An auto-in-the-garage electrical fire

Aug 1, 2007 by

The case of the month concerns an auto/garage fire. The vehicle manufacturer issued a recall notice for an electrical problem. The insured took his nearly new vehicle to the dealer for he required work. He picked up his car about 5 pm, drove home without incident, and parked the car in the garage. About 2 am, he was awakened by smoke and flames. The fire department extinguished the fire and determined that the fire started in the garage. Each interested party brought in their own CFI, but they could not agree as to the origin of the fire. At that point GEI was brought in.

The vehicle sustained a burn to near completion. Most of the combustibles in the interior, exterior, and the engine compartment were consumed by the fire. Large aftermarket twenty-inch diameter wheels were found on the vehicle mounted with aftermarket wide tires, a navigation system and sound system.

A large amount of drywall and insulation material was found inside the vehicle. This was fire debris from the garage where the vehicle burned. The front of the vehicle had been cleared to accommodate the preliminary inspection. The front seats had moved to their full back position, most likely during the fire. The remains of magazines and clothes were found behind the right front passenger’s seat. A lightly burned umbrella was found hooked on wires beneath the driver’s seat.

With possible spoliation from the previous inspection combined with the vehicle being too badly burned led to the conclusion that it is not possible to determine with absolute certainty the cause and origin of the fire. However, the fire appeared to have started in the left front interior of the vehicle.

The engine compartment was heavily fire damaged. All of the rubber, plastic, and light aluminum components of the engine compartment were consumed. Our expert examined the fuel injection system, the power steering system, the air conditioning system, the automatic transmission system, and the engine compartment electrical system. The battery was consumed; the alternator was heavily fire damaged and seized. The engine compartment fuse box was consumed. No short-circuits or other pre-fire problems were found to the battery cables or the engine compartment wiring harness.

The recall was for a possible incorrectly routed electrical wiring loom, under the drivers seat. Some wiring harnesses lacked a particular plastic fastener that secured the wire loom from, over time, drooping down into the path of the frame of the seat, as it moved forward and backward due to the seat position requirements of different drivers. The concern was that over time, the wire insulation would be rubbed off, and eventually short-circuit. The manufacturer provided a replacement section of wiring that would be safely out of harms way, due to its special fasteners, when the seat was advanced and retracted.

The recall notice instructions to the dealer technicians were very explicit in warning where not to route the wires. In particular, it said, “CAUTION: Do NOT route the lumbar adjustment control harness between the seat lifter bar and the metal seat pan.”

Our expert carefully examined this area and found the wires to be precisely there. During the recall service, the wire loom was misrouted between the driver’s seat lifter bar and the metal seat pan. This action was specifically warned against in the service procedure to satisfy the recall. Additionally, the driver was a tall man and had moved the seat to the farthest back seat position. This pinched the wires, rubbing the insulation off as he drove home. Once the exposed wiring made contact with the seat tray, the wires short-circuited and generated sufficient heat to melt the wiring insulation and ignite the fire. The fire then progressed upward in the areas of available fuel. This was not a circuit that turned off with the engine-it was always “hot”. Hot enough to nearly burn down the house.

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