Repairing Collision Damaged Wiring

Introduction

Automotive collision damage frequently causes damage to the vehicle's electrical wiring. This damage may affect critical electrical circuits that control sophisticated electronic passenger safety systems and several vital computer controlled vehicle operational systems. Therefore, the proper repair of collision damaged wiring is more important than ever, since a poor repair may directly affect the passenger's safety and proper vehicle performance. Although the sensitivity and functional requirements of wiring circuits vary, any repairs to a vehicle's wiring must be of the highest quality and long lasting, regardless of the circuit's function.

Any wiring repairs must provide a good mechanical and electrical connection, while insulating and sealing the wire from any environmental vapor or liquid that will be a catalyst for corrosion.

This bulletin will identify new wire connecting devices, materials and techniques for use in the collision repair industry that are practical and cost effective methods to repair collision damaged wiring. The products described in this bulletin may not be the only ones available to perform quality wiring repairs. The product information included in this bulletin was chosen based on function and its availability from local automotive or electronics part suppliers, and from General Motors service parts.

By using the products and techniques described in this bulletin a collision repair facility can perform high quality wiring repairs with minimal investments in training, tools and materials. Refer to the appendix section at the end of this bulletin for additional information on the following topics: basic tools & materials needed in a wire repair kit, crimp tools, heat shrink tubing, heat guns, flameless torch, and typical procedure for soldering electrical circuits.

Before Starting Repairs

NOTE:
The computers which control various systems of the automobile are very sensitive. Before disconnecting any wires or attempting any repairs, always turn the ignition key off and disconnect the battery to prevent damaging an expensive computer or control module.

Special attention should be taken to thoroughly inspect for any wiring damage while repairing a collision damaged vehicle. After wiring damage is located, the most practical method to properly perform the repair must be determined.

Some automobile manufacturers may require the entire wiring harness be replaced, if only one wire is damaged. This may be an impractical solution for several reasons. First of all, there can be a high cost for both the service part and installation labor to replace a wiring harness. Even more important, complete harness replacement requires the technician to disrupt numerous electrical circuits unrelated to the collision damage, that may cause immediate or additional long term problems. Therefore, if the damage is localized and limited to a few wires the best choice is to repair just the damaged wires.

NOTE:
If the damaged wire is contained in a short wiring pigtail which extends from a sensor or other electrical part and connects to the main wiring harness, the part containing the damaged wire should be replaced.

Repairing Damaged Insulation

When only the wire insulation appears to be damaged, carefully inspect the area to determine that no wire strands were broken. If wire strands are cut, then completely cut the wire and follow the repairs outlined under the next section on "Splicing Broken Wires."

If the damage is limited to the insulation, the insulation must be properly repaired to protect the electrical wire or connection from abrasion and moisture which could cause a short circuit or corrosion and eventual circuit failure.

The preferred solution is to use a polyolefin heat-shrinkable tubing that has an inner adhesive layer to protect a wire with damaged insulation (such as 3M's EPS-300 or equivalent). When heated, the inner layer melts and bonds itself to the original wire insulation.

An alternate preferred solution is to use an electrical moisture sealing patch or tape (such as 3M's Scotch Electrical Moisture Sealant patch/roll or equivalent). This choice for repairing damaged wire insulation is used when heat-shrinkable tubing is not practical due to connectors or wire harness configuration.

An acceptable alternative when the preferred products listed above are not possible, is to use a high quality splicing tape which is designed to protect electrical wiring and connectors from shorts and failures caused by moisture and corrosion. It should be self bonding, moisture resistant, weather resistant and have a high degree of stretch to wrap tightly around the wire or connector (such as 3M's Scotch 2242 Linerless Splicing Compound or equivalent). Splicing tape may also be identified as fusion tape.

Splicing Broken Wires

The first thing to remember is, the best electrical path is a single wire from point to point with no connections between. The unbroken, stranded wire safely inside its original PVC or crosslinked polyester insulation is very efficient. Unless it sees a drastic overcurrent condition or environmental damage (i.e. corrosion, causing increased resistance and a resulting voltage drop), that wire will last virtually indefinitely. The only reason you should ever splice a wiring harness is because the wires have already been fully or partially cut.

