Q: I read your column every Sunday in the Boston Globe and find it very interesting and educational. My question involves why an intermittent shorted out speaker in the right rear door of my 1993 Lexus would continually drain the battery overnight when both the ignition key and radio were always turned off. I presume the speaker was shorted out because I could hear it buzzing sometimes and when I removed it everything worked fine. The dealer and others were no help but maybe you could clarify the electrical grounding problem for me.

A: If the speaker were shorted, it would make no noise at all, not a buzzing noise. Shorts usually don’t make noise, they blow fuses.

Something is draining current from the battery when the car is parked. This is usually easy to determine—all you need to do is get a meter to measure the current flowing from the battery. Normally, it would be 20-30 ma, enough to keep the radio presets, clock and engine computer memory alive. If it’s substantially more, something is still turned on. Just remove fuses from the fusebox one at a time, until it stops. Then you can disconnect devices from that circuit one at a time until you figure out what’s still on. More than once I’ve had to climb into the trunk and have someone slam the lid shut to see if a trunk convenience light was really going off, just like the light in the refrigerator. 

Q: I have a question about front end camber adjustment on my 1990 Nissan 2WD truck. How do I re-adjust a positive camber back to neutral (it's looking vertical inward at bottom). The truck has visible tire wear on outside. There aren't any shims to remove and it's already up as far except for washers. I'm worried that I may lose vertical ride height or cause a stiff ride if I let out torsion bar. The wheel assembly is not racking or loose on ball joints.  There's no asymmetric upper A-arm bolts (only 2005 after) to adjust. I'm scared to take it in after receiving 3 different opinions by repair places including placing shims front or back to bring up to neutral again.

A: I'm assuming the ride height is symmetrical and correct, and the caster is properly adjusted. If you can't remove any more shims from the upper control arm pivot, my guess is a bent spindle, from whacking a pothole or curb. You could remove the front discs and compare the angle of the spindle to a new one.

Q: In your May 2008 issue someone had asked whether his GPS or his vehicles speedometer was correct. I too have noticed that the speedometer reading vs. my GPS was different. I have a 2007 Kia Spectra, it seemed that the speedometer was 2 to 3 mph faster than the reading from the GPS. I knew that the GPS had to be more accurate and then wondered if the odometer could be doing the same thing. So I reset the trip meter on the car as well as the GPS, and found after traveling 100 miles or so that the odometer from both the GPS and car read the same. I'm no auto mechanic, but this would tell me that the sensors used for the speedometer and the odometer are separate, could this be true with all newer vehicles?, or perhaps this is just something found on a Kia. 

A: No, they use the same sensor. So the speedometer is just off calibration. Many are.

Q: Back in February you responded to a reader about little or no heat from his small engine, You stated that the water pump was probably not circulating enough water at idle to push/maintain the heat. I have the same issue with my 6 cyl. Dakota. Out on the highway, I have to turn the heat down or open a window, but around town, the snow on my shoes won't melt, no matter how long I'm driving around. I have checked for vacuum leaks, changed the anti-freeze and thermostat, etc. I have had the dealer and a friend who is a mechanic (full time) look at this  and no one has solved the problem, or come up up with  a good reason for it. Thank you. You are the first person to come up with a very logical reason. Now, what do you propose as the solution? I have tried to locate higher temperature thermostats, seems they quit doing that some time ago.  I can't put cardboard in front of the radiator, as I do go out on the highway often, and would not remember to remove it before starting. Do you know of anyone making larger after-market water pumps?

A: This was on the first page of google hits for “car electric booster water pump”. I’m sure there are others.