Owners of 2002-2003 four-wheel-drive (4WD) Chevy Trail Blazer, GMC Envoy and Olds Bravada SUVs may complain of a high-pitched squeal, squeak or whistle from the front axle area, particularly when the outside temperature is below 40 F.
According to GM, the most probable cause of the noise is a dry seal at the outboard end of the right axle intermediate shaft housing and/or the left side of the differential carrier. Newly designed seals with better lubricity (part #12479302 for the intermediate shaft; part #12471618 for the differential carrier) are now available to alleviate the concern.
To help differentiate between a wheel bearing problem and the seal issue, have a helper get in the truck, then raise the vehicle on a lift. With the 4WD system engaged and the transmission in gear, spray one seal then the other with water or silicone spray. If the noise diminishes, replace the offending seal(s), as required.
Some 2000-02 V8 Toyota Tundra pickup trucks built before VIN 5TBBT44142S304208, as well as 2001-02 Sequoias built before VIN 5TDZT34A42S110570, may turn on the check engine light and log trouble code P0135 and/or P0155 in computer memory.
The genesis of the problem, according to Toyota, lies in the inability of the existing upstream oxygen sensors to warm up within the prescribed time limits of the computer software. New oxygen sensors are now available to eliminate the problem. Order part #89465-34150 for bank 1 of the engine; part #89465-34140 for the sensor on bank 2.
Drivers of 2003 Town & Country, Caravan or Voyager minivans with V6 engines and 41TE automatics may complain of delayed or temporary loss of transmission engagement following startup.
The condition usually surfaces following an extended period of inactivity (four hours or more), and may be accompanied by a harsh 4-3 downshift and trouble code P0944 and/or P1791 in computer memory. According to DaimlerChrysler, problems in the front transmission pump are the most likely source of the trouble.
To make a definitive diagnosis, hook up your scan tool and record any trouble codes that might be present in computer memory. If codes other than those mentioned are logged, take care of them first. If all you see or are left with is the P0944 and/or P1791, replace the front pump with a revised, improved unit, part #05127197AA.
Once the pump swap is complete, make sure that the transmission control module is operating at the most up-to-date software level. If it isn't, have the module reprogrammed at a dealer.
“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]