844K Wheel Dozer Caterpillar


CAN Data Link - Test

Usage:

844K K4Y

Transmission ECM

This Data Link is used for communication between most ECM modules on the machine. Commonly this data link is used for communication between the Engine Control Module, the Machine Control Module, and other applicable modules (depending on the machine configuration).

The following is a list of Diagnostic Trouble codes (DTC) that are associated with the CAN A Data Link and CAN B Data Link for the Transmission ECM.

Table 1
Transmission ECM (MID 81) 
DTC  Code Description  System Response 
590-9  Engine Control Module: Abnormal Update Rate  This failure results in events that are logged against the Transmission ECM that cannot be explained directly. The Transmission ECM cannot communicate with the Engine ECM or appears to communicate intermittently. 
590-14  Engine Control Module: Special Instruction  Software will run in a generic state and all software features related to the machine control are disabled. 
596-9  Implement Control Module: Abnormal Update Rate  This failure results in events that are logged against the Transmission ECM that cannot be explained directly. The Transmission ECM cannot communicate with the Implement ECM or appears to communicate intermittently. 
596-14  Implement Control Module: Special Instruction  Software will run in a generic state and all software features related to the machine control are disabled. 
871-9  Inclination Sensor: Abnormal Update Rate  This failure results in events that are logged against the Transmission ECM that cannot be explained directly. The Transmission ECM cannot communicate with the inclination sensor or appears to communicate intermittently. 
967-9  Machine Application: Abnormal Update  Software will run in a generic state and all software features related to the machine control are disabled. 
967-14  Machine Application: Special Instruction  Software will run in a generic state and all software features related to the machine control are disabled. 
2448-9  Graphical Display Module : Abnormal Update Rate  This failure results in events that are logged against the Transmission ECM that cannot be explained directly. The Transmission ECM cannot communicate with the display module or appears to communicate intermittently. 
2448-14  Graphical Display Module: Special Instruction  Software will run in a generic state and all software features related to the machine control are disabled. 
3583-9  Switch Panel #1: Abnormal Update Rate  This failure results in events that are logged against the Transmission ECM that cannot be explained directly. The Transmission ECM cannot communicate with the switch panel or appears to communicate intermittently. 

Possible causes for a DTC 967-9 diagnostic Trouble Code are:

  • The Transmission ECM or Implement ECM are operating intermittently.

Possible causes for a DTC 967-14 Diagnostic Trouble Code are:

  • A fuse for one of the ECM modules may have failed.

  • The software is incorrect or incompatible for one of the modules in the data link.

  • The machine harness has failed.

  • One of the ECM modules in the data link has failed.

Possible cause for all other Diagnostic Trouble Codes related to the CAN Data Link are:

  • An open or a poor connection in the CAN Data Link circuit.

  • The energize circuit for the sensor may have failed.

  • The Implement ECM or Transmission ECM has failed. This situation is unlikely.

  • One or both of the resistors in the CAN Data Link circuit has failed.


Illustration 1g03581609
Schematic of the CAN Data Link

Note: The diagram above is a simplified schematic of the data link circuit connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of: Electrical Schematic, UENR4996, "844K Wheel Dozer (T4F) Electrical System Schematic" Electrical Schematic, UENR1697, "844K Wheel Dozer (LRC) Electrical System Schematic"

Implement ECM

This Data Link is used for communication between most ECM modules on the machine. Commonly this data link is used for communication between the Engine Control Module, the Machine Control Module, and other applicable modules (depending on the machine configuration).

The following is a list of Diagnostic Trouble codes (DTC) that are associated with the CAN A Data Link and the CAN B Data Link for the Implement ECM.

