Q Three weeks ago, we were southbound on the freeway in my one-owner 1999 Honda Accord V6 with only 71,000 miles on it. Then we heard a little noise, and the car immediately began a sharp 90-degree left turn into traffic with no steering input from me.

I could sense right away that this wasn't going to end well as a cement truck following us T-boned us and spun us across the highway into the concrete median barrier. We came to rest in the left lane pointing northeast. No one else hit us. No rollover. No air bags deployed because both impacts were sideways. We suffered no whiplash, but did get some bruises.

When the tow truck came, the driver was able to start the car and drive it up the ramp onto the truck bed -- he could steer the car! The insurance company declared the car a total loss. What could have failed in the steering system to cause this accident and yet be intermittent enough to permit at least limited steering onto the tow truck?

A Without a formal vehicle autopsy -- a complete mechanical and electronic inspection of the vehicle -- there's no way to know for certain. The most likely cause for a sudden "pull" or steering movement is a catastrophic tire failure. The sudden loss of pressure and destruction of the tire creates significant drag, causing the vehicle to turn sharply in the direction of the deflated tire. Whether the left front tire -- if it is flat -- failed suddenly while driving or was damaged by impact can often be determined by a careful visual inspection.

Do you recall whether the steering wheel spun suddenly to the left? If the vehicle veered left but the steering wheel stayed relatively straight, a broken steering component, tie-rod or suspension may have occurred. If one of these components is broken but also significantly bent, the damage likely happened on impact with the cement truck or barrier. If it is unbent and undamaged except for a break, it may have failed, leading to the incident.

Do you recall whether both front wheels moved with the steering as the driver drove the vehicle onto the tow truck ramp? If so, the steering linkage is probably intact and the spool valve -- which controls the "power assist" -- and the rack-and-pinion steering assembly are suspect.

If your vehicle is equipped with antilock brakes or traction control, have the powertrain control module (PCM) scanned for any fault codes associated with these systems. An unintended application of the left front brake could cause a sudden pull to the left.

Q The odometer on my 2000 Buick Century has gone dark and is unreadable. All the other instrument displays are properly illuminated. I noticed this shortly after having new tires installed. Any connection?

A I don't see any. If the tiny lamp that illuminates the odometer has failed but the odometer still works, it's a fairly simple task to replace the lamp by removing the instrument panel to gain access. If the odometer has failed but the speedometer still registers properly, the instrument cluster may be at fault. A scan tool can check for fault codes.

Q The turn-signal lights on my daughter's '91 Cavalier do not work occasionally, but the four-way flashers work fine. When you use the signal for a right or left turn, the dash light goes on, but the turn signals on the outside of the car do not blink. The next time you go to use them, they'll work. Any ideas would be greatly appreciated.

A This points to high electrical resistance somewhere in the circuit, the turn signal switch itself or a failing turn-signal flasher unit, which is under the dash on the right side of the steering column.