NOTE:
Never deliberately cut and splice any wires for the convenience of part removal or to save time. Only use factory provided removable connections to remove wires from the damaged components being repaired or replaced.

Quality wire splicing can be done without a problem. If done incorrectly you can create more of a problem than you originally intended to fix. The key to a good splice connection is understanding what you must accomplish and what can go wrong when you do it incorrectly.

In making any repair splices, you must get the wire-to-wire junction back as close to original as possible. This includes not only the electrical connection, but also mechanical features such as the physical connection (i.e. to withstand any tension or vibration), wire sealing and supporting the wire in its original location.

The electrical connection itself can be made by either soldering the wires or by crimping them together with a mating terminal such as a butt splice. The disadvantage of using solder is that if you don't have a sound mechanical connection, you run the risk of motion occurring between the wires before the solder is totally solid. That results in a pasty, or cold, solder joint. Another disadvantage is the higher degree of knowledge, experience and cleanliness required by the technician to properly perform a solder joint connection.

In making a good solder joint, the potential problem of capillary action exists. The multiple strands of copper in the wire can soak up solder, solder flux and eventually salt and other liquid contaminants. If solder wicks back into the wire, it becomes stiff because the strands are soldered together. Solder flux and salt wicking can cause hiddencorrosion, as well. As a result, solder may not always be the best solution and should be the second choice, unless the repair location or the manufacturer specifically requires it.

Although the typical soldering procedure may not be favorable, the use of the SSC-200x series Solder Splice Connector made by 3M is a viable alternative. Refer to section titled "New Products for Fast & Complete Wire Repair" on for more specific information.

The alternative to soldering is to use a solderless butt splice wire connection. A butt splice is basically an open-ended copper cylinder. The objective is to strip the insulation from the wire ends, then insert them into the opposite ends of the cylinder. The cylinder is then crimped to mechanically lock the splice connector to the stranded wire.

The advantages of butt-splicing include: proper alignment of the junction with the lay of the wire, lack of capillary stiffening associated with soldering, and minimal knowledge or experience is required to achieve good results. Butt splices can also be used on non-solderable wires such as stranded stainless steel or aluminum wire.

The problems with typical butt splice connectors (those commonly found in many stores) are: the plastic overshield alone can not adequately protect the joint from corrosion elements, and the metal cylinder does not always crimp evenly to securely lock the wires together. A proper mechanical connection is dependent on the cylinder material and the tool used to deform or crimp the connector. Often, the size of the butt splice connector chosen by the technician does not properly match the wire size being joined. This leads to poor crimping and the splice does not securely hold the wires. It is very important to select the proper size butt splice connector for the wire being joined, along with using a professional grade crimping tool as described by the manufacturer of the butt splice connector. To assist on converting metric wire sizes to English wire gauge sizes see the conversion chart.

The butt splice offers the simplest wire connection method with the best results, if made with quality connectors and the proper crimping tool. Be sure the butt splice connector matches the gage of wire you are splicing.

Sealing the Splice Joint

The last concern in making a quality splice joint is to protect the spliced wire from environmental factors which may cause corrosion and subsequent electrical failure. Several different materials have been used in the past (i.e. PVC electrical tape, silicone RTV and heat-shrink tubing), which are adequate for immediate electrical insulation but the long term effectiveness falls short of the corrosion protection necessary for today's automotive electrical circuits.

New and better products have been developed recently, which are now available for protecting the repaired wire joint from corrosion. There are new fusion and splicing tapes to wrap repaired wire joints. New professional grade butt splice connectors are available that will provide superior wire connection both mechanically and electrically, along with sealing the joint from corrosion with one connector. The complete wire splice joint is accomplished in three easy steps: 1) cut & strip the wires, 2) insert wires into connector & crimp, 3) heat the heat-shrinkable insulation layer. While heating the insulation the inner adhesive layer melts, gluing itself to the wire insulation to effectively seal the splice joint. Both AMP and General Motors Packard Electric have this type of crimp & seal butt splice connector. See Photograph 1.

