Guidelines for Routing and Installing Wire Harness Assemblies {1408, 7553} Caterpillar

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Introduction

Customer satisfaction is the highest priority. All wiring harnesses must yield a high degree of reliability and dependability .

This Special Instruction is intended to provide a quick reference for the wire harness routing, clipping, connectors, and terminals. The following examples should be used as a reference.

Some Caterpillar products may have exceptions to these guidelines. In these cases, the Service Manual will supersede this publication.

The material in this Special Instruction will cover typical shop repairs or field repairs on Caterpillar products.

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, a procedure, a work method, or operating technique that is not recommended by Caterpillar is used, the user must ensure that it is safe for the user and for other people to use.

The user should ensure that the product will not be damaged or the product will be made unsafe by the operation, lubrication, maintenance, or the repair procedures that are used.

Removal

• Before performing any maintenance on any Caterpillar products, ensure that the key start switch and the disconnect switch are in the OFF position. Many maintenance procedures will also require the battery to be disconnected. Refer to the Service Manual for the product that is being serviced.

• Prior to removal of any harnesses or connectors, make a note of the harness routing and placement of all connectors. A diagram of the harness routing will aid in reinstalling the harness to the original orientation.

• Refer to the Disassembly and Assembly Manual for the proper routing of a harness for the product that is being serviced.

• A wrench, a screwdriver, or a pair of pliers should NOT be used to unplug connectors.

• The following is a typical sequence that is used to remove a harness:

Illustration 1	g02068173

1. Refer to the Service Manual for specific information about the product that is being serviced.

2. If necessary, remove the connector from the mounting point.

3. Depress the latching mechanism fully.

4. Unplug the connector. Do not pull on the wires in order to separate the two halves.

5. Remove the harness from the clipped locations.

Handling

• Proper storage and handling techniques can prevent accidental harness damage or connector damage as well as the loss of seals

• Do not remove harnesses from the shipping bags until the harness is ready to be used. Ensure that the part number is correct

• The handling of wire harnesses should be done with care

• DO NOT drag a harness across the ground

• Do not tug on any portion of a wire harness

• Do not jerk on any portion of a wire harness

Illustration 2	g02068234

• The harness should not be bent into a shape that could pinch the wire

Routing

• Proper routing of the battery cables will prevent rubbing, chafing, and abrasions that are caused by wire movement

• Route wiring harnesses away from sharp edges, rotating parts, or high temperature zones. Proper routing of the harness will ensure that the harness remains in good serviceable condition

Illustration 3	g02068314

• The engine and the transmission will move with respect to the frame. Hydraulic hoses flex as pressure is applied. General vibration will require proper routing of the wire harnesses to avoid rubbing and chafing

• Route the wiring harness so that the wires are straight when entering the connector. Moisture may enter the connector if the wires are not straight

Illustration 4	g02068333

• A wiring harness should not be routed against fuel lines or fuel fittings

Illustration 5	g02068334

• Some sensors and electronic components have hard seals (potting) that allow the wires to enter the connector at an angle. Correct the wire harness or adjust the wire harness in order to prevent any moisture from entering, if a potential entry point for moisture is found

• If a potential point of entry for moisture is detected in the potting due to deterioration of the potting, use 8T-0065 Silicone Sealant to seal the potential point of entry. Ensure that all areas are clean and free of dirt, oil, and corrosion before sealant is applied

Flexing Applications

The following information applies to certain applications when flexing of the harness is required during normal machine operations. Some examples of flexing applications are articulation joints and scraper hitches.

• In flexing applications, heat shrink tubing or rubber sleeves should be used as a stress relief for wires that enter the protective hose or conduit and exit the protective hose or conduit. The heat shrink tubing or rubber sleeves will help prevent sharp bending of the wires

• In flexing applications, wires that are inside the hose should not be braided, taped, clipped, or spliced. Allow sliding motion between the wires. Clipping or taping wires can cause concentrated bend points and localized stress points. Taping the wires during the harness construction can result in crossed, kinked, or twisted wires that can cause concentrated bend points

Illustration 6	g02068335

• Route wires through the appropriate hose or conduit in order to control the bend radius of the harness. Always ensure that the required bend radius for the wire harness will equal or exceed the minimum bend radius for the size of the hose or conduit

Clipping

• As a rule, clipping points should be approximately 450 mm (18 inch) from each other. Generally, clips should be located 150 mm (6 inch) from the rear of the connector

• Wiring harnesses should be supported in order to prevent an excessively loose harness

• Linkage cables, and hoses should NOT be tie-wrapped to any harness, cable, or fuel line

• Care should be taken in order to prevent wires, harnesses, and cables from contacting rough cast structures, sharp edges, or other abrasive structures. A grommet should be used whenever a wire, a harness, or a cable passes through a sheet metal surface

• Wiring harnesses should not be allowed to rub against the surface that the harness contacts

• The clips should hold the harness firmly in order to prevent the harness from sliding in the clip

• Clips should be around the braiding of the harness. Do not use clips on wires that are not braided

• Clips can be used directly on larger wires. Battery cables are an example. Care should be taken in order to ensure that the proper clip and the proper size of the clip is used

Illustration 7	g02071075

• In some cases, green tape on the wire harness will show the proper location for a clip to be installed