Table 2
Implement ECM (MID 82) 
DTC  Code Description  System Response 
296-9  Transmission Control: Abnormal Update Rate  This failure results in events that are logged against the Implement ECM that cannot be explained directly. The Implement ECM cannot communicate with the Transmission ECM or appears to communicate intermittently. 
296-14  Transmission Control: Special Instruction  Software will run in a generic state and all software features related to the machine control are disabled. 
590-9  Engine Control Module: Abnormal Update Rate  This failure results in events that are logged against the Implement ECM that cannot be explained directly. The Implement ECM cannot communicate with the Engine ECM or appears to communicate intermittently. 
590-14  Engine Control Module: Special Instruction  Software will run in a generic state and all software features related to the machine control are disabled. 
967-9  Machine Application: Abnormal Update  This failure results in events that are logged against the Implement ECM that cannot be explained directly. The Implement ECM cannot communicate with the Machine Application Control or appears to communicate intermittently. 
967-14  Machine Application: Special Instruction  Software will run in a generic state and all software features related to the machine control are disabled. 

Possible Causes for a DTC 967-9 Diagnostic Trouble Code are:

  • The Transmission ECM or Implement ECM are operating intermittently.

Possible causes for a DTC 967-14 Diagnostic Trouble Code are:

  • A fuse for one of the ECM modules may have failed.

  • The software is incorrect or incompatible for one of the modules in the data link.

  • The machine harness has failed.

  • One of the ECM modules in the data link has failed.

Possible cause for all other Diagnostic Trouble Codes related to the CAN Data Link are:

  • An open or a poor connection in the CAN Data Link circuit.

  • The energize circuit for the sensor may have failed.

  • The Implement ECM or Transmission ECM has failed. This situation is unlikely.

  • One or both of the resistors in the CAN Data Link circuit has failed.


Illustration 2g03581609
Data Link Schematic detailing the connections between the Transmission ECM and the Implement ECM (DTC - 247-9).


Illustration 3g03581757
Graphic displaying the connections of the CAN A (or CAN 1) Data Link


Illustration 4g03581612
Data Link schematic illustrating the connections between the Transmission ECM and the modules along the CAN B (or CAN 2) Data Link.


Illustration 5g03637417
Graphic displaying the connections of the CAN 2 Data Link

Note: The diagrams above are simplified schematics of the data link circuit connections. The schematics are electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of: Electrical Schematic, UENR4996, "844K Wheel Dozer (T4F) Electrical System Schematic" Electrical Schematic, UENR1697, "844K Wheel Dozer (LRC) Electrical System Schematic"

Diagnostic Trouble Code Procedure

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.

Table 3
Troubleshooting Test Steps  Values  Results 
1. Identify The Active DTC Associated With The CAN Data Link Circuit. 
Code present. 
DTC 871-9, proceed to Test Step 2.

DTC 247-9 , proceed to Test Step 4.

DTC 967-9, proceed to Test Step 8. (1)

DTC 967-14, proceed to Test Step 14. (2)

DTC 3583-9, proceed to Test Step 17. 
Begin Process For DTC 871-9 Troubleshooting HERE 
2. Check For Power To The Inclination Sensor.

A. With the key switch ON, check for system voltage between pin 6 of the Inclination sensor module and ground. 

The voltage measurement is 10 ±0.7 VDC. 
OK - The voltage that is measured is approximately 10 VDC. The voltage is correct.

Proceed to Test Step 4.

NOT OK - Check all harness connectors for loose connections or corrosion, repair as needed. If the problem cannot be identified, Proceed to Test Step 3. 
3. Check The Resistor For The Power Supply Circuit.

A. Turn the key switch and disconnect switch to the OFF position.

B. Identify the F2 location on the fuse panel.

C. Remove the resistor from the fuse location and measure the resistance of the resistor. 

The resistor measures 200 Ω. (Check the tolerance band or notation on the resistor to determine the acceptable tolerance.) 
OK - The measurement of the resistor is correct, allowing for the specified tolerance. Install the resistor at location F2 of the fuse panel.

Proceed to Test Step 4.

NOT OK - The resistor measurement is not correct.

Repair: Replace the resistor.

Turn the disconnect switch and key start switch to the ON position. Clear all diagnostic codes. Operate the machine.

If the diagnostic code 871-9 remains active, proceed to Test Step 4. 
Begin Process For DTC 247-9 Troubleshooting HERE 
4. Check The Data Link Circuit For An Open

Two CAN data link resistors are connected in parallel to each CAN data link circuit. Each resistor is a 120 Ω resistor. When a resistance measurement is taken between the data link circuits, the resistance will be approximately 60 Ω.