3M has a variation of the crimp & seal connector which does NOT require a special crimping tool, since there is no crimping operation. The solder splice connector contains a solder disc inside that melts to solder the wire strands together, when heat is applied. Continued heating melts the thermoplastic dams and shrinks the heat-shrinkable insulation and seals itself to the wire insulation. Also available from 3M is a heat-shrinkable tubing which also has an inner adhesive layer that seals to the wire insulation when heated.

More detailed information on these and other products are described in the next section titled "New Products For Fast & Complete Wire Repair."

NOTE:
Only use a hot air gun with the recommended heat range setting to heat solder splice connectors, heat-shrinkable insulation on some types of butt splice connectors, and heat-shrinkable tubing. DO NOT USE A DIRECT FLAME, it may start the insulation on fire.

The final step to complete the wiring repair is to place it back into the plastic tubing or wrap it into the wire bundle, if it was removed to perform the repair. Then secure the wire harness or wire bundle in its original location to prevent movement. When the wiring is restored to pre-accident condition and location, re-connect the battery.

REMINDER:
To achieve a good splice joint, you first must have the correct type and size splice connector for the wire being repaired. The second requirement is that you MUST use the crimp application tool from the connector manufacturer that is designed and made for the particular brand and size splice connector being used.

New Products for Fast & Complete Wire Repair
3M Automotive and Electrical Trade Divisions

For information contact your local automotive parts supplier, body shop supplier, or electronics supply store. Products and cost may vary between suppliers.

1. SSC-200x Series, Solder Splice Connector

This system does not require a crimp tool, just a standard heat gun designed for solder-type connectors. The 3M Solder Splice Connector is ideal for wire harness fabrication and repair in a variety of industries. (The Solder Splice Connector is currently in the 3M Industrial product line, the Automotive product line part number will be available soon.)

Description: The 3M SSC-200x is a one piece design. It is insulated with a flame-retardant, heat-shrinkable sleeve of 3M's new flexible THV fluoropolymer. THV offers outstanding clarity of the insulation sleeve which allows easy inspection of the connection. Inside the sleeve are colored thermoplastic sealing dams and a wire-locking barrel with a fluxed solder disk.

After wires are inserted and held in place by the barrel wire locks, heat is applied and three events occur:

• The solder disk melts and connects the wires.
• The colored thermoplastic dams melt and flow, forming the moisture seal.
• The sleeve shrinks, forming the electrical insulation.

The splice prepared with the 3M SSC-200x Solder Splice Connectors are accomplished in two easy steps. First the wires are stripped (3/16" from the end) and inserted into the connector. The wire lock feature holds the wire(s) in place until a permanent solder connection is made. See Photograph 2.

Second, heat is applied until the solder disk melts and the solder connection is made. Single or multiple wires can be inserted into each end at the same time in parallel, making sure each wire is placed up to the solder disk which acts. as a wire stop.

The solder splice connector MUST be heated in a horizontal position, with the visual opening facing up. This allows the liquid solder to flood the lower portion of the connector containing the wires to be joined. See Photograph 3.

A preferred heat gun is Steinel model HG3000SLE with the 07461 14 mm reflector nozzle. The temperature setting should be set to number 10 which is an air temperature of 650°F (345°C) and the air flow set to maximum. Caution: Heat gun air temperatures exceeding 700°F (370°C) should be avoided to prevent electrical insulation failure. Other heat guns may be suitable as long as the air temperature does NOT exceed 700°F (370°C).

After the solder flows, the connector is moved to each side, applying heat to the colored insert dams to shrink the tubing and melt the sealant. The clear insulation tubing will allow for inspection to see that the solder pellet is melted, the conductors are coated with the solder, and that the colored insert dams are melted among the wires.

Size selection: Generally, the 3M SSC-200x Solder Splice Connectors work well with any wire or combination of wires that can be easily inserted into the connector.

Remember, the 3M Solder Splice Connectors are NOT tied to specific wire gauges, each size reliably splices a wide range of wire sizes. When selecting a connector, select smallest applicable size.

