Q: We have a 2003 Ford Excursion 7.3 diesel that we love except for one thing. Sometimes when you start the car, the radio dash lights do not come on, which means the radio isn’t working along with that no air conditioning, no power windows and no garage door opener. Then everything magically starts working again some minutes later. Any ideas what might be causing this?

A: The most likely culprit is a worn ignition switch. When you turn the key to the “on” position, the switch may not be fully closing the contacts or the lock cylinder may not be rotating the switch far enough to electrically connect the power accessories you’ve listed. Have you tried wiggling the key in the “on” position once the truck has been started? Fortunately, the switch itself can be electrically tested to confirm whether it’s the problem. 

Q: Three dash warning lights stay lit while I’m driving my 2002 Buick Regal. When the car is first started, the “TRAC off,” “service engine soon” and “anti-lock” warning lights go out after the initial startup test like they are supposed to, but as soon as I shift out of park, all three warning lights come on and stay on until I turn the car off. And, no, I haven’t had the codes read yet. Any ideas?

A: Scanning the computer for DTC fault codes is the first step. Without specific codes pointing to the precise source of the problem or problems, all I can tell you is that both the traction control and ABS are disabled.

Paul Brand, author of “How to Repair Your Car,” is an ex-race-car driver. Email questions to paulbrand@startribune.com