When daytime running lights just won't run

Q The daytime running lights (DRLs) on my 2003 Chevrolet Suburban don't switch on during daylight. The truck has automatic headlights. I checked the DRL fuse, which looked good, but I replaced it anyway. No success. Then I replaced the DRL relay. Again, no success. Any ideas?

A The automatic headlight system in your truck will operate the DRLs when the key is in "run," the transmission in any position but park, the headlight switch in the "auto" position and the ambient light sensor indicates daytime conditions. Two suspects in your mystery are the DRL diode assembly and the DRL control module, both located to the right of the steering column under the dash.

Q I have a 2001 Tahoe with 96,000 miles. While I was on vacation, the vehicle sat in the garage for five days. When we went to start it, the battery was dead. I cleaned the terminals, which looked clean anyway, and it jump-started just fine. I took it for an hour's drive on the freeway to charge the battery, which is only 1 1/2 years old. The next day, my mechanic did a full charging-system diagnostic test but found nothing wrong, and the past few weeks the truck has been fine driving to and from work and weekends to a cabin.

The only anomaly is the fuel gauge. When sitting for several minutes at a stoplight, the gauge sometimes drops to zero, and the empty fuel tank warning light comes on, although it immediately resets when I start to accelerate.

I think it healed itself, meaning the problem went away without doing anything.

A A self-healing vehicle? Not likely. However, I have seen this occur. Years ago I had an older BMW sedan whose trip odometer stopped working in cold weather, then resumed proper function when the weather turned warm.

I suspect there's a connection problem in the sending unit, which is part of the fuel pump assembly inside the gas tank.

Q I have a 2001 Nissan Altima. The driver-side rear sway bar link broke several years back and was replaced at a Nissan dealer for $130. Now its passenger side rear sway bar link has broken, and I have the same exact symptom -- a loud, clicky sound when I make a turn. Is this something I can fix myself, or do I have to go to a dealer?

A The rear stabilizer, or sway bar, in your Altima appears to be a conventional design with a vertical link at each end connecting the bar to the suspension. Look under the rear, identify the broken link and decide whether you're capable of removing the rusty bolts that hold the link in place. If so, buy the new link -- check with parts stores to see if there's a universal or aftermarket link kit available. Jack up the back end, support it safely with jack stands and fix it yourself.