Owners of 2008 F-Super Duty pickups, Ford Escapes and Mercury Mariners may complain that their blower motor doesn't work or shifts between high and low speed on its own when it does. The blower operation often returns to normal operation after cycling the ignition key.
According to Ford, the problem only afflicts trucks with automatic temperature control systems, is limited to vehicles built before Dec. 14, 2007 (F-Super Duty), or Dec. 17, 2007 (Escapes and Mariners), and is due to a defective blower motor controller. Installing an upgraded controller, part no. 7C3Z-19E624-C, should restore proper blower operation.
Some 2004-07 Chevy Aveo models with 1.6L engines may produce an intermittent misfire that develops during deceleration or steady-throttle driving. According to GM, the misfire typically occurs after a long period of inactivity (usually overnight), and may be accompanied by an illuminated Check Engine lamp with trouble codes P0300, P0700, P1781 and/or P0401 stored in PCM memory. Poor valve sealing is the most likely cause for the condition.
The solution depends on when the vehicle was built. On cars with a VIN breakpoint before 5B406012, replace the intake valves, exhaust valves and the valve stem seals with new-design components (part no. 96440081, 96830500 and 96840122, respectively). On cars built after and including VIN breakpoint 5B406012, just replace the exhaust valves and valve stem seals.
Some 2008 Corolla and Matrix models with 1ZZ-FE engines may flash the ABS and/or cruise light while being driven. In many cases, the air conditioning system may become inoperative when the warning lights illuminate. According to Toyota, all these seemingly unrelated problems are the result of a software glitch in the PCM. Installing a new module and having it programmed with the latest software should put an end to the trouble. To determine what PCM to install, just look at the part number on the old unit and reorder it. Check with a dealer for the specifics of the reprogramming job.
“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].