1. Verify that the joint shaft is not twisted or cracked.
2. Turn the joint shaft by hand and verify that the bearing rotates smoothly and freely.

Drive shaft
Joint shaft removal/installationMazda 6 Service Manual: Adaptive Front Lighting System (AFS) (Some models)
The adaptive front lighting system (AFS) automatically adjusts the headlight
beams to the left or right in conjunction with the operation of the steering wheel
after the headlights have been turned on and the vehicle speed is about 2 km/h (2
mph) or higher.
A system malfunction or operation c ...
Mazda 6 Service Manual: Rear door speaker inspection
1. Inspect for resistance between the rear door speaker terminals using an
ohmmeter.
If not as specified, replace the rear door speaker.
2. To verify that the rear door speaker outputs sound, apply voltage to the
rear door speaker and release using a 1.5-V battery.
If not outputs ...