2. EPS-300 Heat-Shrikable Tubing

Description: All weather, heat-shrinkable, dual wall, polyolefin tubing for automotive applications. 3M EPS-300 Heat-Shrinkable Tubing offers automotive electrical and environment protection for electronic components, wire splices, wire bundles, and harness breakouts. EPS-300 is a superb insulator that also functions as a strain relief and an environmental seal. An internal layer of special thermoplastic adhesive melts when the heat-shrinkable tubing is heated, forcing the melted adhesive to flow and seal the substrate as the tubing shrinks. Upon cooling, the adhesive solidifies, forming a permanent flexible and waterproof barrier. Sizes other than what is listed below are available, in diameters of 3/4", 1", 1-1/2" and 2".

3. Scotch Electrical Moisture Sealant

Description: Provides a quick and easy method of moisture proofing automotive vehicle electrical connections. The mastic forms a moisture tight seal around connections and the tough elastic vinyl backing provides additional protection against vibration, road grime and abrasion that are constant problems encountered on a vehicle.

4. Scotch 2242 Linerless Splicing Compound (Fusion Type)

Description: SCOTCH 2242 Linerless Splicing Compound is designed to offer the ultimate in protection of electrical wiring and connectors from shorts and failures caused by moisture and corrosion. It is self bonding, moisture resistant, weather resistant - will not crack or embrittle in ultraviolet light or cold temperatures. Its high degree of stretch allows for tight wrapping of wires and connectors.

Product: Roll 3/4" x 15', part # 06155

AMP Incorporated

For information, catalogs or distributor locations near you: call the AMP Product Information Center at 1-800-522-6752. Products and cost may vary between suppliers.

1. Pre-Insulated Sealed Terminals and Splices (catalog # 82602)

AMP Pre-Insulated Sealed Connectors are environmentally sealed to prevent corrosion from fluids and vapors. The tin plated copper connector body has a color-coded insulator. The heavy duty polyolefin heat-shrinkable insulator sleeve provides: exceptional insulation, a moisture-proof seal to prevent corrosion, wire support and permits visual inspection. Available tooling provides a firm mechanical crimp, assuring electrical integrity. These one piece connectors allows fast, easy terminations. Photograph 1 shows the Seal 'N Splice connector after the wires are joined and sealed. This connector is very favorable when appearance is important, along with providing a high quality splice joint repair.

Description: BUTT SPLICE CONNECTORS

Description: Application CRIMP TOOL

Use tool part # 55893-1 for 22-10 AWG size wire connectors
Use tool part # 55894-1 for 16-8 AWG size wire connectors

Description: Seal 'N Splice Kit

(contains: crimp tool # 55893-1, assorted 22-10 AWG connectors and carrying case) Kit part # 55892-1

General Motors, Packard Electric

For information contact your local General Motors Dealer parts department. Products and cost may vary between dealers. List prices are shown.

1. Solder Splice Clip

Description: The Solder Splice Clip is used to crimp the wires together for a mechanical connection before soldering the wires together.

Small Clip, part # 01839906
Large Clip, part # 05297428

2. Crimp and Seal Splice Sleeve

Description: Insulated crimp splicing sleeve with insulating heat shrink tubing that is adhesive lined which liquefies when heat is applied to shrink the insulation tubing, as it is heated the adhesive melts and bonds to the wire insulation sealing the joint.

3. Splice Crimper Tool

Description: Plier style tool for crimping the "crimp and seal splice sleeves."

Part # J38125-8

4. Ultratorch

Description: Gas fueled device used to heat splice sleeves.
Part # J381125-5

5. 1988 Essential Tool Kit

Description: This kit include the instructions, tools and selected terminals to repair wiring components produced by Packard Electric on GM vehicles. This kit contains: 39 different high volume terminals, 3 environmental seals, 3 different crimp & seal splice sleeve sizes, 2 different splice clip sizes, 5 standard removal tools, 3 crimp tools, ultratorch, tweezers, and an instruction manual. The kit also includes terminal identification, proper methods & tools for removing terminals from connector, replacing terminals, and splicing wires. The recommended methods and tools will produce a quality repair, both electrically and functionally. Each portion of the kit can be purchased separately from General Motors Service Parts Operation.

