770G and 772G Off-Highway Truck/Tractors Caterpillar


Electrical Connector - Inspect

Usage:

770G ECM
Reference: Special Instruction, SEHS9615, "Servicing DT Connectors".

Reference: Special Instruction, REHS0148, "Listing Of Deutsch Connector Components"

Reference: Special Instruction, SEHS9065, "Use Of CE Connector Tools".

Reference: Service Magazine, SEPD0342, 27, January 97, "Field Repair Of Single Wire Breaks In Harnesses (Sealed Splice)".

Reference: Service Magazine, SEPD0371, 28, July 97, "Protection Of Unsealed Electrical Terminations For Machines In Corrosive Applications".

Reference: Service Magazine, SEPD0473, 24, May 99, "New DT Connector Plugs With Improved Seal Retention".

Reference: Service Magazine, SEPD0545, 09, October 00, "Dielectric Grease Should Not Be Used In Electrical Connectors".

Reference: Pocket Guide, SEBD0402, "Guidelines For Routing And Installing Wire Harness Assemblies".

This information will assist in detecting problems with connectors and with wiring. If a problem is found, correct the condition and verify that the problem is resolved.

Disconnecting and reconnecting connectors sometimes resolve intermittent electrical problems. Checking for diagnostic codes immediately before disconnecting a connector is important. Also check for diagnostic codes after reconnecting the connector. If the status of a diagnostic code is changed due to disconnecting and reconnecting a connector, there are several possible reasons. The likely reasons are loose terminals, improperly crimped terminals, moisture, corrosion, and inadequate mating of a connection.

Important Safety Information

Work safely. Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs.

A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools in order to perform these functions properly.

Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard.

Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive. If a tool, procedure, work method, or operating technique, not recommended by Caterpillar is used, make sure that the procedure is safe for all people.

Make sure that the product will not be damaged or be made unsafe by the operation, lubrication, maintenance, or the repair procedures that are used.

Guidelines

  • Always use a 1U-5804 Crimp Tool (12-GA TO 18-GA) to service Deutsch HD and DT connectors. Never solder the terminals onto the wires. Refer to Tool Operating Manual, SEHS9615, "Servicing Deutsch HD and DT Style Connectors".

  • Always use a 147-6456 Wedge Removal Tool in order to remove wedges from DT connectors. Never use a screwdriver to pry a wedge from a connector.

  • Always use a breakout harness for a voltmeter probe or a test light. Never break the insulation of a wire in order to access to a circuit for measurements.

  • If a wire is cut, always install a new terminal for the repair.

Tests

Check Connectors for Moisture and Corrosion



Illustration 1g01960167
(1) Former Seal Design
(2) Current Seal Design

The plug end of the DT connector has a seal at the mating end of the connector. This seal has been improved on black connectors in order to help prevent slipping. Additionally, this seal is replaceable. This improvement will help keep moisture and dirt from entering the connector.

The current seal design (2) is not interchangeable with the former design (1). The receptacle has also changed to the new colors.



Illustration 2g01960176
(3) Seal for a three-pin connector (typical example)

Table 1
Troubleshooting Test Steps  Values  Results 
1. Inspect All Wiring Harnesses

A. Ensure that the routing of the wiring harness allows the wires to enter the face of each connector at a perpendicular angle. (Otherwise, the wire will deform the seal bore. This condition will create a path for the entrance of moisture.)

B. Verify that the seals for the wires are sealing correctly.

C. Disconnect the suspect connector and inspect the connector seal. Ensure that the seals are in good condition. If necessary, replace the connector.

D. Thoroughly inspect the connectors for evidence of moisture entry. 

The harness wiring, connectors, and seals are in good condition.
There is no evidence of moisture in the connectors. 
OK - The harness wiring, connectors, and seals are in good condition.

Proceed to "Check the Wires for Damage to the Insulation".

NOT OK - A problem has been found with the harness or the connectors.

Repair: Repair the connectors or the wiring, as required. Ensure that all of the seals are properly in place. Ensure that the connectors have been reattached. If corrosion is evident on the pins, sockets or the connector, use only denatured alcohol to remove the corrosion. Use a cotton swab or a soft brush to remove the corrosion. If moisture was found in the connectors, run the engine for several minutes and check again for moisture. If moisture reappears, the moisture is wicking into the connector. Even if the moisture entry path is repaired, replacing the wires may be necessary. Verify that the repair eliminates the problem.

STOP 

Some minor seal abrasion on connector seals is normal. Minor seal abrasion will not allow the entry of moisture. If moisture or corrosion is evident in the connector, the source of the moisture entry must be found and repaired. If the source of the moisture entry is not repaired, the problem will recur. Simply drying the connector will not fix the problem. Check the following items for the possible moisture entry path:

  • Missing seals

  • Improperly installed seals

  • Nicks in exposed insulation

  • Improperly mated connectors

Moisture can also travel to a connector through the inside of a wire. If moisture is found in a connector, thoroughly check the connectors harness for damage. Also check other connectors that share the harness for moisture.

