Ford Motor Co. is expanding a 2005 safety recall covering speed control activation systems to include 1.2 million additional models.

Added to the list are gas and natural gas ’94-’02 F-250 through F-550 Super Duty trucks; ’00-’02 Excursions; ’94-’96 Econoline vans; ’96-’02 E-450 vans; and ’98 Explorers and Mountaineers.

The previous recall covered 5 million vehicles.

“Today’s action includes those vehicles that were identified as having an interaction issue between the speed control deactivation switch and the brake system that could, in rare cases, cause the switch to overheat and ultimately catch fire,” Ray Nevi, assistant director of Ford’s automotive safety office, says in a statement.

Dealers will install a fused harness for the switch that will cut off power should electrical current increase due to a leaking switch.

“After a year of intensive research, including working with (National Highway Traffic Safety Admin.) engineers, we have concluded that certain factors on the affected vehicles may lead to the switch overheating,” Nevi says, citing the specific orientation of the switch on the brake master cylinder and repeated high vacuum events that occur during normal braking.

In some instances, these vacuum events can cause failure of the speed control deactivation switch, potentially leading to corrosion and the leaking of brake fluid.

In rare occurances, the events could combine to result in engine fires, the auto maker says.

Ford says it has a sufficient number of fused wiring harnesses to correct the problem.