Car won’t start, what’s wrong?

Dear Mike: My car won’t start. I can’t figure out why. I think it has spark. The fuel pump is making its customary whirring noise when I turn the key. I pulled out the spark plugs, but they don’t look wet or even smell of gasoline.

Is there some way to check to see if the fuel-injection brain is working without buying an expensive scan tool?

— M.S., New York, N.Y.

A: A quick check to see if the injection system is working at all can be done with a simple device called a “noid light.” It’s a small incandescent bulb in a socket with pins that plug directly into the wiring harness leading to your fuel injectors. You can buy a set to fit any number of applications for as little as $15.

Pop the connector off the injector and plug the noid light in. Crank the engine over. If the noid light flashes, the computer is operational enough to send voltage to the injector. If not, you’ll need to continue your detective work.

Consider this a quick-and-dirty test only — there are plenty of things that could go wrong to prevent the engine from starting. You could also do this test with a voltmeter, but it’s a lot easier to see the noid light flashing than it is to read the voltmeter scale.

Dear Mike: Our 2005 Nissan Altima has a more than noticeable leak after being driven for a while. I put the car on jackstands and found that the clear fluid collects on the passenger side near the firewall. The dealership says it’s water from the air-conditioning system. That was my original guess, but it’s never leaked like this before. It even leaks when we don’t use the a/c.

What is this fluid?

— B.R., Santa Monica, Calif.

A: Condensate water from the a/c evaporator under the dash is normally routed out of the car in the location you describe, so I’m sure this is what you’re seeing. Why does this happen when the a/c isn’t turned on? Your Altima, like most cars, runs the a/c compressor much of the time — even when you don’t think it’s on.

Any of the settings on the HVAC controller that signify that the windshield demisting is operating will run the a/c to dehumidify the air. That includes during cooler weather when you may, in fact, have the heat turned on. Relax. The leaking is normal.

Dear Mike: There is some gray plastic trim on the side of my car and it has become badly faded. The discoloration is very noticeable. I’ve tried wax and Armor All, but nothing seems to brighten the color.

Is there any product that will perk it up, or do I have to remove the trim and paint it?

— H.T., Battle Creek, Mich.

A: There are a couple of products I’m aware of that restore black trim — but not gray. Either the painted surface of the trim is, as you surmise, faded by the sun, or the paint film has worn through and what you see is the underlying plastic.

Bottom line: You’ll have to paint the trim to achieve a consistent color. The good news is that you can use a rattle can to do this, and if you mask carefully, you don’t need to remove the trim from the vehicle.

Be sure to choose an automotive paint for plastics, not something intended for rusty lawn furniture. And before painting, you’ll need to remove the Armor All or the paint will drip off the surface before it dries.

Thoroughly decontaminate the surface with prep solvent or lacquer thinner; if you use lacquer thinner, first check it on a small area, lest it dissolve the paint or trim. It shouldn’t, if all the surfaces are still in their factory state. If they’ve been repainted, the new paint may be less durable than the original.