A. Turn key start switch and disconnect switch OFF.

B. Refer to Illustration 4. Disconnect the machine harness connectors, CAN Data Link connections from each component in the system. Leave the CAN Data Link resistors connected to the system.

C. Inspect each machine harness connector of the CAN data link circuit for signs of dirty, loose, or corroded connector pins. Ensure that all CAN data link connections are secured in the connector, the contacts are clean, and the contacts are in good condition.

D. At the disconnected harness connector for the suspected module, connect a jumper wire between the contacts for the CAN Data Link circuit.

E. Measure the resistance between the CAN Data Link contacts. 

The circuit reading is around 60 Ω. 
OK - The CAN data link circuit is correct.

Proceed to Test Step 5.

NOT OK - The resistance measured is approximately 120 Ω.

Repair: Refer to the full electrical schematic and remove each of the data link resistors for the suspected circuit. Remove the resistor from the circuit. Measure the resistance of each resistor (at pins A and B). Replace the resistor that is not within the acceptable range of 120 Ω.

NOT OK - The resistance measured is greater than 120 Ω.

Repair: There is an open or a bad connection in the CAN Data Link circuit in the machine harness. Repair or replace the machine harness.

Note: A resistance greater than 120 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.

STOP 
5. Check The CAN Data Link Wiring Of The Machine Harness For A Short To Ground.

A. Disconnect the J2 wiring harness connector for the Transmission ECM or the Implement ECM.

Note: The ECM that is disconnected for this step depends on the diagnostic code being investigated.

B. Measure the resistance between the positive pin of the suspected CAN data link at the ECM harness connector and frame ground. 

Resistance is greater than 5K Ω. 
OK - The resistance is greater than 5K Ω. The resistance is correct.

Proceed to Test Step 6.

NOT OK - The resistance is less than 5 Ω. The wiring harness is shorted to ground.

Repair: Check the wiring harness for signs of damage. 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.

STOP 
6. Check The CAN Data Link Wiring Of The Machine Harness For A Short To +Battery

A. The J2 wiring harness connector for the ECM remains disconnected.

B. Measure the resistance between the positive pin of the CAN Data Link at the ECM harness connector and +battery. 

Resistance is greater than 5K Ω. 
OK - The resistance is greater than 5K Ω. The resistance is correct.

Proceed to Test Step 7.

NOT OK - The resistance is less than 5 Ω. The wiring harness is shorted to the +battery circuit.

Repair: Check the wiring harness for signs of damage. Repair or replace the machine harness.

Note: A resistance that is greater than 5 ohms 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.

STOP 
7. Check The CAN Data Link Termination Resistors For An Open Circuit

A. Locate and remove each CAN Data Link termination resistor.

B. Measure the resistance between pin A and pin B on both resistor plugs. 

Each resistance measures approx. 120 Ω. 
OK - The resistance is approximately 120 Ω on each resistor plug. The resistance is correct. Reinstall the termination resistor plugs.

Repair: The Implement ECM has failed. If the cause of the problem is not found, replace the ECM module and test again. If the cause of the problem is still not found, replace the Transmission ECM. A failure of the Transmission ECM is unlikely.

Prior to replacing an ECM, contact the Technical Communicator for your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time.

Refer to the Troubleshooting, "ECM - Replace" section of this manual for additional information.

STOP

NOT OK - The resistance is greater than 120 ohms for one or both of the resistor plugs.

Repair: Replace the faulty termination resistor.

STOP 
Begin Process For DTC 967-9 Troubleshooting HERE 
8. Verify The Hardware And The Software Part Numbers(3)

A. The part number of the flash software for the suspect ECM.

B. The part number of the flash software for the "Monitor Display" ECM.

C. The part number of all components related to the faulty Data Link Circuit. 

All part numbers are correct. 
OK - All part numbers are correct.

Proceed to Test Step 9.

NOT OK - All of the part numbers are not correct.

Repair: A module has the wrong part number or the incorrect flash software is installed. Replace the incorrect module with a module that has the correct part number. Flash the correct software. See the Troubleshooting, "ECM Software - Install" section of this manual for additional information.

