Editor's note: An earlier version of this story incorrectly described the amount of time needed by dealer technicians to test a software upgrade on the Jeep Cherokee's nine-speed automatic transmission. The optional test drive should take no more than 78 minutes.
DETROIT -- Chrysler Group continues to tweak the software that operates the complex nine-speed automatic transmissions it will use to power all of its front-wheel-drive-based vehicles.
A new software recalibration covers more than 100,000 Jeep Cherokees built before May 5 to address continuing issues with the way some of the nine-speeds shift gears.
Chrysler delayed the launch of the Cherokee for almost two months last year to tweak the transmission's software.
In addition to a five-minute software reset or "reflash," a May 15 technical service bulletin advises technicians in certain cases to perform an "adaptation drive learn" -- taking the Cherokee out for a test drive of up to 78 minutes to ensure that it is shifting correctly.
Like many electronic transmissions, the nine-speed learns the driving habits of its main driver and adapts the shift patterns accordingly.
Not all sold Cherokees require the reflash, according to the automaker, but it is available under warranty to customers who complain about the feel or operation of the transmission.