Check the Wires for Damage to the Insulation

Carefully inspect each wire for signs of abrasion, of nicks, and of cuts. Inspect the wires for the following conditions:

  • Exposed insulation

  • Rubbing of a wire against the chassis

  • Rubbing of a wire against a sharp point

Table 2
Troubleshooting Test Steps  Values  Results 
1. Check All Wiring Harness Fasteners

A. Check all of the fasteners to verify that the harness is secure and is NOT compressed.

B. Pull back the harness sleeves to check for a flattened portion of wire. (A fastener that has been overtightened will flatten the harness.) 

The wires are free of abrasion, of nicks, and of cuts and the harness is properly clamped. 
OK - The harness has passed all checks.

Proceed to "Inspect the Connector Terminals".

NOT OK - There is damage to the harness.

Repair: Repair the wires or replace the wires, as required. Verify that the repair eliminates the problem.

STOP 

Inspect the Connector Terminals

Table 3
Troubleshooting Test Steps  Values  Results 
1. Visually inspect each terminal in the connector.

A. Verify that the terminals are not damaged. Verify that the terminals are properly aligned in the connector and verify that the terminals are properly located in the connector. 

The terminals are properly aligned and the terminals appear undamaged. 
OK - The terminals show no signs of damage.

Proceed to "Check Individual Pin Retention into the Socket".

NOT OK - The terminals of the connector are damaged.

Repair: Repair the terminals and/or replace the terminals, as required. Verify that the repair eliminates the problem.

STOP 

Perform a Pull Test on Each Wire Terminal Connection



Illustration 3g02732798
(4) Locking Wedge for 3-pin connector

Table 4
Troubleshooting Test Steps  Values  Results 
1. Check Locking Wedge Of Connector.

A. Ensure that the locking wedge for the connector is installed properly. (Refer to the figure above.)

B. Perform the 45 N (10 lb) pull test on each wire. (Each terminal and each connector should easily withstand 45 N (10 lb) of tension and each wire should remain in the connector body.) 

This test confirms that the wire was properly crimped in the terminal and the terminal was properly inserted into the connector. 
OK - All terminals pass the pull test.

Proceed to "Check Individual Pin Retention into the Socket".

NOT OK - A wire has been pulled from a terminal or a terminal has been pulled from the connector.

Repair: Use the 1U-5804 Crimp Tool (12-GA TO 18-GA) to replace the terminal. Replace damaged connectors, as required. Verify that the repair eliminates the problem.

STOP 

Check Individual Pin Retention into the Socket

Table 5
Troubleshooting Test Steps  Values  Results 
1. Confirm Pin Retention At Sockets.

A. Disconnect the harness.

B. Insert a new pin into each socket of the mating plug individually to check for a good grip on the pin by the socket. 

The sockets provide good retention for the new pin. 
OK - The terminals are OK.

Proceed to "Check the Locking Mechanism of the Connectors".

NOT OK - Terminals are damaged.

Repair: Use the 1U-5804 Crimp Tool (12-GA TO 18-GA) to replace the damaged terminals. Verify that the repair eliminates the problem.

STOP 

Check the Locking Mechanism of the Connectors

Table 6
Troubleshooting Test Steps  Values  Results 
1. Check Locking Mechanism Of Connectors.

A. Lock the connectors, and ensure that the two halves cannot be pulled apart.

B. Verify that the latch tab of the connector is properly latched. Also verify that the latch tab of the connector returns to the locked position. 

The connectors lock securely. No cracks or breaks are found at the connectors. 
OK - The connectors are in good condition.

Proceed to "Perform the Wiggle Test on the Cat Electronic Technician (Cat ET)".

NOT OK - A connector locking mechanism is damaged or missing.

Repair: Repair the connector or replace the connector, as required. Verify that the repair eliminates the problem.

STOP 

Perform the Wiggle Test on the Cat Electronic Technician (Cat ET)

Table 7
Troubleshooting Test Steps  Values  Results 
1. Perform A Wiggle Test.

A. Select the Wiggle Test from the diagnostic tests on Cat ET.

B. Choose the appropriate group of parameters to monitor.

C. Press the "Start" button. Wiggle the wiring harness in order to reproduce intermittent problems.

If an intermittent problem exists, the status will be highlighted and an audible beep will be heard. 

No intermittent problems were indicated during the Wiggle Test. 
OK - No intermittent problems were found. The harness and connectors appear to be OK. If another procedure recommended this test, return to that procedure and continue testing. If the problem has been resolved, return the machine to service.

STOP

NOT OK - At least one intermittent problem was indicated.

Repair: Repair the harness or the connector. Verify that the repair eliminates the problem.

STOP 

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