1. Inspect the dust boot on the drive shaft for cracks, damage, leaking grease, and looseness in the boot band.

2. Inspect the drive shaft for bends, cracks, and wear in the joint or splines.
Joint shaft disassembly/assembly
Drive shaft removal/installationMazda 6 Service Manual: Direct Mode
Direct mode can be used for temporarily switching gears by operating the steering
shift switch while the vehicle is being driven with the selector lever in the D
range.
While in direct mode, the D and M indication illuminate and the gear position
in use is illuminated. Direct mode is canceled ...
Mazda 6 Service Manual: Variable air duct (vad) shutter valve inspection (l3)
1. Remove the air cleaner case. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION.)
2. Disconnect the vacuum hose from the VAD shutter valve actuator.
3. Connect a vacuum pump to the VAD shutter valve actuator.
4. Apply vacuum and verify that the rod moves.
If the rod dose not move, replace the a ...