STOP 
9. Inspect The Harness Connections

A. Turn key start switch and disconnect switch OFF.

B. Inspect all harness connections related to the CAN Data Link. Make sure that the connectors are clean and tight.

C. Check the connectors for proper mating. Ensure that all the seals are present and in place.

D. Check the harness for signs of damage or abrasion.

E. Check the wires at the connector. Ensure that the wires are secured tightly into the connector. Take care not to pull the wire out of the connector.

F. Check the exposed wires at the connectors for nicks or signs of abrasion.

G. Check for moisture inside the connector.

H. Check the connectors for dirty contacts or corroded contacts.

I. Check each pin and each socket of the machine harness connectors. Ensure that the contacts are properly installed. The contacts should mate correctly when the two pieces of the connector are placed together. 

The machine harness connectors are tight and free of corrosion. 
OK - The machine harness connectors are tight and free of corrosion.

Proceed to Test Step 10.

NOT OK - The machine harness connectors are in need of repair.

Repair: Repair or replace the machine harness.

STOP 
10. Check For Shorts To Ground

A. The key start switch and disconnect switch remain OFF.

B. Disconnect the machine harness connectors from all electronic control modules that use the suspect CAN Data Link.

C. At the machine harness for the suspect ECM, measure the resistance between frame ground and the positive CAN connector contact of the circuit.

D. At the machine harness for the suspect ECM, measure the resistance between frame ground and the negative CAN connector contact of the circuit. 

The reading is greater than 5K Ω. 
OK - The harness circuit resistance is correct.

Proceed to Test Step 11.

NOT OK - A reading is less than 5 Ω. The machine harness has failed.

Repair: Short between frame ground and the contacts of the CAN Data Link circuit in the machine harness. 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.

STOP 
11. Check For Shorts To The +Battery Circuit

A. The key start switch and disconnect switch are OFF.

B. All related modules remain disconnected from the machine harness.

C. At the machine harness connector for the suspect ECM, measure the resistance between the connector contact for the +Battery and the positive CAN connector contact.

D. At the machine harness connector for the suspect ECM, measure the resistance between the connector contact for the +Battery and the negative CAN connector contact. 

The reading is greater than 5K Ω. 
OK - The harness circuit resistance is correct.

Proceed to Step 12.

NOT OK - A reading is less than 5 Ω. The machine harness has failed.

Repair: There is a short between the +battery circuit and one of the contact for the CAN Data Link circuit in the machine harness. 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.

STOP 
12. Check For Open Harness

A. The key start switch and disconnect switch are OFF.

B. All related electronic control modules remain disconnected from the machine harness.

C. Check the resistance of the CAN Data Link circuit in the machine harness.

D. Insert a probe at the positive CAN Data Link contact of the suspect ECM.

E. Insert a probe at the positive CAN Data Link contact of another module associated with the circuit.

F. Measure the resistance between the contacts.

G. Repeat process for all modules associated with circuit. 

Reading is less than 5 Ω. 
OK - The CAN Data Link circuit in the machine harness is correct.

Proceed to Step 13.

NOT OK - A reading is greater than 5K Ω. The machine harness has failed.

Repair: The CAN Data Link circuit is open in the machine harness. 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.

STOP 
13. Check For Additional Diagnostic Codes For The Other Electric Control Modules

A. Turn key start switch and disconnect switch OFF.

B.One at a time, reconnect the electronic control modules that use the CAN Data Link.

C. Turn the disconnect switch and the key start switch to the ON position.

D. Operate the machine.

E. Check for diagnostic codes that are logged against the electronic control modules. 

Diagnostic codes are not present for the other electronic control modules. 
OK - Diagnostic codes are not present for the other electronic control modules. The initial diagnostic code may have been caused by a poor connection or a short at one of the connectors. The connector was likely one that was disconnected and reconnected during troubleshooting.

Resume normal operation of the machine.

STOP

NOT OK - DTC 967-9 is present for one of the ECM modules. The ECM has failed.

Repair: A failure of the ECM is unlikely. If the failure is not found, replace the ECM.

