Q: I have a ’98 Mercury Grand Marquis. The problem is that the battery light on the dash illuminates periodically. Sometimes it comes on and stays on for a while and other times it remains off. The charging system has been tested and found to be okay. The battery and drive belt have been replaced, but the problem remains. Ford has not been able to solve this problem. This has been going on for the past five years and seems to have initiated after driving through a heavy downpour of rain. I have spoken to others with Grand Marquis, Crown Victoria and Lincolns and they have experienced the same problem. I’d like to trade the car in but fear that I won’t get much for it with the light coming on and off. Can you help? -- R.C., Valparaiso, IN

A: R.C., the battery light in your Mercury Grand Marquis is controlled by a circuit inside the alternator. Even though the system appears to be charging, there could be something wrong with the alternator causing the light to illuminate intermittently. But before you go and have the alternator replaced, I would recommend that a technician thoroughly inspect the related wiring. Ford did have problems with moisture affecting electrical connections. A technical service bulletin (#98-24-6) was released and it mentions to use electrical grease (part # F8AZ-19G208-AA) to reduce moisture corrosion at terminals. Don’t replace the alternator until all the associated electrical connectors and circuits have been thoroughly inspected and eliminated as the potential culprit.

Q: My 2002 Mazda Protégé 5 didn’t pass the emissions test. My printout says that the oxygen sensor, catalyst, and EGR monitors were not set to “Ready”. The dealer said I need a new catalytic converter, but I’m not so sure. A friend connected a scan tool and found no codes. The “Check Engine” light isn’t on either. According to my friend who scanned my cars computer, the oxygen sensor’s voltage is fluctuating rapidly like it should and he doesn’t know why these monitors haven’t set. Can you help? -- P.H., Palos Hills

A: P.H., the vehicle may need to be driven under certain operating conditions. As is the case with 1996 and newer cars, the on-board diagnostic system automatically performs tests (known as monitors) while you drive. But before certain monitors are performed, certain driving conditions need to be met. Usually, it takes a mixture of short-trips and long-trips, and various vehicle speeds to get these monitors to set. However, some vehicles are more difficult at getting their monitors to set. Sometimes a manufacturer will need to update the engine computer with updated software. I looked to see if there were any service bulletins for updated software for your car, but found nothing. You’ll want to have your Mazda inspected by a technician who specializes in emission repairs. I suggest you visit the following website: http://www.epa.state.il.us/air/vim/pdf/rfpr-october-2007.pdf. It lists shops in the area, how effective they are at repairing emission problems, and whether the Illinois EPA has trained them.

AutoAdviser: Ira Siegel is an Automotive Instructor and ASE Certified Master Auto Technician. If you have auto-related questions for Ira Siegel you can call and leave your questions at the Auto Adviser Hotline at 708-633-6839 or e-mail a question to Autoadvisr@aol.com.