Q: My wife has a 2011 Dodge Grand Caravan with 76,000 miles. We are having an ongoing problem over the past two years with the vehicle not starting. Attempts have varied from one, two ir five attempts to 20-25 most recently. The dealer had advised my wife in the past to lift the hood and tap/hit the control panel. She did and it worked! We have asked if they would perform a diagnostic check (no), if there was a recall for this situation, to put in a new ignition (advised they would not replace if they were not sure that was the problem) and if they have heard of this before (no). What should I do?

A: In my opinion, you have two choices. First, insist that the dealer check Chrysler service bulletins for information covering this symptom. My ALLDATA database pulled up a series of reprogramming bulletins to address a number of driveability issues with this drivetrain. One in particular, TSB 18-006-11 REV A, dated February 2011, suggests reprogramming the PCM to address DTC fault code P0128 — long crank times due to predicted coolant temperatures at start-up differing from actual coolant temperature.

If for some reason the dealer is still unresponsive to your request, take the vehicle to an auto parts store that offers free DTC code reading, or better yet, find a more responsive dealer.

There certainly could be a number of other causes for long crank times, including a lack of fuel pressure or an ignition issue, but the first step is to interrogate the PCM for fault codes to pinpoint the cause.

Q: Thank you for addressing the issues on our Cadillac SRX. I just spoke with the tire shop where we bought the tires. They were not familiar with the phrase "run-out" or "road force balance." Can you help me with that? Also, I question whether the "rolling diameter" is the same on all four tires when the front and back are different-sized. Is that right?

– P235/65-17 front and P255/60-17 rear – both have the same rolling diameter of 29 inches and thus are appropriate for an AWD vehicle.

"Run-out" is the side-to-side movement of the tire sidewall and tread as it rolls. Like a warped brake rotor, the tire does not rotate in a perfect vertical plane. This is not a tire wear problem — it's more likely caused by an internal issue.

"Road force balance" is a tire balancing system that duplicates real-world driving. The tire/wheel is mounted on an arm/hub assembly that "loads" the tire as it spins against a rotating drum. Sensors accurately identify any significant "out-of-round," run-out and imbalance conditions and suggest corrective measures, including very accurate balance weight amounts and positions.

Q: I have a 2005 Dodge Caravan with a locking sliding door on each side. First the left door power locking device quit working and shortly after that the right sliding door quit. Is the problem in the door or elsewhere?

A: Try the KISS principle first. A scan tool may identify any power/ground issues with the door locks. Try disconnecting the battery for a few minutes, then reconnect it and try the locks. It might also be worth checking the electrical connectors that carry voltage to the locks. If these simple steps don't help — and they probably won't, since only the sliding door locks are the issue — the problem is more likely the power door lock actuator in each door. A quick Internet search found this to be a relatively common issue.

The fix is to remove the door panels and replace the actuators. With the panels off and the actuators unplugged, you can check whether voltage is reaching the actuator. New OEM actuators are $70/right side and $125/left side. Aftermarket actuators range from about $25 to $50.