Prior to replacing an ECM, always contact the Technical Communicator for your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time.

See the Troubleshooting , " ECM - Replace " section of this manual for additional information.

STOP 
Begin Process For DTC 967-14 Troubleshooting HERE 
14. Check The Software

A. Use Cat ® Electronic Technician (Cat ET) to verify that the software versions for the data link modules are correct and compatible. 

The proper software is installed. 
OK - The proper software is installed.

Proceed to Test Step 15.

NOT OK - The proper software is not installed.

Repair: Flash the proper software to the appropriate ECM. Cycle the key switch to initialize the software. Ensure that the diagnostic code is no longer active.

STOP 
15. Check The Harness

A. Inspect the harness. Clean the harness connector contacts, inspect for corrosion or damage, and inspect the insulation for damage from heat, corrosion, or chafing.

B. Perform a 45 N (10 lb) pull test on each circuit wire.

C. Reconnect all harness connectors. Verify that the connectors are fully seated and the clips are fastened.

D. Use Cat ET to perform a wiggle test on the harness.

E. Turn the key switch and disconnect switch ON and operate the machine.

F. Check the status of the previously identified diagnostic code. 

The previously identified diagnostic code is no longer active. 
OK - The diagnostic code is no longer active.

Repair: The initial diagnostic code was probably caused by a poor connection at one of the connections that was inspected.

Clear the diagnostic code.

STOP

NOT OK - The diagnostic code remains active.

Proceed to Test Step 16. 
16. Check The Data Link Circuit

A. Turn the key switch and disconnect switch OFF.

B. Disconnect the harness from all ECM modules in the CAN data link circuit.

C. Measure the resistance between the harness connector contacts for the modules associated with the diagnostic code.

D. Reconnect all ECM modules. 

The resistance is greater than 5K Ω. 
OK - The resistance is greater than 5K Ω. The module associated with the troubleshooting code may have failed.

Repair: Prior to replacing an ECM contact the Technical Communicator at your dealership for possible consultation with Caterpillar. If the ECM requires replacement, see Troubleshooting, "ECM - Replace".

NOT OK - The resistance is less than 120 Ω.

Repair: If the resistance is approximately 60 Ω, check the resistance of each of the CAN resistors in the circuit. Replace the resistor that measures less than 60 Ω.

STOP

Repair: If the resistance is 5 Ω or less, the harness is shorted. Repair or replace the harness.

STOP 
Begin Process For DTC 3583-9 Troubleshooting HERE 
17. Inspect The Buttons On The Keypad.

A. Turn the disconnect switch to the OFF position.

B. Inspect the buttons for the keypad to ensure that the buttons operate smoothly.

C. Toggle each button on the keypad. 

The buttons appear to move smoothly. 
OK - The buttons appear to move smoothly.

Proceed to Test Step 12.

NOT OK - One or more of the buttons appear to be improperly activated. The face plate of the switch panel is causing one or more of the buttons to be improperly activated.

Repair: Either remove the face plate and reinstall the face plate or manipulate the buttons in order to ensure smooth operation. 
18. Check If The Diagnostic Code Remains.

A. Turn the disconnect switch and the key start switch to the ON position.

B. Clear all inactive diagnostic codes.

C. Operate the machine.

D. Check the status of the DTC 3583 -7 diagnostic code. 

The diagnostic code is NO longer active. 
OK - The diagnostic code is NO longer active. The diagnostic code does NOT exist at this time. The initial diagnostic code was probably caused by a poor electrical connection of the buttons for the Implement ECM. Resume normal machine operation.

STOP

NOT OK - The diagnostic code remains active. Failure of the ECM is unlikely.

Repair: Exit this procedure and perform this procedure again. If the cause of the problem is not found, the ECM may have failed.

Prior to replacing an ECM, always contact your Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time.  
(1) Also applies to the following DTC Codes: 296-9, 590-9, 596-9, 800-9, 967-9, and 2448-9.
(2) Also applies to the following DTC Codes: 296-14, 590-14, 596-14, 800-14, 967-14, and 2448-14.
(3) Consult your Caterpillar Authorized Dealer for the correct part numbers of the flash software.

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