• Multiple harnesses should not be routed in the same clip. Individual clips should be used for each harness

• If a harness is located in an area that will require the frequent removal of a harness clip, a conventional P-Clip should be used

Illustration 8	g02068476

• Clips should be used on harnesses with a large diameter in order to support the harness adequately

• When tie straps are used, links or ladder clips should be used. Fasten the link or ladder clip securely to the product

• Make sure that only tie-wraps that are approved by Caterpillar are used

• As a rule, 3S-2093 Cable Straps are used on harnesses that are less than 15 mm (0.5 inch) in diameter and 7K-1181 Cable Straps are used on harnesses of more than 15 mm (0.5 inch) in diameter

• The cable straps should be installed by using the 4C-5877 Installer Tool to apply a force of 135 N (30 lb) to 155 N (35 lb) to the cable strap

• Multiple harnesses may be attached with cable straps. Ensure that the cable straps maintain the required spacing. A cable strap should be used through each link along the route of the harness

• Ensure that the harness is attached to the links or ladder clips so that the harness will not rub against abrasive areas. Examples of abrasive areas are the splatter from welding, rough edges, and sharp edges

Connectors

• Ensure that all connectors have the seals in place before mating the connectors together. Ensure that the connectors and seals are clean and free of moisture

• Ensure that both connector ends are properly mated. Gently attempt to separate the connector. If the connectors do not separate, then the connectors are locked together

Illustration 9	g02068517

• Proper storage and handling of the harness can prevent losing a seal or seal damage

Illustration 10	g02068525
Clips and tie-wraps should be no closer than 150 mm (6 inch) from a connector.

• Most connectors on Caterpillar products are designed to be mounted in the horizontal position. Clipping a harness too close to a connector can introduce moisture and wire strain

Illustration 11	g02068541

Illustration 12	g02068544

• Connectors that are not being used should be sealed. Use the mating connector and seal all holes with sealing plugs. See the "Reference Material" at the end

• Pin and socket locations that are not being used should be sealed with sealing plugs. See the "Reference Material" at the end.

• Coupling nuts on military connectors should be locked with a lockwire. The nut should be tightened in a clockwise direction by using 6V-0006 Connector Pliers

• Retaining clips for Sure Seal connectors must not be used to support the weight of the harness. Using the retaining clips to support the weight of the harness could cause stress on the contacts. Stress on the contacts could cause the contacts to pull out of the connector or the contacts could break

Terminals

• Ring terminals that are too large may loosen or the terminal could break. Proper contact of the ring terminal to the post may also not be correct

Illustration 13	g02068573

• When you use a ring terminal, ensure that the proper size of ring terminal is used for the post. Illustration 13 shows an example of a terminal that is the correct size for the bolt

Illustration 14	g02068593

• Flat washers are recommended and should be placed between the screw head or the nut and the wire or the cable terminal to allow tightening without causing the wire or cable to walk around the screw or stud

• If a star washer is used, the washer should be placed between the wire terminal or the cable terminal and the component

Batteries

Illustration 15	g02068653

Illustration 16	g02068657

Battery Cable Colors

• A battery cable with 24 V potential shall be red with red protective boots (1) at both ends

• Battery cables that are between batteries with a 12 V potential shall be red with a red protective boot (1) at the positive battery post and a black protective boot (2) at the negative battery post

• A black protective boot (2) shall be applied at the battery terminal of the disconnect switch

• Red protective boots (1) shall be used on alternator + battery terminals. A red protective boot (1) should be used to cover the "B+" terminal and "R" terminal

Routing the Battery Cables

• Battery cables should be routed in order to avoid contact with other objects

• Battery cables, cables for the alternator, and other types of electrical cables should have the appropriate boot in place

• The correct clip should be used and installed directly on larger wires. An example of a large wire is the battery cables

• Battery cables and harnesses require extra attention to ensure proper operation

• Battery cables and harnesses should not be run together in the same clip

• The battery cable should be clipped to the engine block prior to routing to the starting motor terminals

Reference Material

• Special Instruction, SEHS9615, "Servicing Deutsch HD and DT Style Connectors"

• Special Instruction, SEHS9065, "Use of CE/VE Connector Tools"

• Special Instruction, REHS0148, "Parts Listing of the Deutch Connectors and Components"

• Special Publication, SEBD0983, "Ugly Electrical References"

• Service Magazine, SEBD1960, 27, March 1989, "Understanding Shorts, Opens, and Intermittents"

• Service Magazine, SEBD1960, 27, March 1989, "How to Troubleshoot a Short-To-Ground in Power Wiring"

• Service Magazine, SEPD0447, 07, December 1998, "Identification of External Terminals on Alternators"

• Service Magazine, SEPD1960, 27, March 1989, "Understanding Causes of Blown Fuses and Tripped Circuit Breakers"

• Service Magazine, SEPD0342, 27, January 1997, "Field Repair of Single Wire Breaks in Harnesses"

• Service Magazine, SEPD0371, 28, July 1997, "Protection of Unsealed Electrical Terminations for Machines Used in Corrosive Applications"

• Service Magazine, SEPD0473, 24, May 1999, "New DT Connector Plugs With Improved Seal Retention"