Q: I have a 1996 Mercury Grand Marquis and the turn signals won’t work. The fuses are good and I have replaced the multifunction switch. I have checked the wiring and it appears to be good. Do you have any ideas? – G.C., Calumet City

A: If you’re sure that the fuses, wiring and multifunction switch are good, the only thing left in the circuit, besides the bulbs, is the lighting control module. And since I doubt that all the bulbs are bad, it’s more likely that the LCM is the culprit.

Q: I bought a used 2003 Cadillac DeVille. I had the oil changed right away, as I wasn’t sure how long ago the car had its last oil change. Within 2,000 miles, the oil level light came on and the engine was three quarts low on oil. It wasn’t leaking any oil and I don’t think it’s burning the oil. I changed to synthetic oil thinking this may help. Still, within about 2,000 miles the oil level light came back on. This time I had to add two quarts of oil. I also added a pint of STP, which was recommended by a mechanic. What could be my problem? Where’s the oil going? I hear that the Northstar engine is a very good engine. What do you think? – V.C., Crown Point, Ind.

A: You say you bought a used car and didn’t know when its last oil change was. Did you ask to see the vehicle’s maintenance record? It’s possible that this vehicle was neglected during its first life. Now you’re faced with the case of the “disappearing oil.” The oil has to be going somewhere. If you’re sure that there are no leaks, then the engine has to be burning the oil. Usually when an engine burns oil you see blue smoke out the tailpipe. But some of today’s exhaust systems are pretty good at hiding this oil from view. The Northstar engine is good, but it’s also known for some lower end oil leak issues. And like any engine, routine maintenance is important. I’d recommend taking your car to your local Cadillac dealer for a thorough inspection to see if it might be leaking some oil.

Q: I have a 1998 Mitsubishi 3000 GT. The brake light stays on all the time, even when the hand brake is off. Also, the headlights should shut off automatically when the ignition is turned off, however, they remain on. What’s wrong? – Aggie, e-mail

A: Regarding the brake light, the wiring diagram shows that it’s controlled by a switch on the parking brake and a fluid level switch in the master cylinder. The light could be on due to a low fluid level. If you’re sure that the fluid level is good and the parking brake is off, then either of those switches could be faulty or the circuit to those switches could be shorted to ground. As for the headlights, your Mitsubishi uses a device called a light automatic shut-off unit. This device could be faulty and needs to be tested. Ira Siegel is an automotive instructor and an automotive service excellencecertified master auto technician.

If you have auto-related questions for Siegel, you can leave queries at the Auto Adviser hotline, (708) 633-6839, or e-mail a question to autoadvisr@aol.com.