Chrysler says that the rear defroster switch on some 2010 Chrysler 300s, Dodge Chargers and Jeep Grand Cherokees and Commanders with automatic temperature control (ATC) systems may be difficult to engage when pressed or may disengage once locked in place. According to the carmaker, the problem typically occurs on vehicles built before Sept. 19, 2009, and is due to too much deflection in the ATC control head. Stiffening up the control head should eliminate the trouble.
The illustration above shows the back side of the ATC control head after removal from the vehicle. Look closely and you'll see two indentations with holes, as indicated by the arrows. Installing two specially made screws, part No. 68078941AA, into these holes will stiffen the control head sufficiently to prevent the defroster switch from sticking against the sides of the bezel. After the modification is completed, just reconnect the wiring, reinstall the control head and confirm that the switch works properly.
Some 2006 Chevy Cobalts and HHRs with 2.2-liter four cylinder engines (VINs D and F) may turn on the Check Engine light and log one or more of the following trouble codes in computer memory: P0128, P0326, P0420, P0604, P0717 and P2431.
GM says it's unlikely that any drivability symptoms will be present when the Check Engine light illuminates, and it attributes the condition to software issues in the PCM. Flashing the module with updated calibration files is the only remedy. Check with a dealer for the application specifics of the reprogramming job.
Some 2009 Ford Escapes and Mercury Mariners with 2.5-liter engines, six-speed automatic transmissions and build dates before March 5, 2009, may exhibit a rough idle when first started after a prolonged period of inactivity.
According to Ford, the idle trouble usually occurs with the transmission in Drive and the engine loaded (such as when the air conditioning is on), and is due to software anomalies in the PCM. Reprogramming the module with updated software is the only surefire remedy. Check with a dealer for the specifics of the flash.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected]