before you throw parts at this vehicle,read this first. Subject: Start Up Cooling Fan Noise - Updated EV Cooling Fan and PCM Calibration
Models: 2002-2003 Chevrolet TrailBlazer
2002-2003 GMC Envoy
2002-2003 Oldsmobile Bravada
with 4.2L Engine (VIN S - RPO LL8)
On rare occasions, a roar noise, lack of power, and/or delayed transmission shifts may be experienced on acceleration, shortly after cold starting the engine. Some customers may mistake this as a transmission slip concern. Upon inspection, no DTCs will be stored in the PCM. recalibrate the PCM with the latest TIS calibrations and replace the EV cooling fan clutch using the part number listed in the GMSPO parts catalog. At this time, all available PCM calibrations and EV cooling fan clutches may improve this concern on the models above. If this concern still exists after installing the updated EV fan clutch and PCM calibrations described above test drive the vehicle for at least 4 minutes with the engine RPM at 1,800 RPM or greater to determine if a P0495 sets. If no DTCs set, this is most likely a characteristic of the vehicle as described in Section 5 of the Owner's Manual.
Oct 21, 2008 at 8:44 PM