Part # J38125A

Appendix

Basic Tools & Materials Needed in a Wire Repair Kit:

1. Wire insulation stripper tool
2. Butt splice connector sleeves
3. Crimping tool
4. Heat shrink tubing
5. Flameless torch or a heat gun (no open flame)
6. Electrical moisture sealant products (tape or liquid)
7. Electrical tape, only high quality tape
8. Solder - (60/40) rosin core, meaning (60% Tin / 40% Lead by weight with a resin core flux in the center of the solder), melting range is 362-374°F (183-190°C)
9. Soldering iron, low wattage (15 - 35 watts) pencil-type
10. Replacement terminals, only high quality terminals or O.E.M. supplied

Crimp Tools:

• are used to properly crimp butt splice sleeves or terminals.
• need to match the connector size being used.
• with multiple crimp sizes must utilize the crimping location on the tool that matches the specific size of splice sleeve being used.
• may utilize a ratchet to prevent tool removal before it fully compresses the splice sleeve

Heat Shrinking Tubing:

• is a thin wall tube made of a special heat-shrinkable plastic material used to cover the repaired area of wire to provide insulation and abrasion protection.
• can also be used to provide additional electrical or mechanical protection over a wire in an severe environment.
• comes in several sizes to fit any applications, so choosing the correct size is determined by the minimal shrink diameter.
• is placed over the wire before it is re-connected or repaired and it should extend beyond the splice joint at least 1/2 to 3/4 of an inch.
• should be heated as directed by the manufacturer, then its diameter shrinks, tightly forming itself to the repaired wire.
• can have an inside diameter two to three times the size wire or splice joint being covered, when installed over the wire before making the splice joint.
• can be cured or shrunk best with a hot air gun, although a hair drier can be used.

Heat Guns:

• are used to heat the shrinkable/sealing insulation sleeve on splice connectors and to heat all types of protective heat-shrink tubing
• are produced by several manufacturers and several different models are available to meet various production or repair requirements.
• should be chosen for the correct heating capacity (temperature and air flow) for the intended application, some types are adjustable.
• can cost as low as $50 and as high as $175 for a high capacity deluxe model with adjustable heat settings and air flow.
• of a specific model or type may be recommended by the manufacturer of the connectors being used, purchase the correct model for your application to achieve quality results.

Flameless Torch:

• can be used to heat the shrinkable/sealing insulation sleeve on splice connectors and to heat all types of protective heat-shrink tubing.
• may have interchangeable tips and a soldering tip may also be available.

Typical Procedure for Soldering Electrical Circits:

1. Mechanically secure wires together with solder splice sleeve, or hold wires securely to avoid any movement during solder operation.
2. Use low wattage pencil-type soldering iron (15 - 35 watt) or a flameless torch with a soldering tip may be used, but adjust the torch to a low tip. DO NOT use a high wattage solder gun, it may create a voltage spike or over heating that could damage electrical parts.
3. Make sure the soldering iron is not corroded, if corroded clean it with a fine single cut file until it is clean and smooth.
4. Tin the tip of the soldering iron before use, this is done by applying solder to the tip of the hot iron, then wiping it off.
5. Remember to keep the soldering tip clean during use.
6. Use 60/40 (60% tin / 40% lead) rosin-core flux solder.
7. Apply heat to the bottom of the wire until the wire is hot enough to melt the solder, this is determined by slightly touching the solder to the wire.
8. After the wires are hot enough apply solder from the top, enough to apply a thin coat of solder letting it flow to reach all parts of the splice joint. Do NOT apply solder to build up a lump on the joint or allow it to flow into the insulation.
9. A good solder joint should be entirely covered with a thin coat of glossy solder.

The information provided in this bulletin is for educational purposes only. Although every effort has been made to ensure the accuracy of the information contained in this bulletin, Tech-Cor assumes no responsibility or liability for any repairs performed using information from any publication issued by Tech-Cor.

Any person performing repairs must determine whether any suggested or recommended procedures or repairs are suitable or appropriate for the particular vehicle being repaired. The repairer remains solely responsible for such determination, as well as for the proper completion of the repairs.

Reproduction of this bulletin is not permitted without the written approval of Tech-Cor.