Did Radio Kill the Cruise Control?

Dear Car Talk

Dear Car Talk | Sep 09, 2014

Dear Tom and Ray:

Did I kill our cruise control by listening to baseball? Driving in the mountains, we listen to the San Francisco Giants' home station on the car radio. In our 1993 stick-shift Honda Accord with 203,000 miles, the game reception is bad in the mountains. But I realized that if I put a foot on the brake pedal just slightly, the reception clears up! Touching the brake pedal also turns on the brake lights and disconnects the cruise control (if it's on). Now the cruise control has died. (1) Was it old age, or did my riding the brakes just slightly kill it? (2) What can we do under the hood to improve reception so we don't miss the games? (3) How does triggering the brake lights (or hitting the cruise-control switch) improve reception?

-- Connie

RAY: Great questions, Connie. You would think that two guys who have been on the radio for 30-odd years would have a clue how it works.

TOM: But you'd be wrong.

RAY: Generally speaking, AM radio reception often is disturbed by a type of interference called RFI -- radio frequency interference. And yes, we're sure the "F" stands for "frequency," despite your frustration with it creating static during a key at-bat in the bottom of the ninth inning.

TOM: RFI in a car can be constant, intermittent or related to the engine speed. Depending on which type it is, different components can be suspect.

RAY: For instance, if the noise changes with the speed of the engine, it could be the ignition, a fuel injector or the alternator. If it's constant, it could be something like the fuel pump, or a fan motor if you leave it at the same speed all the time.

TOM: Who knows why your problem goes away when the brake lights are engaged? Maybe something is getting grounded by that connection, or an additional wire gets incorporated somehow as part of the antenna.

RAY: But in our experience, these problems are very, very difficult to eliminate. So I'm going to suggest that you circumvent the problem entirely. How? Get satellite radio.

TOM: You'll get every ballgame, everywhere in the country, and your reception, particularly in the mountains, should be perfect all the time.

RAY: Satellite radio has more trouble in dense, urban areas with tall buildings. But on a mountain, you'd have a clear shot right to the satellite.

TOM: In terms of your cruise control, the first thing to check is the fuse. That would be the simplest and cheapest thing to fix.

RAY: If the fuse is fine, then the switch at the brake pedal could be worn out, or out of adjustment. A bad switch (stuck permanently in the "open" position) would prevent you from engaging the cruise control.

TOM: Did it have anything to do with you riding the brake pedal while listening to ballgames? It could have. But it also could have something to do with the 203,000 miles you've got on the car.

RAY: In any case, your mechanic can test that switch for you, and replace it if necessary. And that should get you through at least the next few seasons, Connie. Good luck.

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