Charles C. Roberts, jr.

Snowplows and other snow removal related equipment are often installed as after-market additions to vehicles such as light trucks and some sports utility vehicles. Figure 1 is a typical conceptual drawing of how most of the snowplow kits are put together. The snowplow is mounted at the front frame area and houses a hydraulic motor and system to raise, lower and adjust the plow angle. Power wiring for the hydraulic motor and other accessories, like a salt spreader, are controlled via a relay system that is connected to the hand control in the vehicle cab. The hand control is connected to the hydraulic motor control and salt spreader control systems, using typical light gauge service wiring.

Figure 1

Installers of this equipment range from the professional to the "first timers." Professional installations usually work out well, while those installed by "part-timers" can be deficient. One of the most common problems with after-market snowplow installations is routing of electrical cables. After the apparatus has been mounted to the vehicle frame, little attention is paid to proper location and attachment of snowplow system related electrical wiring. Typical installation errors include: improper securing of the wiring, resulting in chaffing; wires contacting hot or rotating surfaces; and wires wound across sharp metal structures that penetrate the insulation and cause short circuits.

Figure 2

Figure 2 is a view of a vehicle that sustained a fire in the engine compartment near battery wiring. Figure 3 is a view of the salt spreader wire that had been routed through the frame area to the back of the vehicle. The wire was loose in the vicinity of the exhaust pipe and was periodically in contact with the exhaust pipe. This resulted in an electrical short circuit that overloaded the battery and caused an engine compartment fire.

Figure 3

Figure 4

Figure 4 is a typical after-market snowplow assembly that is mounted to the vehicle frame. A common mistake by installers is to pass electrical wires through holes in the vehicle frame without adding chafing protection such as using a rubber grommet. Figure 5 shows such an installation through a hole in the front body work of the vehicle. The arrow points to electrical arc eroded metal where a cut in the wire

Figure 5

Figure 6

insulation most likely occurred. Figure 6 shows an arc bead of copper in the area of the wire that shorted. The arc bead forms at high temperatures generated during the electrical fault, which in this case caused an engine compartment fire in the vehicle. Figure 7 is a view of a loose electrical power cable that was not properly secured to a cable clamp. It shorted as a result of chaffing and was welded to the wheel well as shown in the close-up of Figure 8. The heat from the short circuit caused a fire in the engine compartment and total loss of the vehicle.


Figure 8

When investigating the cause of a fire in a snowplow equipped vehicle, an inspection of the snowplow installation may yield evidence as to cause. Since these devices may be installed by unknowledgeable installers, they are prone to failures resulting from poor workmanship.