Truck Wiring and Lighting: 9 Common Causes of Failure
(Courtesy of Grote Industries)
**Moisture & Corrosion: Condensed water droplets inside a lens or corrosion around a lamp socket are sure signs that moisture has penetrated the system. Water can enter the system through ineffective wire seals, unprotected splices, unsealed crimps and connectors and non-mating seals. When making repairs, don't replace a sealed system with unsealed components. Make certain that connector seals are in place and undamaged. Inspect them carefully for cuts, tears and punctures.
**Chemical Damage: Continuous exposure to many of the common chemicals found in and around trucks can cause plastics to swell, crack, soften or otherwise become degraded. Diesel fuel and hot engine oil are the main culprits. To minimize the effects of chemicals, inspect the wiring for signs of degradation. If it is occurring in an area that is generally free from contamination, check for leaky hoses, gaskets or fittings, and repair if damaged or leaking. To avoid damage from chemicals, don't run wiring in areas where the chance for continuous exposure is likely, such as under fuel lines and filters.
**Abrasion: Abrasion occurs when wires or wire wraps are allowed to rub against frame members or other abrasive surfaces. Once the insulation is worn away, bare conductors may contact a ground surface and create a grounded circuit. Or, it could cause wear to the point of fracture, resulting in an open circuit. Using the proper routing and coverings will help to prevent wear areas and abrasive damage. Worn coverings such as loom, convoluted tubing or spiral wrap should be replaced if they are no longer providing sufficient protection for the wires inside.
**Impact: Lighting and wiring must be protected from the impact of rocks, gravel, and other road debris. A major impact can cause enough damage to require extensive repairs. Smaller, more frequent impacts over time may deliver equally extensive damage. Damage from impacts can do damage although the wires are contained in a loom or other covering. During inspection, always check for damage from impacts and replace and wiring or lights that appear to be damaged. Make certain that the replacement parts are equivalent to or better than the original.
**Vibration: Broken lamp filaments are one of the most common problems caused by vibration, but it can also lead to the abrasion of mating surfaces which causes connectors and splices to fail. To minimize vibration problems, make certain that all wires and connectors are secured appropriately. Always secure the wiring as it exits the connector. Use cushioned mountings for lamps in applications where vibration failure is excessive.
**Grit & Sand: Accumulation of abrasive materials can lead to damage, especially when combined with vibration. If gritty materials enter connections, it can accelerate the wear contact points causing interruption of the circuit and failure of the devices. Sand and grit can also attract and hold moisture, creating conditions conducive to corrosion. In some cases, sand and grit may work their way inside protective coverings and abrade the insulation of wires running through it if there is relative motion between the covering and the wire. One of the ways of reducing sand and grit buildup is to eliminate abrasive materials in the areas where wiring is present. Another way is to seal openings on protective coverings to keep gritty materials from entering.
**Extreme Temp: There are a variety of conditions that lead to extreme temperature buildup which can damage lighting and wiring. These include leaving a trailer's tail lights on when the trailer is backed up to a dock and air flow around the light is prohibited. When lights have been damaged from heat buildup, the lenses are often bubbled and misshapen. Where extreme temperatures can't be avoided, special heat-resistant wires and materials should be used.