Eye on the Industry: Lighting failure checklist

The thing to remember when diagnosing lighting system problems is that the lamp may not be the culprit. Never automatically assume that because it seems as though the lamp has failed, it’s the lamp’s fault-you must determine the root cause of the problem so that more serious lighting system problems don’t occur.

Brad Van Riper, senior vice president and chief of technology, Truck-Lite Co., said that the natural inclination has long been to assume that the light has failed when it no longer functions.

“People have been conditioned to this approach with home lighting and passenger car lighting by automatically replacing the bulb when they see a failure, but in the heavy-duty lighting market, this may not be the right thing to do,” he said.

Therefore, it’s vital that you find the root cause of the lighting system problem promptly while not assuming it is the lamp that caused the failure.

When troubleshooting the lighting outage, use a multimeter to analyze the system. “Check first for the presence of a ground at the lamp assembly, then look for the voltage at the lamp connection. The last step is to check the lamp assembly,” he explained.

You then should be able to isolate whether you have a ground, power or a filament issue.
“This simple troubleshooting process could decrease your customer’s lighting cost by as much as 40%, if he has a typical application,” Van Riper added.

Because keeping costs down for your customer should be one of your top priorities, you want to make sure that you service his vehicle right the first time he brings it in to your shop.

If your customer brings his vehicle in for what he believes is a lamp failure, there are a few things you can look for to determine if, in fact, the lamp is at fault, and the problem is not with the connections.

According to Grote Industries, you should inspect be sure to inspect all lamps on the heavy-duty vehicle for the following signs of failure.

• A lamp with stretched or broken filaments typically has been subjected to heavy vibration.
• A yellowish, bluish or white haze on the inside of the lamp indicates that the lamp’s glass envelope has developed a leak.
• A dark, metallic finish on the inside of the lamp indicates an old age failure.
• Black, sooty deposits on the inside indicate a voltage surge that has burned out the filament.

  Once you’ve determined that the lamp is not the component that failed, you then can continue investigating the problem. If you’re aware of common lighting system failures, it will be easier to prevent those problems from recurring and causing even further damage to your customer’s vehicle.

• Corrosion is a major contributor to lighting system failure. As with most other components on the vehicle, corrosion in the lighting system can be caused by dirt, debris or water. To protect against corrosion, all the electrical wiring connections should be sealed against moisture with a non-conductive grease.

  Mark Assenmacher, director of marketing, Peterson Manufacturing Co., explained that it’s vital that the connections are not subjected to a harsh environment, and that it’s up to the lighting manufacturer, the driver and the technician to make sure they help protect all the connections.

• Shock, vibration and burnout can occur when the vehicle experiences constant road pounding when traveling down the highway. This causes the filaments in the bulb to break prematurely.

  According to Van Riper, shock can be caused by factors other than vibration, such as loading a container chassis on to a truck chassis, dump truck loading or tailgate banging, loose mounting of cargo hardware, unloading operations and impact with stationary objects such as poles or loading docks.

  To protect against vibration, install a lamp designed with shock-mounted mechanisms to cradle the bulb and absorb the effects of shock and vibration.

  Advanced technology can assist you in preventing the damage caused by vibration. Baseless bulbs are available which are suspended and able to endure heavy-duty applications much more than the traditional S-8 non-shock-mounted bulb units or the standard J-slot bulb socket.

  Technology also has introduced light-emitting diodes (LEDs), rated at 100,000 hours of operation. You may want to suggest your customer consider switching his lighting to LEDs because they are solid state and are much less susceptible to shock and vibration. Also, the electronics are sealed in epoxy, Van Riper explained.

• Inadequate wiring and cable can cause further damage. Cutting and splicing, or the merging of varying harnesses and wiring systems that are not designed to work together may break the system’s modularity, according to Grote.

  Suitable wiring can have a positive effect on product life and can reduce costs. The size of the wire or gauge is important as the use of a wire gauged too small can lead to dim or intermittent operation, excessive voltage drop and a possible fire hazard. A larger gauge wire than required can be used in any circuit for minimal additional cost, and it will offer reliable results, Van Riper said.

  The quality of the wire is very important. Stranded copper wire has a higher current-carrying capacity than aluminum wire of the same size, and it’s more flexible and less likely to break. Copper wire also resists heat better than aluminum wire in the case of short circuits, reducing the possibility of fire.

• Excessive voltage presents a problem for the bulb’s life. Failures caused by voltage occur as a result of load dumps, such as starting the engine with the lights on. Other sources of excessive voltage include heavy draw electrical devices such as lift gates or welders, according to Van Riper.

  Tell your customer to avoid starting his vehicle or using heavy draw accessories when the lights are on. Make sure to check voltage regularly to ensure the vehicle is operating within a safe range. Only one volt beyond the designed voltage will reduce the expected life of a bulb filament by more than 50%.

• Poor grounding can damage your customer’s lighting system. Therefore, installing a lighting product and harness system that uses an internal ground will help assure an absolute ground forever because it does not depend solely on the chassis ground, Van Riper said.

  This internal ground also helps eliminate rust and corrosion associated with chassis grounds.

• Loss of bulb contact may occur in your customer’s vehicle. In the traditional S-8 non-shock-mounted bulb units and the standard J-slot bulb socket, this is caused by corrosion or loss of spring tension.

  However, with the inception of the sealed baseless bulb lamp and soldered connections, product life is further enhanced, he added.

  Moving to LED technology also will prevent loss of bulb contact as it has no bulbs, no filaments, no internal wiring connections, and is completely sealed.

• Physical damage to the components of the lighting system occurs when there is no lamp protection in an open area, or when there is heat generation with no way to dissipate the heat.

  In order to prevent physical damage from ruining your customer’s lighting system, ensure that the housing or lenses are made of quality high-impact plastic.

  According to Van Riper, both lenses and lamp housings should be manufactured from a space-age plastic. Using recessed mounts and branch deflector designs further protect lamps from impact damage.

  He said that the best remedy for lighting system failures starts with a sound design from an experienced lighting manufacturer, followed by proper installation and application engineering from an OEM or installer. “With a good start, it is possible to achieve a ‘fit and forget’ lighting system,” he added.