coil Temperature Sensor: Voltage Below Normal  The Auto Temperature Control feature will not work properly. Stand alone AC operation may also not work properly. 
  2663-3  Cab Ventilation Duct Temperature Sensor: Voltage Above Normal  The Auto Temperature Control feature is disabled. 
  2663-4  Cab Ventilation Duct Temperature Sensor: Voltage Below Normal  The Auto Temperature Control feature is disabled. 

A passive analog sensor contains an internal resistor. The change in resistance of the internal circuit results in a change of voltage that is detected by the electronic control module.



Illustration 1g06497677
Passive analog sensor connections

The preceding diagram is a simplified schematic of the connections for the passive analog sensors. The schematic is electrically correct. However, not all the possible harness connectors are shown. Refer to the latest revision of the electrical schematic for the specific machine being serviced for the complete schematic.

Table 2
Temperature Range ( 256-6453) 
C° Temperature  F° Temperature  Resistance 
-40  -40  33650.2 
32  3268.3 
25  77  1000 
50  122  360 
100  212  68 
150  302  18.6 

Machine ECM

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

Table 3
Machine ECM (MID 39) 
J1939  CDL  Code Description  System Response 
  177-3  Transmission Oil Temperature Sensor: Voltage Above Normal  The ECM will not be able to read the transmission oil temperature.
If the transmission oil is cold, harsh transmission shifts will occur. 
  177-4  Transmission Oil Temperature Sensor: Voltage Below Normal  The ECM will not be able to read the transmission oil temperature.
If the transmission oil is cold, harsh transmission shifts will occur. 
  826-3  Torque Converter Oil Temperature Sensor: Voltage Above Normal  The ECM will not be able read the torque converter temperature.
If the oil temperature is too hot, the ECM will not activate the high oil temperature event.
If the machine is operated, damage to Torque Converter components will occur. 
  826-4  Torque Converter Oil Temperature Sensor: Voltage Below Normal  The ECM will not be able read the torque converter temperature.
If the oil temperature is too hot, the ECM will not activate the high oil temperature event.
If the machine is operated, damage to Torque Converter components will occur. 
  3657-3  Operator In Seat Sensor: Voltage Above Normal  Machine operation will be inhibited while the machine is stationary. 
  3657-4  Operator In Seat Sensor: Voltage Below Normal  Machine operation will be inhibited while the machine is stationary. 


Illustration 2g06477011
Schematic of the passive analog sensors

The preceding diagram is a simplified schematic of the connections for the passive analog sensors. The schematic is electrically correct. However, not all the possible harness connectors are shown. Refer to the latest revision of the electrical schematic for the specific machine being serviced for the complete schematic.

Diagnostic Trouble Code Procedure

Table 4
Required Tools 
Tool  Part Number  Description  Qty 
T1  146-4080(1)  Digital Multimeter Group 
8T-3224 Needle Tip Group 
7X-1710 Multimeter Probe Group 
8T-8726 Cable Assembly (Three Pin) (3-Pin Breakout) 
T2  JERD2129  Cat® Electronic Technician (Cat ET) 
Windows-based PC 
538-5051 Communication Adapter Gp 
T3  6V-4148  Connector Repair Kit (Sure Seal) 
T4  190-8900  Connector Field Repair Kit (Deutsch) 
T5  175-3700  Connector Repair Kit Deutsch DT 
(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 this 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. Check the wiring for pinch points or abrasions. Look for and repair areas that indicate wires are exposed. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing a troubleshooting procedure.

  1. Identify the active FMI code associated with the components.

  2. 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

Table 5
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 6.

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 8. 

Table 6
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 7.

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 8. 

Table 7
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 8.

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 8. 

Table 8
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 AVSpare. This consultation may effect repair time.

For more information refer to the "ECM - Replace" section if the ECM needs to be replaced.

STOP

FMI 4

Table 9
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 10.

Result: Diagnostic code is no longer active.

Repair: Replace the sensor.

Proceed to "Check If The Diagnostic Code Remains", Table 11. 

Table 10
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 11.

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 11. 

Table 11
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 AVSpare. This consultation may effect repair time.

For more information refer to the "ECM - Replace" section if the ECM needs to be replaced.

STOP

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