Q: I own a 2005 Buick LeSabre. The speedometer all of the sudden shows around 70 mph when I’m only going around 30 mph. I also noticed that my mileage on the odometer is increasing by about two times the actual miles I’m driving. Do you know what could be wrong? – L.O., Chicago

A: A speedometer and odometer that indicate a reading much higher than normal could occur if you installed much smaller (than normal) tires. But since you did not mention replacing the tires, it does not seem to be the case for your situation. I looked at the service information for your Buick and there’s a test procedure that a technician can follow for a speedometer and/or odometer that is inaccurate. One of the things that should be done is to install a scan tool and read the vehicle speed on the scan tool and compare it to the speedometer. If the powertrain control module is seeing the correct reading, but the instrument panel is displaying an inaccurate value, there could be something wrong with the circuit between the PCM and the instrument panel. This circuit is a data bus circuit, which means that many pieces of information are shared on this circuit and with many other modules. There could be a problem with this circuit or with one of the modules (like the instrument panel module) on this circuit. Take your Buick to the dealer or a repair shop that specializes in electrical repairs and they should be able to get to the source of the trouble.

Q: My 2008 Lexus RX 350 seems to have a jerking problem. I have brought it back to the dealer a couple of times and was told nothing is wrong. What do you think could be causing this? – Denise, Joliet

A: If it’s jerking when you’re driving, it could be a transmission problem. If that’s the case, take it to a transmission shop for another opinion. If it’s jerking when applying the brakes, it could be that the brake rotors are warped and have too much lateral run-out. Repair shops that specialize in brake repair should be able to solve your problem if the jerking is felt while braking. I did look to see if there were any service bulletins for your vehicle regarding this concern and found none. Take your Lexus in for another opinion or call Lexus at (800) 255-3987 to find a solution to your woes.

Q: I own a 2008 Pontiac G6. It recently started making a whistling noise that’s coming from under the dash on the right side of the vehicle. It didn’t make this noise before and only started doing this when the weather got cold. Do you know what it could be? – D.V., Orland Park

A: If your G6 has automatic climate control, it could be due to a faulty blower motor control processor. Service bulletin No. 09-01-39-003 suggests that you confirm the source of the noise by turning off the climate control system. If the noise goes away when you turn the climate control system off, the blower motor control processor will need to be replaced with a new unit.

Questions for Ira Siegel? Call the Auto Advisor Hotline at (708) 633-6839 or e-mail autoadvisr@aol. com. Siegel is an automotive instructor and an automotive service excellence certified master auto technician.