Q The cruise control on my 1990 Bronco II with 60,000 miles has stopped working, and it won't turn on. I have replaced the fuse, switches and servo assembly with good working used ones and checked the brake-light vacuum switch. Am I missing something?
A Check the electrical terminals on the connector for the servo. Any corrosion could prevent a solid contact between terminals and keep the system from working. Flushing with brake cleaner or an electronic contact cleaner, then adding a dab of silicone dielectric grease can help prevent moisture from invading the connection.
Even though you checked the brake-light vacuum switch, make sure the brake lights work properly, including all three brake lamps. Does the speedometer work properly? Check the speed sensor and its connections. Does the horn work? If not, check the horn relay. And finally, check all vacuum hoses and lines to make sure vacuum is available at the cruise servo.
Q I have a 1999 Plymouth Voyager with the 3.0-liter engine. When I recently had the rear brakes done, the mechanic noticed that the right front constant-velocity (CV) boot was torn. After they replaced the boot, I noticed a bad vibration in the front end between 55 and 65 miles per hour. I brought it back, and they told me that the front rotors were bad and replaced them. The problem persisted, so I had all four tires rebalanced. That still did not cure the problem. Any ideas?
A Unless they installed a split-type CV boot that does not require removal of the axle, the drive axle had to be unbolted and removed to install the new boot. Because dirt and debris can enter the CV joint while the boot was torn, it may have been more prudent to replace the entire axle assembly with a remanufactured unit. With that said, have them double-check the installation of the drive axle to make sure the CV joints and flanges are tight. Any play in the CV joint could be felt as a vibration like the one you describe. Warped brake rotors would not cause a vibration at this speed unless you applied the brakes.
Any time there's a vibration from the "driven" end of the vehicle, try shifting into neutral for a moment while experiencing the vibration. If the vibration changes or stops, it's related to the drivetrain. If not, it's more likely caused by tire, wheel or hub, or perhaps the axle. And finally, touch the brake pedal with your left foot just enough to activate the brake light switch while experiencing the vibration. If it stops and then comes back when you release the brakes, the torque converter clutch may be slipping.
Q I have a 2000 Lincoln LS V8 with a sealed transmission. It has 86,000 miles and the transmission works fine. One Ford dealer told me I should have the transmission flushed and the pan dropped [removing the pan that holds the transmission fluid] to replace the filter. Another Ford dealer said I should not flush the transmission but should have the pan dropped and filter replaced. He said flushing can harm the sealed transmission. Who is right?
A According to Ford, the transmission fluid should be inspected every 15,000 miles and replaced every 30,000 miles. The first scheduled replacement of the transmission fluid filter is 150,000 miles.
The transmission in your vehicle is not sealed; it just doesn't have a dipstick for you to check the fluid level. Checking the level and replacing the fluid are done through a special drain port in the bottom of the pan and requires special equipment. Flushing can't harm a transmission, but debris loosened and circulating after the flush certainly can. I'd suggest changing the fluid now, and every 30,000 miles in the future.