Ford Faqs

Investigators installed damaged cruise control switches in Ford vehicles and then waited for them to cause a fire. The result was a phenomenon that has never seen before. Just two inches long, the Texas Instruments Model 9F924 speed control deactivation switch does not look like a device that could be deadly. But a sporadic malfunction in the switch that sparked engine fires stumped engineers at the National Highway Traffic Safety Administration for two years.

The $20 switch, which shuts off the cruise control when a driver taps the brakes, became the subject of one of the most exhaustive and complex investigations in the agency’s history. It created an expensive and embarrassing problem for the Ford Motor Company, which initially disputed suggestions that the switches were starting fires.

When the repairs are made to the last of 6.7 million potentially defective switches, the Ford recall may be the second largest in United States history. I’ve been through hundreds of investigations, and the complexities here were enormous, said Richard Boyd, chief of the medium and heavy-duty vehicle division in the safety administration’s office of defects investigation. Going in we had no idea. Was the switch causing the problem or was the vehicle?

The answer, spelled out in a government report issued this month, turns out to be both. After an investigation that involved collecting damaged cruise control switches from across the country, installing them in Ford vehicles and waiting for them to cause fires, the agency determined that a phenomenon never seen before was to blame. Unbeknown to anybody, Mr. Boyd said, you can actually create a small vacuum when you let off the brakes.

The force of that vacuum, investigators determined, was weakening a seal in the switches installed in millions of Ford pickup trucks and sport utility vehicles. With the plastic seal broken down, brake fluid was able to leak onto the electrical side of the switch and cause corrosion. Over time, that corrosion can build up, causing the switch to overheat and ignite an electrical fire. Government investigators began hearing complaints about the switches catching fire in 1999. That year, Ford recalled 279,000 cars from the 1992-93 model years: the Crown Victoria, Lincoln Town Car and Mercury Grand Marquis.

Then, the problem was thought to be a manufacturing defect, but the recent investigation suggests that the vacuum-weakened seal was the culprit. The number of complaints declined, and the agency considered the issue resolved. In 2002, there were reports of more Crown Victoria fires. But after monitoring the situation for two years, the agency decided the number was too low to warrant a recall.

Around the time the agency decided that a second Crown Victoria recall was not necessary, reports of fires in F-150 pickups began to trickle in. By June 2004, the agency had begun an inquiry into the truck fires. At first, investigators believed the switches were overheating because of a problem that originated in manufacturing the switch. The switch was in 16.5 million vehicles when the investigation began, but it appeared to overheat only in the 12.5 million that were wired so that the switch received power continuously, even when the ignition was off.

Perplexing investigators further was the fact that the switch was malfunctioning in some models but not in others. Explorers, for example, had a relatively low fire rate; fires were more common in Expeditions. The simplest solution would have been to tell Ford to recall all 12.5 million vehicles with switches that always had power. But the agency did not yet understand the cause of the problem, and it cannot order a recall without making a solid case.

The burden of proof in a defect investigation is on the government, Mr. Boyd said. So at the end of the day, if we went to Ford and said we want you to recall 12 million vehicles, Ford would say. Ford’s response to the fires, first refusing to acknowledge that the switches posed a fire hazard, then conducting four recalls over seven years angered fire victims and consumer advocates. It does not hurt their cases that Ford was accused of dragging its feet in other high-profile recalls.

Ford did not acknowledge that the switches were causing fires until last September, when it recalled 4.5 million vehicles from the 1994-2002 model years, including Ford Broncos and Expeditions and Lincoln Navigators. But Ford and the government still did not know why the fires were starting, despite exhaustive efforts to find the cause.

In a field in suburban Atlanta, with firefighters standing by, the traffic safety agency put faulty switches in four Ford vehicles and waited until they caught fire. Some of the defective switches were obtained by Bruce York, the chief investigator on the case, who went to dealerships and junkyards in the Washington area in search of used switches and samples of brake fluid.

Government engineers then studied the burn patterns. The agency eventually sent defective switches to the National Institute of Standards and Technology, a federal agency, which determined that the switches were failing because the seal separating the electric side from the side containing brake fluid was wearing down.

Why that was happening was still unclear, however. One possibility was a vacuum effect in the brake line, created when a driver releases the brake, that would cause the seal to invert and wear down over time. Engineers had never seen that happen in cars.

This summer, they began to focus their investigation on what role that vacuum might play. So they looked at data on brake-line vacuum that had been collected in an unrelated investigation. They found that with the right amount of vacuum the seal would invert, and they determined that the seal was especially vulnerable in vehicles with more vacuum in their brake lines.