FCA L.L.C. reports that some 2008-09 Jeep Grand Cherokees with 6.1-liter engines and automatic transmissions may idle roughly on cold startup.
In many cases, the check engine light also will be illuminated, with trouble code P050D stored in computer memory. If normal troubleshooting fails to reveal the cause of the problems, a glitch in the PCM software is the likely culprit. Reprogramming the module with an updated calibration is the only reliable fix.
Check with a dealer for the application specifics of the software upgrade.
"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].